Untitled Flashcards Set

Year 8 Science: Digestion Checklist Concept Tick Objective: Explain that multicellular organisms contain systems of organs that carry out specialised functions that enable them to survive (and reproduce). Outline the role of the digestive system in the human body. The digestive system plays a crucial role in breaking down food and absorbing nutrients that the body needs to function. The digestive system helps the body get the nutrients it needs for energy, growth, and repair. List two other systems and explain how they assist with survival. The circulatory system is one of the other important systems in the body. It includes the heart, blood, and blood vessels. The main job of this system is to transport oxygen, nutrients, and hormones to different parts of the body and remove waste products like carbon dioxide. By doing this, the circulatory system helps the body stay balanced and ensures that every cell gets the oxygen and nutrients it needs to survive. Another important system is the respiratory system, which includes the lungs and airways. Its job is to bring oxygen into the body and remove carbon dioxide, a waste product that the body creates.This system is essential for survival because it provides oxygen to the body and gets rid of harmful waste. Objective: Explain that the digestive system is one of those body systems that enable survival, and define the purposes of ingestion, digestion and egestion. Explain how the digestive system assists with survival. The digestive system plays a vital role in keeping the body alive and healthy by breaking down food so the body can absorb the nutrients it needs for energy, growth, and repair. When we eat, the digestive system turns food into smaller molecules like sugars, proteins, and fats that our cells use. These nutrients are absorbed into the bloodstream, providing the body with the energy it needs to function. The digestive system also helps remove waste products that the body doesn't need. Without a properly working digestive system, the body wouldn't get the nutrients it needs, and harmful waste could build up, which would make survival impossible. Define ingestion, digestion and egestion. Ingestion is the process of taking in food and liquids through the mouth. This is the first step in the digestive process. Digestion is the breakdown of food into smaller molecules by both mechanical (chewing) and chemical (enzymes and acids) processes. This allows the body to absorb nutrients. Egestion is the process of eliminating undigested food and waste products from the body, mainly through the anus as faeces. It is the final step in the digestive process, where the body gets rid of things it cannot use. Objective: Compare and contrast, with specific examples, mechanical and chemical digestion. Define mechanical digestion. Provide an example. Mechanical digestion is the physical breakdown of food into smaller pieces without changing its chemical structure. An example of mechanical digestion is chewing. When we chew, our teeth crush and grind the food into smaller pieces, making it easier to swallow and further break down. Define chemical digestion. Provide an example. Chemical digestion is the process by which food is broken down into smaller molecules by the action of enzymes and acids. An example of chemical digestion occurs in the stomach, where stomach acids and enzymes break down proteins in the food we eat, turning them into smaller molecules that can be absorbed by the body. What is the difference between mechanical and chemical digestion? The main difference between mechanical and chemical digestion is that mechanical digestion involves physically breaking down food into smaller pieces (such as chewing), while chemical digestion involves breaking down food into simpler molecules using enzymes and acids. Mechanical digestion doesn't change the food's chemical structure, but chemical digestion does. What happens in the mouth during digestion? In the mouth, both mechanical and chemical digestion begin. The teeth break the food down into smaller pieces (mechanical digestion), while saliva, which contains the enzyme amylase, starts to break down starches into simpler sugars (chemical digestion). The food is then mixed with saliva to form a soft mass called bolus, which is ready to be swallowed. List the 4 different types of teeth. Incisors, canines, pre-molars, molars. Describe the role (function) of incisors. Incisors are the flat, sharp teeth at the front of the mouth. Their main role is to cut food into smaller pieces. They are ideal for biting into food, such as fruits and vegetables. Describe the role (function) of canines. Canines are the pointed teeth located next to the incisors. Their role is to tear food, especially meat. They are designed to grip and rip food apart, helping with the breakdown of tougher substances. Describe the role (function) of pre-molars. Pre-molars are flat-topped teeth located behind the canines. They are used to grind and crush food into smaller pieces, making it easier to swallow. Pre-molars are important for breaking down food before it moves on to the molars. Describe the role (function) of molars. Molars are the large, flat teeth at the back of the mouth. Their main function is to grind and crush food into even smaller pieces, which helps with the digestion process. They are particularly important for breaking down hard food like nuts and meat. Objective: Explain the importance of food as a source of energy, for providing building blocks for growth and repair, and chemicals for regulation and control. List the 5 key nutrients required in a diet. Carbohydrates, proteins, fats, vitamins and minerals. List three examples of vitamins, their role, and food sources. Vitamin A: Important for vision, immune system function, and skin health, found in carrots, sweet potatoes, spinach. Vitamin C: Helps with the growth and repair of tissues, boosts the immune system, and helps the body absorb iron, oranges, strawberries and capsicum. Vitamin D: Helps the body absorb calcium and maintain healthy bones and teeth, found in fatty fish, fortified dairy products. List three examples of minerals, their role, and food sources. Calcium: Essential for strong bones and teeth, muscle function, and nerve signaling, found in dairy products, leafy green vegetables. Iron: Helps form haemoglobin in red blood cells, which carries oxygen throughout the body, found in red meat, beans, fortified cereals. Potassium: Helps regulate fluid balance, nerve signals, and muscle contractions, found in bananas, potatoes, spinach. Why are probiotics important in maintaining a healthy gut microbiome? Probiotics are beneficial bacteria that help maintain a healthy balance in the gut microbiome. They support digestion by helping break down food, absorbing nutrients, and protecting against harmful bacteria. Probiotics can also improve immune function and prevent digestive problems like bloating and irritable bowel syndrome (IBS). A healthy gut microbiome is important for overall health, as it affects not only digestion but also immunity, mood, and even skin health. Objective: Describe the nature of carbohydrates, lipids (fats & oils), and proteins, including their basic chemical structure, roles they play in the body, and food sources. Outline the importance of carbohydrates in our diet. List 3 foods you will find carbohydrates in. Carbohydrates are a key source of energy for the body. When consumed, they are broken down into glucose, which is used by the cells for fuel, especially in the brain and muscles. Carbohydrates help maintain blood sugar levels and provide energy for daily activities, exercise, and bodily functions. Food sources: Bread, rice, pasta. Outline the importance of protein in our diet. List 3 foods you will find protein in. Protein is essential for the growth and repair of tissues, muscles, and cells. It also plays a key role in the production of enzymes, hormones, and antibodies that support immune function. Protein is especially important for building and repairing muscles after physical activity. Food sources: Chicken, eggs, beans. Outline the importance of lipids in our diet. List 3 foods you will find lipids in. Lipids (fats and oils) are important for energy storage, providing a long-term source of energy. They also help in the absorption of fat-soluble vitamins (A, D, E, and K), support cell structure, and maintain healthy skin and organs. Healthy fats, such as omega-3 fatty acids, are also important for heart health. Food sources: Avocados, olive oil, nuts. Draw and describe the chemical structure of a monosaccharide. Provide one example. Glucose Draw and describe the chemical structure of a disaccharide. Provide one example. Sucrose Draw and describe the chemical structure of a polysaccharide. Provide one example. Starch Fats and oils are known as lipids. The chemical structure of them are made up of carbon and hydrogen has three long tails and a short head. What is the key difference between a fats and oils? The key difference between fats and oils is their state at room temperature. Fats are typically solid at room temperature and are usually found in animal products like butter or lard. Oils are typically liquid at room temperature and are usually derived from plants, such as olive oil or vegetable oil. This difference arises due to the types of fatty acids they contain, with fats often having more saturated fatty acids, while oils contain more unsaturated fatty acids. Proteins are very large molecules chemically bonded together by building blocks called amino acids. Objective: Explain the roles of various enzymes and relate their function to the overall role of the digestive system. The enzyme amylase is found in saliva. What does amylase do during digestion? A diagram may help. Amylase is an enzyme found in saliva, and its main role during digestion is to break down starches (complex carbohydrates) into simple sugars like maltose. When you chew food, amylase begins the process of chemical digestion, starting to break down starches in the mouth before the food moves to the stomach. What is the role of pepsin? Describe using a diagram what it does during digestion. Pepsin is an enzyme found in the stomach that breaks down proteins into smaller molecules called peptides. Pepsin is activated in the acidic environment of the stomach and works best in this acidic condition. What 2 important substances are found in the gastric juice of the stomach? Hydrochloric acid and pepsinogen (inactive form of pepsin – which is activated in the acidic environment of the stomach to pepsin). What is the pH of the acid in the stomach? Why is this important for digestion? The pH of the acid in the stomach typically ranges from 1.5 to 3.5, making it highly acidic. This acidic environment is crucial for several reasons. First, it activates pepsinogen into pepsin, an enzyme that breaks down proteins. The acidity also helps kill harmful bacteria and pathogens that may be present in food, preventing infection. Identify the enzyme that breaks down fats and oils. The enzyme that breaks down fats and oils is called lipase. Lipase is produced mainly in the pancreas and secreted into the small intestine, where it breaks down fats into fatty acids and glycerol. Objective: Identify and label each organ in the digestive system and relate their function to the overall role in the digestive system. Can you label each organ of the digestive system? Include a diagram. What happens in the oesophagus during peristalsis? During peristalsis, the oesophagus moves food from the mouth to the stomach through rhythmic contractions of its muscles. These contractions push the food in a wave-like motion, helping it move down the oesophagus and into the stomach. What happens during digestion in the stomach? In the stomach, food is mixed with gastric juices, which contain hydrochloric acid and the enzyme pepsin. The acid helps break down food and kills bacteria, while pepsin begins the process of protein digestion. The stomach muscles also churn the food, turning it into a semi-liquid mixture called chyme before it moves to the small intestine. Identify the organs that involve the secretion of the following enzymes: amylase, pepsin and lipase. Amylase: secreted by the salivary glands in the mouth, and the pancreas. Pepsin: secreted by the stomach Lipase: secreted by the pancreas How long is the small intestine? The small intestine is about 6 metres long. List and outline the role of the three segments of the small intestine during digestion. The small intestine is made up of three segments: the duodenum, jejunum, and ileum. The duodenum is the first part, where most of the chemical digestion occurs. It receives bile from the liver and digestive enzymes from the pancreas to break down fats, proteins, and carbohydrates. The jejunum, the middle section, is where most nutrient absorption takes place, allowing the body to absorb vitamins, minerals, and other nutrients. The ileum, the last part of the small intestine, continues nutrient absorption, specifically of vitamin B12 and bile salts, before the remaining waste moves into the large intestine. Each section plays an important role in the digestion and absorption process. Why are villi in the small intestine important? Villi are tiny finger-like projections in the lining of the small intestine. They increase the surface area for absorption, allowing nutrients to pass into the bloodstream more efficiently. This helps the body absorb vitamins, minerals, and other nutrients from digested food. What organ produces or makes bile? Liver Which organ stores bile? Gallbladder What is the role of bile in digestion? Bile helps digest fats by emulsifying them, which means it breaks large fat droplets into smaller ones. This makes it easier for enzymes like lipase to further break down the fat into fatty acids and glycerol, which can be absorbed in the small intestine. What is the role of the pancreas? The pancreas produces digestive enzymes like amylase, lipase, and proteases, which are released into the small intestine to break down carbohydrates, fats, and proteins. The pancreas also secretes bicarbonate to neutralise stomach acid, creating a more suitable environment for digestion in the small intestine. Why is the appendix considered an important part of the bowel’s immune system? The appendix contains lymphatic tissue and plays a role in immune function, particularly in the development of gut immunity. It helps protect the body from infections and supports the healthy balance of bacteria in the intestines. How long is the large intestine? Around 1.5 metres long. What is the main function of the large intestine? The main function of the large intestine is to absorb water and electrolytes from the remaining indigestible food matter. This helps form solid waste, which is eventually expelled from the body. What do faeces mainly contain? Faeces mainly consist of water, undigested food particles (like fibre), bacteria, cells shed from the lining of the intestines, and waste products from digestion. Experimental Processes How do you test for the following: - Simple sugars (monosaccharides) You can use Benedict’s solution and heat the sample; if it changes colour from blue to orange/red, simple sugars are present. - Disaccharides You can use Benedict’s solution after hydrolysing the disaccharide (by adding acid and heating) to break it down into monosaccharides, then heating it to see a colour change. - Polysaccharides You can use iodine solution, which turns blue-black when it reacts with starch (a polysaccharide). How do you test for fats and oils? The Sudan III test for fats and oils works by adding Sudan III dye to the sample. Sudan III is a red dye that binds to fats and oils, causing them to stain. If fats or oils are present, the sample will form a red-stained layer or show red streaks. This indicates that lipids are present in the sample. Or, rub on brown paper, if transparent then fat/oil is present. How do you test for proteins? You can use Biuret solution, which turns purple when proteins are present. Key Science Skills Can you graph data? Bar graph vs. line graph What goes on the x-axis of a graph? The x axis of a graph typically represents the independent variable. This is the variable that you, as the experimenter, change or manipulate during the experiment. What goes on the y-axis of a graph? The y axis represents the dependent variable. This is the variable that you measure or observe in response to changes in the independent variable. What is an independent variable? The factor or condition that is deliberately changed or manipulated in an experiment. It is what you are testing or investigating to see how it affects the dependent variable. What is a dependent variable? The factor that is measured or observed in an experiment. It depends on the changes made to the independent variable, and it shows the outcome or effect of the experiment. What is the difference between an aim of an experiment and a hypothesis? The aim of an experiment is a statement that describes the purpose or goal of the experiment, outlining what the researcher intends to find or discover. The hypothesis is a specific prediction about what the researcher expects to happen based on prior knowledge or theory. It is a testable statement that suggests a relationship between the independent and dependent variables. Digestion Review Questions 1. Define each of the following: Digestion Digestion is the process where the body breaks down food into smaller molecules that can be absorbed and used for energy. Ingestion Ingestion is the act of taking in food and liquids through the mouth. Egestion Egestion is the removal of undigested food and waste from the body in the form of faeces. Emulsify Emulsify is the process of breaking down large fat droplets into smaller ones to help with digestion. 2. Match the types of teeth with their specific function: Canines Incisors Molars & Premolars Biting and cutting food Incisors Grinding and crushing food Molars & premolars Tearing and grasping food Canines 3. Identify the different types of teeth as being one of the following: incisors, canines, molars or premolars. Pre- Molars Incisors Molars Canines 4. Describe the function of saliva. Saliva helps moisten food, making it easier to chew and swallow. It also contains the enzyme amylase, which starts the process of breaking down starches into simpler sugars. Additionally, saliva helps protect the mouth from infections and keeps the mouth moist. 5. Name the enzyme found in saliva. Amylase 6. Is chewing food an example of mechanical or chemical digestion? Explain. Mechanical digestion as it breaks food down into smaller pieces by tearing, grinding and crushing food. 7. State the name of the: a. Type of digestion that involves enzymes. Chemical digestion b. Enzymes that break down fats. Lipase c. Enzymes that break down proteins. Pepsin 8. Explain why it is important to break down the food that we eat. It is important to break down the food we eat so that the body can absorb essential nutrients like vitamins, minerals, and energy from the food. If food isn't broken down, the body can't use it properly. 9. Describe what happens to enzymes when they get too hot. High temperatures can cause the enzyme's active site to lose its shape, preventing it from binding to the substances it needs to break down so they no longer work properly. 10. State the food group that glucose belongs to. Carbohydrates 11. Name the type of acid that is found in the human stomach. Hydrochloric acid 12. Define ‘chyme’. Chyme is the partially digested, semi‐liquid food that leaves the stomach and enters the small intestine. It is created when food mixes with stomach acids and digestive enzymes. 13. The pH of the stomach is around 1.5. a. Compare the pH of the stomach to vinegar. Stomach acid is more acidic with a pH of around 1, compared to vinegar with a pH of around 3. b. Explain why you think the pH of the stomach is so strong. The pH of the stomach is strong (acidic) to help break down food and activate enzymes like pepsin, which are essential for protein digestion. The acidity also helps kill harmful bacteria and pathogens that may be present in food, protecting the body from infections. 14. Describe the process of peristalsis and suggest why it occurs. Peristalsis is a series of wave‐like muscle contractions that move food through the digestive tract, from the oesophagus to the stomach and then through the intestines. This process occurs to push food along the digestive system, helping break it down and absorb nutrients efficiently. It ensures that food moves in the correct direction and prevents it from going backwards. 15. What is bile? Where is it made? Where is it stored? What is the function of bile? Bile is a digestive fluid that helps break down fats. It is made in the liver and stored in the gallbladder. The function of bile is to emulsify fats, which means breaking large fat droplets into smaller ones, making it easier for enzymes to digest the fat. 16. Use the image below to explain why emulsification is important in digestion. Emulsification is important in digestion because it breaks large fat droplets into smaller ones, increasing the surface area for enzymes like lipase to act on. This makes it easier for the body to digest and absorb fats, allowing nutrients to be efficiently absorbed in the small intestine. 17. Where does emulsification occur in the digestive tract and what causes it? Emulsification occurs in the small intestine, where bile from the liver helps break down large fat droplets into smaller ones. Bile acts as an emulsifier, causing the fats to mix more easily with water and allowing digestive enzymes to further break down the fats. 18. The photomicrograph shows a section of the wall of the small intestine. a. What happens in this part of the digestive system? This is where vital nutrients are absorbed into the bloodstream via villi. b. Identify B and explain how B increases the efficiency of the function of this part of the digestive system. In the small intestine, villi and microvilli play a key role in absorbing nutrients. Villi are tiny, finger‐like projections that line the walls of the small intestine, increasing the surface area for absorption. On the surface of the villi, there are even smaller projections called microvilli, which further increase the surface area. This structure allows for more efficient absorption of nutrients, such as vitamins, minerals, and other small molecules, into the bloodstream. c. Suggest why it is necessary to drink fluids when you suffer from diarrhoea. It is necessary to drink fluids when you suffer from diarrhoea because the body loses a significant amount of water and electrolytes, such as sodium and potassium, through frequent stools. Drinking fluids helps replace these lost fluids, preventing dehydration and helping maintain proper body function. 19. Describe the relationship between: a. Teeth and mechanical digestion. Teeth play a key role in mechanical digestion by physically breaking down food into smaller pieces through chewing. This increases the surface area of food, making it easier for digestive enzymes to act on it. b. The pancreas and the small intestine. The pancreas produces digestive enzymes (like amylase, lipase, and proteases). These enzymes are released into the small intestine, where they help break down carbohydrates, fats, and proteins. c. The liver, gall bladder and the small intestine. The liver produces bile, which is stored in the gall bladder. When food enters the small intestine, the gall bladder releases bile into the small intestine, where it emulsifies fats, helping them to be digested by enzymes. d. The villi, small intestine and capillaries. The villi are tiny projections lining the small intestine that increase the surface area for nutrient absorption. Each villus contains capillaries that absorb nutrients like amino acids, sugars, and vitamins from the digested food into the bloodstream, allowing them to be transported to the rest of the body. e. Bile, lipase and fats. Bile, produced by the liver and stored in the gall bladder, emulsifies large fat droplets, breaking them into smaller droplets. This increases the surface area for lipase, an enzyme produced by the pancreas, to break down fats into fatty acids and glycerol, making them easier to absorb. 20. The following diagram shows the intestine and a blood vessel. Use the diagram to write a statement describing how food passes into the bloodstream. In the small intestine, food is absorbed into the bloodstream through tiny hair‐like structures called villi, which line the walls of the intestine. Each villus contains small blood vessels called capillaries. As food is digested into nutrients (like amino acids, sugars, and fatty acids), these nutrients pass through the cells of the villi. The cells of the villi have tiny openings that allow the nutrients to enter the capillaries. Once inside the capillaries, the nutrients are carried away by the blood and transported to various parts of the body where they are used for energy, growth, and repair. 21. The statements below all describe what happens at different parts of the digestive system. Match each of the following words with one of the statements. Mouth Stomach Duodenum Small Intestine Large Intestine A Water, vitamins and minerals are absorbed. Large intestine B Bile from the liver and gall bladder emulsifies fat into small droplets. Duodenum C Food is mixed with into a soupy mixture with acids and enzymes. Stomach D Food is mechanically broken down into smaller pieces. Mouth E Digested nutrients diffuse through the wall into the bloodstream. Small intestine 22. State the name of the: A Organ in which the digestive process begins. Mouth B Type of digestion in which enzymes secreted by your salivary glands are involved in. Chemical C Slimy, slippery ball‐shape in which your tongue rolls food. Bolus D Muscular contractions that push the ball‐shaped food through the oesophagus to the stomach. Peristalsis E Organ in which most of the absorption of nutrients occurs. Small Intestine F Finger‐shaped structures through which nutrients are absorbed in the organ above. Villi 23. Match the organ with its function in the table shown: Gall Bladder Large Intestine Liver Oesophagus Pancreas Rectum Small Intestine Stomach A Where the breakdown of starch and protein is finished and fat breakdown occurs. Small Intestine B Temporary storage of food and where protein digestion begins. Stomach C Tube that takes food from mouth to stomach. Oesophagus D Stores undigested food and waste while bacteria make some vitamins. Large Intestine E Stores faeces. Rectum F Makes enzymes used in the small intestine. Pancreas G Makes bile, stores glycogen and breaks down toxins. Liver H Stores bile made in the liver until needed in the small intestine. Gall Bladder 24. There are three sections of the small intestine. Match each section with the accurate descriptions. Jejunum Duodenum Ileum A About 25cm Duodenum B The first section of the small intestines. Duodenum C The second section of the small intestines. Jejunum D About 2.5 metres. Jejunum E Primary site where chemical digestion begins. Duodenum F The third section of the small intestines. Ileum G Absorbs any remaining nutrients. Illeum H About 3.5 metres. Illeum I Primarily responsible for absorbing nutrients (contains villi and microvilli to increase surface area for absorption). Jejunum 25. Describe digestion by placing words from the table in the gaps in the following extract. Absorb Digestion Saliva Cells Repair Tract Nutrients Pancreas Digestion is the process of breaking down complex foods into simple nutrients that the body can absorb. The body’s cells need these nutrients for energy, as well as for building materials so the cells can grow and repair themselves. The digestive system consists of: • The digestive tract ‐ series of tubes and cavities that food passes through as it is broken down, and • Other organs that help with digestion, such as the saliva glands, liver and pancreas. The digestive system doesn’t just help with digestion. It is also involved in feeding, absorption and elimination. Reading Comprehension: Read the extract below and use the information to answer the questions. • Highlight key points • Annotate to add information/identify areas to find more information about. Vital Nutrients Carbohydrates play a key role in providing energy for the body. They are the body's primary source of fuel, especially for the brain and muscles during physical activity. Carbohydrates are found in foods like grains, fruits, and vegetables, and they are broken down into glucose, which the body uses for energy. A balanced diet should include carbohydrates, making up about 45‐65% of total daily intake. It's important to choose complex carbohydrates, such as whole grains and vegetables, which provide more nutrients and fibre than simple sugars. Proteins are essential for building and repairing tissues in the body, including muscles, skin, and organs. They are made up of amino acids, some of which the body cannot produce on its own, meaning they must be obtained through food. Protein is also crucial for immune function and the production of hormones and enzymes. Foods like meat, fish, eggs, beans, and nuts are good sources of protein. Protein should account for around 10‐35% of daily calorie intake to support growth, repair, and overall body function. Fats are necessary for energy storage, insulation, and the protection of vital organs. They also play a role in absorbing certain vitamins, such as A, D, E, and K, which are fat‐soluble. Fats come in various forms, including unsaturated fats, which are found in foods like avocados, nuts, and olive oil, and saturated fats, which are found in foods like butter and fatty cuts of meat. A healthy diet should include fats that make up about 20‐35% of daily intake, with a focus on unsaturated fats and limiting the intake of saturated fats to help maintain heart health. Vitamins are organic compounds that the body needs in small amounts for various functions, including immune support, energy production, and bone health. Each vitamin has specific roles; for example, Vitamin C helps with tissue repair, while Vitamin D is important for calcium absorption. Fruits, vegetables, dairy products, and fortified foods are common sources of vitamins. A well‐balanced diet should provide all the necessary vitamins, but there is no exact percentage for vitamin intake, as needs vary based on individual health and activity levels. Minerals are inorganic substances that are vital for processes such as building bones, transmitting nerve impulses, and maintaining heart function. Important minerals include calcium, iron, potassium, and magnesium, which can be found in foods like dairy products, meats, leafy greens, and whole grains. Like vitamins, there isn't a single recommended percentage for mineral intake, but consuming a wide variety of nutrient‐dense foods can ensure adequate mineral intake to support overall health. Water is the most important component of the diet, as it supports every cell and system in the body. Water helps regulate body temperature, remove waste products, and maintain proper digestion and nutrient absorption. While there is no exact percentage of intake for water, a general recommendation is to drink about 8 cups (2 litres) per day, though this can vary depending on factors like activity level, climate, and individual needs. Staying hydrated is essential for overall health and well‐being. 1. Outline the importance of carbohydrates in a healthy diet. Carbohydrates are the body's main source of energy. They are broken down into glucose, which fuels the body's cells, muscles, and brain. Eating enough carbohydrates helps maintain energy levels, supports physical activity, and ensures the proper functioning of the nervous system. 2. How do proteins support the body, and what types of food are good sources of protein? Proteins are essential for building and repairing tissues, making enzymes and hormones, and supporting immune function. Good sources of protein include meat, poultry, fish, eggs, dairy products, beans, lentils, and nuts. 3. What role do fats play in the body? Fats are important for storing energy, protecting organs, and helping absorb fat‐soluble vitamins (A, D, E, and K). They also play a role in maintaining healthy skin and regulating body temperature. Healthy fats can be found in foods like avocados, olive oil, nuts, and fatty fish. 4. How do vitamins contribute to the body’s function, and how can they be obtained from food? Vitamins are essential for a range of bodily functions, including immune support, energy production, and maintaining healthy skin and vision. They can be obtained from a variety of foods, such as fruits, vegetables, dairy products, and whole grains. 5. What are the key functions of minerals in the body, and how can we ensure we are getting enough minerals in our diet? Minerals help with building strong bones and teeth, nerve function, and muscle contraction. They are also important for fluid balance and maintaining a healthy heart. To ensure enough minerals, include a variety of foods like dairy products, leafy greens, nuts, seeds, and meats in your diet. 6. Why is water considered the most important component of the diet, and how much should we aim to drink each day? Water is vital for regulating body temperature, transporting nutrients, and removing waste products. It also aids digestion and keeps the skin healthy. The recommended daily intake varies, but generally, adults should aim to drink about 2 to 2.5 litres (8‐10 cups) of water each day. 7. Identify the recommended daily intake for the nutrients below: Carbohydrates 45 ‐ 65% Protein 10 ‐ 35% Fats 20 ‐ 35% 8. Choose ONE meal that you have consumed this week for dinner. Identify the food sources that contain the following nutrients: Nutrients: Food Source: Carbohydrates Protein Fats Example: Meal ‐ Scrambled eggs on toast with butter Nutrients: Food Source: Carbohydrates 2 x pieces of toast Protein 2 x eggs Milk Fats Butter 9. Using the same meal as above, identify if any of the food sources contained the vitamins and minerals listed below: This will require you to research each food item for the vitamins and minerals it contains. Vitamins & Minerals: Food Source: Purpose in Diet: Vitamin A Vitamin C Vitamin B (Group) Calcium Iron Potassium Example: Meal – scrambled eggs on toast Vitamins & Minerals: Food Source: Purpose in Diet: Vitamin A Eggs, butter Vitamin C Vitamin B (Group) Milk, eggs, butter, bread Calcium Milk, bread Iron Bread Potassium Milk, bread 10. Plan a meal: Your final task is to create a meal (breakfast, lunch or dinner) that includes the vital nutrients that you require in your diet. Meal Ingredients For each ingredient, identify the nutrient(s) that it contains: Food Source: Nutrient(s): Example: Bread Carbohydrates, vitamins (B), minerals (calcium, iron, potassium) Vitamin and Mineral Deficiency Scenario 1: A 25‐year‐old woman who feels very tired all the time, even after getting a full night of sleep. She also notices her skin looks pale and her fingernails are brittle and often break easily. The patient likely has a/an iron deficiency. Evidence: Iron is essential for producing haemoglobin in red blood cells, which carries oxygen throughout the body. A lack of iron can lead to iron‐deficiency anaemia, causing fatigue, pale skin, brittle nails, and other symptoms. Iron deficiency is a common cause of tiredness. Scenario 2: A 30‐year‐old woman who has difficulty seeing in low light, especially at night. She also complains that her skin is dry, and her immune system seems weaker than usual, making her catch colds more easily. The patient likely has a/an Vitamin A deficiency. Evidence: Vitamin A is crucial for maintaining healthy vision, particularly in low light (a condition known as night blindness). It also supports healthy skin, and plays a role in strengthening the immune system. A deficiency in vitamin A can lead to dry skin, a weakened immune response, and poor vision in dim lighting. Scenario 3: A 60‐year‐old man who has been feeling weak and fragile lately. He has noticed some pain in his bones, especially in his lower back, and he often gets fractures from minor falls. He rarely goes outside and does not drink much milk. The patient likely has a/an calcium deficiency. Evidence: Calcium is crucial for maintaining strong bones and teeth, and when calcium levels are low, it can lead to weakened bones, pain, and a higher risk of fractures, especially in older adults. Scenario 4: A 19‐year‐old college student who has noticed that his gums are bleeding when he brushes his teeth. He also has small red spots on his skin and has been feeling more tired than usual. Additionally, he’s had trouble healing from a recent wound on his arm, which seems to be taking longer than normal to close. The patient likely has a/an Vitamin C deficiency. Evidence: Vitamin C is essential for the production of collagen, which is vital for healthy skin, blood vessels, and connective tissues. A lack of vitamin C can lead to weakened blood vessels, causing easy bruising, red spots on the skin (petechiae), bleeding gums, and poor wound healing. Scenario 5: A 30‐year‐old woman who frequently experiences back pain and has noticed her posture is becoming more hunched over time. She has also been feeling weaker, especially in her legs, and is worried about her bones. She doesn't drink milk and rarely eats dairy products, and she spends most of her time indoors. The patient likely has a/an Vitamin D deficiency. Evidence: Vitamin D is necessary for the body to absorb calcium properly, and without enough vitamin D, even if calcium is consumed, it may not be properly utilized. The woman's lack of dairy intake and limited time spent outdoors, where sunlight helps the body produce vitamin D, could be contributing to this deficiency. Scenario 6: A 50‐year‐old man who has been feeling weak, dizzy, and has trouble concentrating at work. He also complains about irregular heartbeats, especially after exercising, and sometimes feels a cramping sensation in his legs. The patient likely has a/an Potassium deficiency. Evidence: Potassium is an essential mineral that helps regulate fluid balance, muscle contractions, and nerve signals, including those related to the heart. Low potassium levels can lead to muscle cramps, weakness, dizziness, and irregular heart rhythms (arrhythmias), particularly after physical exertion. Reading Comprehension: Read the extract below and use the information to answer the questions. Effect of pH on Enzyme Activity Pepsin is an important enzyme in the stomach that helps break down proteins from the food we eat. However, pepsin only works well when the stomach is very acidic. The level of acidity in the stomach is measured by pH, which can range from 0 (very acidic) to 14 (very basic or alkaline). The normal pH in a healthy stomach is between 1.5 and 3.5, which is very acidic. When food enters the stomach, the stomach produces a substance called pepsinogen, which is the inactive form of pepsin. Pepsinogen needs to be turned into active pepsin in order to start breaking down proteins. For pepsinogen to change into pepsin, the stomach needs to be very acidic. This happens when the stomach produces hydrochloric acid (HCl), which lowers the pH to a very acidic level. When the pH is low enough (around 1.5 to 3.5), pepsinogen is activated and turns into pepsin. Once activated, pepsin can start breaking down proteins into smaller parts called peptides. However, if the stomach is not acidic enough (if the pH is higher, like 4 or above), pepsin will not work as well. The enzyme becomes less active and cannot break down proteins as efficiently. 1. Pepsin, unlike amylase and lipase, is only released in the stomach. Explain why pepsin is released in the stomach with reference to the information above. Pepsin is released in the stomach because it is an enzyme that works best in the highly acidic environment of the stomach. It is secreted as an inactive form called pepsinogen, which is then activated by the low pH (acidic conditions) in the stomach. Amylase and lipase, on the other hand, are released in the mouth and small intestine, where the pH is more neutral or slightly alkaline, which is better suited for their activity. 2. What is the role of hydrochloric acid in activating pepsinogen? Hydrochloric acid (HCl) in the stomach provides the highly acidic environment needed to activate pepsinogen, converting it into its active form, pepsin. The low pH (around 1.5 to 2) denatures pepsinogen, allowing it to unfold and activate into pepsin, which then starts breaking down proteins in food. 3. What is the normal pH level for the stomach? The normal pH level for the stomach is typically between 1.5 and 3.5. This acidic environment is crucial for activating enzymes like pepsin and for breaking down food effectively. 4. Taking an antacid can influence the pH level of the acid in the stomach, with strong antacids temporarily raising the pH to 5 – 6. What would effect would this have on digestion during this time? If the pH of the stomach rises to 5–6 due to antacid use, it could impair the digestive process. Pepsin, which works best at a very low pH, would become less effective or inactive at this higher pH level. This would slow down the digestion of proteins, as pepsin plays a key role in protein breakdown. Additionally, the activation of other enzymes that require a low pH, like those in the stomach, could also be affected. 5. What does this information suggest about the pH requirements for the activation of amylase and lipase? Note: To answer this question you will need to know where amylase and lipase are released in the digestive system. Amylase and lipase work best at a more neutral or slightly alkaline pH. Amylase is released in the mouth (and the small intestine) and works best at a neutral pH around 7, while lipase is released in the small intestine, where the pH is slightly alkaline (around 7.5 to 8.5). This suggests that unlike pepsin, which requires an acidic environment for activation, amylase and lipase function in more neutral or slightly alkaline conditions found in the mouth and small intestine. Reading Comprehension: Read the extract below and use the information to answer the questions. The Importance of a Healthy Gut – The Gut‐Brain Axis The gut‐brain axis is the connection between your brain and your gut (the stomach and intestines). This link is important because what happens in your gut can affect how you feel, think, and behave, and vice versa. The brain sends messages to the gut using the nervous system. It controls things like digestion, how fast food moves through your intestines, and how much stomach acid is produced. This is done through the vagus nerve, which is a super‐fast communication line between the brain and gut. The gut can also send signals to the brain. It has its own special system of nerves called the enteric nervous system, sometimes called the "second brain." This system controls digestion and can send messages about hunger, feelings of fullness, and even stress. The gut is also home to millions of tiny bacteria called the microbiome, which can influence the brain. These bacteria produce chemicals that can affect your mood, energy, and even mental health. The bacteria in your gut can produce chemicals like serotonin (which helps regulate mood) and dopamine (which affects motivation and happiness). When the gut microbiome is healthy (balanced), it helps produce these chemicals, making you feel good. But if the gut is unhealthy (imbalanced), it can lead to problems like anxiety, depression, or stress. For example, a diet full of junk food can make the gut microbiome unhappy, and this could affect your brain and how you feel. When you're stressed, your brain sends signals to the gut, which can cause stomach‐aches, nausea, or changes in appetite. On the other hand, if your gut is upset (like when you're sick or have a bad diet), it can make you feel more stressed or anxious. This is why stress and tummy problems are often linked. Taking care of your gut is really important for both your body and your mind. Eating a balanced diet with lots of fibre, fruits, vegetables, and good bacteria (like yogurt) can help keep your gut microbiome happy. This can lead to better mood, less stress, and better overall health. 1. What is the gut‐brain axis? The gut‐brain axis is the connection between your brain and your gut (stomach and intestines). This link is important because what happens in the gut can impact how you feel, think, and behave, and vice versa. 2. How does the brain communicate with the gut? The brain communicates with the gut through the nervous system, controlling digestion, the speed of food movement through the intestines, and stomach acid production. This is done via the vagus nerve, a fast communication line between the brain and the gut. 3. What is the vagus nerve and what role does it play in the gut‐brain axis? The vagus nerve is a crucial communication pathway between the brain and the gut. It plays a role in controlling digestion, the speed at which food moves through the intestines, and the production of stomach acid. 4. What is the ‘second brain’ in the gut, and what does it do? The ‘second brain’ in the gut is the enteric nervous system, a system of nerves that controls digestion. It can also send messages about hunger, feelings of fullness, and even stress, influencing how we feel. 5. How do gut bacteria affect the brain? Gut bacteria can influence the brain by producing chemicals such as serotonin and dopamine, which regulate mood, energy, and mental health. A balanced gut microbiome helps produce these chemicals, making you feel better, while an imbalanced one can negatively affect your mood and mental health. 6. What chemicals produced by the gut can influence your mood and mental health? The gut produces serotonin (which helps regulate mood) and dopamine (which affects motivation and happiness), both of which can influence your mood and mental well‐being. 7. How can an unhealthy gut impact your brain and emotions? An unhealthy or imbalanced gut can lead to mental health issues such as anxiety, depression, or stress. When the gut microbiome is disrupted, it can negatively impact the production of chemicals like serotonin and dopamine, which can affect your emotions and mood. 8. Why can stress cause stomach issues or changes in appetite? Stress can trigger the brain to send signals to the gut, which can lead to stomach aches, nausea, and changes in appetite. This is because the brain and gut are closely linked, and stress can disrupt digestion and gut function. 9. Research: What is meant by ‘gut microbiome’? What does it mean when the gut microbiome is balanced/imbalanced? The gut microbiome refers to the community of bacteria and other microorganisms living in the gut. A balanced microbiome is when the community of bacteria is varied When the gut microbiome is balanced, it means that the beneficial bacteria in your gut are thriving and in the right proportions. This balance helps support healthy digestion, immune function, and the production of important chemicals like serotonin and dopamine, which regulate mood and mental health. A balanced microbiome generally leads to better overall health, including improved mood, energy levels, and reduced risk of conditions like anxiety and depression. When the gut microbiome is imbalanced, it means that harmful bacteria or pathogens may have overtaken the beneficial bacteria, disrupting the gut's natural balance. This imbalance can interfere with digestion, nutrient absorption, and the production of vital brain chemicals. An imbalanced microbiome can contribute to digestive issues, weakened immune function, and even mental health problems like anxiety, depression, or stress. 10. List some ways to keep microbiome in your gut healthy. To keep your gut microbiome healthy, eat a balanced diet rich in fiber, fruits, vegetables, and probiotics (like yogurt). These foods help nourish the beneficial bacteria in your gut, supporting better mood and overall health. 11. How does a poor diet affect both your gut and your brain? A poor diet, especially one high in junk food, can upset the balance of the gut microbiome, which can then negatively affect your brain and emotions. This imbalance can lead to mood disorders like anxiety and depression, as well as affect overall mental well‐being. Reading Comprehension: Read the extract below and use the information to answer the questions. Research Study One The Effect of Probiotics on Anxiety and Depression in Individuals with Gastrointestinal Disorders The study investigated whether taking probiotics (beneficial bacteria) could improve symptoms of anxiety and depression in people who have gastrointestinal (GI) disorders. Researchers wanted to understand if the gut microbiome influences mood and mental health. This study involved 70 participants with GI disorders, such as irritable bowel syndrome (IBS). Half of the participants were given a daily dose of probiotics for 8 weeks, while the other half were given a placebo (a non‐active pill). Before and after the study, the participants completed surveys to measure their levels of anxiety, depression, and GI symptoms. They also had blood samples taken to analyse inflammatory markers and gut health. The results showed that the group who took probiotics had significant improvements in their anxiety and depression symptoms compared to the placebo group. Additionally, the probiotic group reported a decrease in GI symptoms, and blood tests indicated lower levels of inflammation. The study suggests that improving gut health through probiotics may have positive effects on mental health, particularly for individuals with both gastrointestinal issues and mood disorders. 1. What was the aim of the study? The aim of the study was to investigate whether taking probiotics (beneficial bacteria) could improve symptoms of anxiety and depression in people with gastrointestinal (GI) disorders, and to understand if the gut microbiome influences mood and mental health. 2. Identify the independent variable in the study. The independent variable in the study was the daily dose of probiotics, as it was the factor being manipulated to see its effect on anxiety, depression, and GI symptoms. 3. What is a placebo? Why do you think researchers used a placebo in this study? A placebo is a non‐active pill or treatment that looks identical to the actual treatment but has no therapeutic effect. Researchers used a placebo in this study to control for the psychological effect of believing one is receiving treatment (the placebo effect) and to ensure that any changes observed were due to the probiotics and not other factors. 4. Why would diet be difficult to implement as a controlled variable in this study? Diet would be difficult to implement as a controlled variable because it can vary widely among individuals, and participants may have different eating habits or dietary restrictions that could affect gut health and mental health. Ensuring everyone followed the same diet would be challenging and could introduce bias or inconsistencies. 5. How did the researchers measure the participants’ anxiety and depression? The researchers measured the participants' anxiety and depression through surveys completed before and after the study. 6. What were the results of the study for the group taking probiotics? The results showed that the group taking probiotics had significant improvements in their anxiety and depression symptoms compared to the placebo group. They also reported a decrease in GI symptoms, and blood tests indicated lower levels of inflammation. 7. What are the potential implications of this study? (How could the results of this study help people with gastrointestinal disorders?) The potential implications of this study suggest that improving gut health through probiotics may have positive effects on mental health, especially for individuals who suffer from both gastrointestinal issues and mood disorders. The results could lead to the use of probiotics as a complementary treatment for anxiety, depression, and GI symptoms in these individuals, offering a possible alternative or addition to traditional mental health treatments. Reading Comprehension: Read the extract below and use the information to answer the questions. Research Study Two The Role of the Gut‐Brain Axis in Stress and Gut Function This study explored how stress affects gut function and how the brain and gut communicate during stressful situations. Researchers wanted to understand how stress might influence the gut‐brain axis and whether certain changes in gut function could be linked to feelings of stress. The study involved 40 healthy adults who were asked to participate in a stress‐inducing task (public speaking). Before and after the task, researchers measured various physical responses like heart rate and blood pressure. They also collected stool samples to analyse changes in gut microbiota and used questionnaires to assess the participants' emotional state (levels of stress). Additionally, brain scans were used to observe changes in brain activity during the stressful task. The study found that stress had a noticeable effect on both the gut and the brain. Participants showed a shift in their gut microbiota after the stressful task, with an increase in harmful bacteria and a decrease in beneficial bacteria. These changes were linked to higher stress levels. The brain scans showed increased activity in regions of the brain related to stress and emotion. This suggests that stress can alter the gut microbiome and that the gut‐brain axis plays an important role in how stress affects both the mind and body. 1. What was the aim of the study? The aim of the study was to explore how stress affects gut function and how the brain and gut communicate during stressful situations. The researchers wanted to understand how stress might influence the gut‐brain axis and if changes in gut function could be linked to feelings of stress. 2. What method(s) were used to measure stress in the participants? How accurate do you think these measurements would be? Why? Stress was measured using a combination of physical responses (heart rate and blood pressure), stool samples to analyse changes in gut microbiota, questionnaires to assess emotional stress levels, and brain scans to observe changes in brain activity. These methods are likely accurate as they use both physiological (heart rate, blood pressure) and psychological (questionnaires, brain scans) measurements to provide a comprehensive view of how stress affects the body and mind. 3. What changes in the gut microbiota were observed after the stressful task? After the stressful task, there was a noticeable shift in the gut microbiota. There was an increase in harmful bacteria and a decrease in beneficial bacteria. These changes were linked to higher levels of stress. 4. What is the significance of brain activity being measured during a stressful task? Measuring brain activity during a stressful task is significant because it provides insights into how the brain responds to stress and how this may influence emotional and physical responses. Brain scans showing increased activity in regions related to stress and emotion help researchers understand how stress affects both the mind and body, particularly through the gut‐brain axis. 5. How can changes in the gut microbiome affect overall health, based on the study’s results? Changes in the gut microbiome, such as an increase in harmful bacteria and a decrease in beneficial bacteria, can negatively affect overall health. Based on the study’s results, these changes can contribute to digestive issues, immune system dysfunction, and even mental health problems, as the gut and brain are interconnected through the gut‐brain axis. 6. An increase in harmful bacteria in the gut can lead to digestive issues such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). How might the results of this study impact how medical professionals treat a person with IBD and IBS? The results of this study suggest that stress can negatively affect the gut microbiome, potentially worsening conditions like IBD and IBS. Medical professionals might take these findings into account by addressing stress management as part of treatment plans for patients with these conditions. This could involve recommending stress‐reduction techniques, therapy, or probiotics to help manage both the emotional and gastrointestinal aspects of IBD and IBS. Reading Comprehension: Read the extract below and use the information to answer the questions. Digestive Differences The digestive systems of humans, herbivores, and carnivores have some important differences based on the types of food they eat. Humans are omnivores, meaning they eat both plants and animals. Our digestive system is designed to process a variety of foods. We have a relatively short small intestine and stomach compared to herbivores, which allows us to digest a wide range of foods, including both meat and plants. Our stomach is acidic, which helps break down proteins from meat, and we also have enzymes that help digest carbohydrates and fats. In contrast, herbivores, like cows, have a much longer digestive system break down the tough plant materials they eat. Herbivores often have a specialised stomach with multiple chambers. For example, cows have four stomach chambers that allow them to ferment and break down cellulose, a tough fibre found in plants. They also chew their food multiple times to help digest it properly. This is very different from humans, who only have one stomach chamber and don’t need to ferment food to the same extent. The digestive system of horses is different from both humans and cows, mainly due to their herbivorous diet, which consists primarily of fibrous plant material. Like cows, horses rely on the breakdown of plant fibre, but they have a single‐chambered stomach, similar to humans, instead of a multi‐chambered stomach like cows. While humans also have a relatively short digestive tract compared to herbivores, horses have a longer caecum and large intestine, which play a crucial role in fermenting and breaking down cellulose from plants. This makes their digestive system more similar to that of non‐ruminant herbivores (have single chamber stomachs), where fermentation occurs after food passes through the stomach, rather than in a specialized stomach chamber. Unlike cows, who are ruminant herbivores (have multiple chamber stomachs) which ferment food in their stomachs before it is further digested, horses process food mainly in the cecum and colon, which allows for a more continuous, rather than regurgitative, digestion process. This difference is important because it means horses need to eat smaller amounts of food throughout the day to ensure a steady flow of nutrients, while cows can graze and ferment food in larger, less frequent meals. Carnivores, like lions, have a digestive system that is adapted to eating meat. They have a shorter digestive tract because meat is easier to digest than plants. Their stomach is highly acidic and contains powerful enzymes that help break down the proteins in meat. Unlike herbivores, carnivores don’t need to break down tough fibre, so they don’t have a long small intestine. The digestive systems of herbivores, carnivores, and humans are all specialized for their diets, helping them get the nutrients they need to survive. 1. What type of diet do humans have, and how is their digestive system suited for this diet? Humans are omnivores, meaning they eat both plants and animals. Our digestive system is designed to process a variety of foods. We have a relatively short small intestine and stomach, which allows us to digest both meat and plant‐based foods. Our stomach is acidic, helping break down proteins from meat, and we also have enzymes that assist in digesting carbohydrates and fats. 2. Explain the difference between the digestive system of ruminant and non‐ruminant herbivores. Ruminant herbivores, like cows, have a specialized digestive system with multiple stomach chambers (such as four chambers in cows). This allows them to ferment and break down tough plant fibers like cellulose before further digestion. Non‐ruminant herbivores, like horses, have a single‐chambered stomach similar to humans but rely on their larger caecum and large intestine to ferment and break down plant fiber after it passes through the stomach. 3. How do the digestive systems of ruminant and non‐ruminant herbivores influence their eating patterns? Ruminant herbivores, like cows, can graze and eat larger meals less frequently because they ferment food in their multi‐chambered stomachs before further digestion. Non‐ruminant herbivores, like horses, need to eat smaller amounts of food throughout the day to maintain a continuous flow of nutrients, as their digestion process takes place mainly in the cecum and colon after food leaves the stomach. 4. Summarise the differences between the digestive system of humans and ruminant herbivores, such as a cow. Humans have a single‐chambered stomach and a relatively short digestive tract suited for processing a variety of foods. In contrast, ruminant herbivores like cows have multiple stomach chambers (four in cows) for fermenting tough plant material like cellulose. While humans rely on enzymes to break down food directly, cows ferment their food before further digestion, requiring a much longer and more complex digestive system. 5. Summarise the differences between the digestive system of humans and non‐ruminant herbivores, such as a horse. Humans and non‐ruminant herbivores like horses both have single‐chambered stomachs, but horses have a longer caecum and large intestine, which are critical for fermenting and breaking down plant fibre. Humans, with a shorter digestive tract, process food more directly, while horses rely on fermentation after food leaves the stomach, allowing them to digest fibrous plant material more slowly over time. 6. Why do carnivores, such as lions, have a shorter digestive tract compared to herbivores? Carnivores like lions have a shorter digestive tract because meat is easier to digest than plant material. They don’t need to break down tough fibre, so their digestive system is more streamlined. Their highly acidic stomachs and powerful enzymes help quickly digest the proteins in meat, reducing the need for a long digestive tract. 7. Compare the digestive system of a human to a carnivore, such as a lion. Both humans and carnivores like lions have relatively short digestive tracts compared to herbivores. However, lions have a more acidic stomach and powerful enzymes specifically adapted to break down meat proteins, while humans have a more balanced digestive system suited for both plant and animal‐based foods. Humans have enzymes for digesting carbohydrates, fats, and proteins, whereas lions don’t need to process plant fibre, so their stomachs are optimized for meat digestion. Across the whole planet, humans eat on average between 1 and 2.7 kilograms of food a day. That's over 365 kilograms a year per person, and more than 28,800 kilograms over the course of a lifetime. And every last scrap makes its way through the digestive system. Comprised of 10 organs, covering 9 meters, and containing over 20 specialized cell types, this is one of the most diverse complicated systems in the human body. Its parts continuously work in unison to fulfill a singular task, transforming the raw materials of your food into the nutrients and energy that keep you alive. Spanning the entire length of your torso, the digestive system has four main components. First, there's the gastrointestinal tract, a twisting channel that transports your food and has an internal surface area of between 30 and 40 square meters. enough to cover half a badminton court. Second, there's the pancreas, gallbladder, and liver, a trio of organs that break down food using an array of special juices. Third, the body's enzymes, hormones, nerves, and blood all work together to break down food, modulate the digestive process, and deliver its final products. Finally, there's the mesentery, a large stretch of tissue that supports and positions all your digestive organs in the abdomen. enabling them to do their jobs. The digestive process begins before food even hits your tongue. Anticipating a tasty morsel, glands in your mouth start to pump out saliva. We produce about 1.5 liters of this liquid each day. Once inside your mouth, chewing combines with the sloshing saliva to turn food into a moist lump called the bolus. Enzymes present in the saliva break down any starch, Then your food finds itself at the rim of a 25-centimeter-long tube called the esophagus, down which it must plunge to reach the stomach. Nerves in the surrounding esophageal tissue sense the bolus's presence and trigger peristalsis, a series of defined muscular contractions. That propels the food into the stomach, where it's left at the mercy of the muscular stomach walls, which pound the bolus, breaking it into chunks. Hormones secreted by cells in the lining trigger the release of acids and enzyme-rich juices from the stomach wall that start to dissolve the food and break down its proteins. These hormones also alert the pancreas, liver, and gallbladder to produce digestive juices and transfer bile, a yellowish-green liquid that digests fat, in preparation for the next stage. After three hours inside the stomach, the once shapely bolus is now a frothy liquid called chyme, and it's ready to move into the small intestine. The liver sends bile to the gallbladder, which secretes it into the first portion of the small intestine, called the duodenum. Here, it dissolves the fats floating in the slurry of chyme so they can be easily digested by the pancreatic and intestinal juices that have leached onto the scene. for easier absorption into the body. The enzymes also carry out the final deconstruction of proteins into amino acids and carbohydrates into glucose. This happens in the small intestine's lower regions, the jejunum and ileum, which are coated in millions of tiny projections called villi. These create a huge surface area to maximize molecule absorption and transference into the bloodstream. The blood takes them on the final leg of their journey, to feed the body's organs and tissues. But it's not over quite yet. Leftover fiber, water, and dead cells sloughed off during digestion make it into the large intestine, also known as the colon. The body drains out most of the remaining fluid through the intestinal wall. What's left is a soft mass called stool. The colon squeezes this byproduct into a pouch called the rectum, where nerves sense it expanding, and tell the body when it's time to expel the waste. The byproducts of digestion exit through the anus, and the food's long journey, typically lasting between 30 and 40 hours, is finally complete. Go ahead and think for a moment about your very favorite food. What is it? Pizza? Macaroni and cheese? Chicken salad? Sushi? Well, we all have different food preferences, but food is a source of large molecules that are needed for life called biomolecules. There are four major biomolecules that make up all of life, and this will be the focus of this video. Before we get into details about the four biomolecules, we need to talk about one very important vocabulary word, the word monomer. A monomer is a building block. If I had some large substance, the parts that make up the substance are called monomers, just like building blocks. We're going to talk a lot about monomers today because we need to understand what the biomolecules are made of. And we need to understand biomolecules because they're building components of life. So let's introduce the four biomolecules now and talk a little bit about their functions. We'll start with carbohydrates, carbs. Well, carbs are something that you've probably heard a lot about when people are talking about diets. You know, they try to go low carb or maybe they want a lot of carbs. Diets always come and go. Pasta and breads are examples of foods heavy in carbohydrates. Carbs are actually a very important source of energy. In fact, that's one big function of carbs. They are a great, fast source of energy. If you are a marathon runner, you might want to eat a lot of carbs the night before a race. Lots of marathon runners do this. It's called pasta loading. They eat a big pasta dinner the night before they go out on their marathon. Now, carbs have a monomer. Again, remember, monomers are building blocks. The monomer for a carb is a monosaccharide. I know that's a big mouthful, but monosaccharides make up carbohydrates. Next one up is a diverse group known as lipids. Lipids are better known as fats, and they have two different types of building blocks. One type of building block is called a fatty acid, and the other type is called a glycerol. Now, examples of lipids include butter, oil, and cholesterol. Lipids, though, they have a lot of great functions. You might think, well, that's fat. How good can fat be? Well, it just depends when you put it into context. For example, you know those really adorable seals that you see on calendars? They have this fluffy white hair. They're actually called a harp seal. Well, they only look like that when they're babies. When they get older, they're not quite as cute. In their little baby stage, they actually have a lot of this hair that they're born with that keeps them warm. But over time, they have to develop blubber. It's fat, and it helps keep them warm. Lipids are great for insulating. Also, you might not think about fats as being related to energy, but fats are a great source of long-term energy. They can store energy for a long, long time. Say, for example, you wanted to swim the English Channel. That's like 21 miles of swimming. The fastest swimmers might be able to do that in 7 or 8 hours, but it might take a lot longer than that for the average swimmer. More like 25 hours, and that's a lot of swimming. Well, you would want to make sure that your body has enough lipids, enough stored fat, that it can pull upon. Because after you burn off those carbohydrates, remember, carbohydrates, carbs are the fast source of energy, you might not have enough energy storage unless you have some lipids on hand. Lipids also make up cell membranes, so they are very important for life because all living things are made of cells. Of course, an excessive amount of lipids could be a bad thing for your health. Remember, it's all about moderation. Okay, next, proteins. Now when you hear about proteins, a power bars. They say they have a lot of protein in them and that they help with muscle building. Well, protein is great for muscle building. Examples of foods that are high in protein include meats and many types of beans. The monomers of protein are amino acids. So sometimes you see these labels that say, this has 20 amino acids in this food. And really, they're just trying to say that it has protein. Because proteins are made of amino acids, so... That's just some fancy advertising for you. But in addition to being important for muscle development, protein is also very important for other functions, such as working in the immune system and acting as enzymes. Remember, enzymes are made of proteins, so proteins are important for the body. Now, when we start talking about genes, the DNA genes, not the genes you wear, the DNA codes for proteins that are very important for structure and function in the body. The last biomolecule is known as a nucleic acid. Nucleic acids include DNA and RNA, which we'll get to when we get to genetics. They have a monomer called a nucleotide. That's going to be an easy one for you to remember because nucleotide sounds a lot like nucleic acid. And if considering DNA and RNA, both of these are involved in genetic information for the coding of your traits. They are found in a lot of your food because Whenever you eat something that came from something once living, it can still contain the DNA. For example, when you eat a strawberry, you're actually consuming all the cells that make up that strawberry. And in the nucleus of all those strawberry cells is DNA. Plants and animals both have DNA. In fact, any type of life must contain nucleic acids to direct the cell's activities. So we just powered through introducing the four biomolecules by providing examples, exploring their monomers, and giving some general functions. One last very important part to mention is the structure of these biomolecules. Understanding the structure can help with predicting their properties and easily being able to identify them. One thing I like to tell students to do is to write the four biomolecules in the same order that we went through. Carbs, lipids, proteins, and nucleic acids. Then remember this mnemonic device that goes with these four biomolecules. Cho-cho-chan-chomp. Instead of chomp at the end with an M, it's chomp at the end with an N. The C stands for carbon, the H stands for hydrogen, the O for oxygen, so Carbs, lipids, proteins, and nucleic acids all have that CHO in there. It's just that proteins and nucleic acids also have an N, which is nitrogen. And nucleic acids additionally have a P, which is for phosphorus. So again, CHO, CHO, CHON, CHOMP, the major elements in the four biomolecules. Now, these elements are arranged differently in the four biomolecules. It's important to explore the arrangement of the elements in biomolecules because the structure of that arrangement greatly impacts the biomolecule function. So, to the Google to discover some biomolecule arrangement illustrations. Well, that's it for the amoeba sisters, and we remind you to stay curious. Welcome to MooMooMath and Science. In this video I would like to take a look at the movement of food through the digestive system and the enzymes along the way. Enzymes are essential for digestion because they help speed up chemical reactions. One way an enzyme speeds up a chemical reaction is by reducing the amount of energy needed to start the reaction. As food moves along the digestive system enzymes are added along the way. In the mouth or oral cavity salivary glands help start digestion. Lipase is secreted and this helps break down lipids. And amylase is secreted and this helps to break down carbohydrates. From the mouth the food travels down the esophagus and into the stomach. In the stomach several enzymes are secreted. Pepsin is the main enzyme in the stomach. Pepsin breaks down the protein in the food into small particles. Protein digestion therefore starts in the stomach and carbohydrates and lipids start their digestion in the mouth. As food exits the stomach it enters the first portion of the small intestine called the duodenum. The pancreatic duct is located here and releases enzymes produced by the pancreas. This pancreatic juice is a combination of at least 7 different enzymes. This pancreatic juice breaks down proteins, glycogen and starch. Finally as food travels into the small intestine additional enzymes are added. Enzymes whose function is to further break down the chyme released from the stomach. You will find the following enzymes in the small intestine. Lactase is a significant enzyme that breaks down lactose that is found in many dairy products. If you are lactose intolerant you either lack this enzyme or have a reduced amount. So there we go the flow of food and enzymes that help you break down and digest your food. Thanks for watching and MooMooMath uploads a new math and science video every day. Please subscribe and share. And with her new teeth, she can take on more solid foods. Digestion starts in the mouth. Teeth grind up the food. Then, special glands under the tongue pump out saliva to help break down and lubricate the food on its 12-hour, 13-foot journey through the gut. It'll pass from the stomach into the coils of the small intestine before finally passing into the large intestine. Waves of contracting muscle keep the food moving, a process called peristalsis. These contractions are so powerful, we can even eat upside down. For the first time, a new camera shows a high definition view of how food travels through our bodies and into our stomachs. Food enters the stomach through a hole at the top. The stomach is a bag of muscle that churns, squashes and squeezes food into liquid. At the same time acids break the food down. The stomach walls protect themselves with a lining of mucus. Without it, the acids could digest parts of the stomach itself, causing stomach ulcers. About an hour later, the stomach squeezes the broken-down food out through a tiny hole called the pyloric sphincter. The food enters the small intestine, an 11-foot coil of tube where we absorb most of the nutrients. The interior wall of the small intestine is lined with millions of microscopic projections called Vili. These increase the surface area of the gut, making it easier to absorb nutrients. First, the pancreas pumps out a juice that neutralizes stomach acid. Then bile from the liver breaks down the fats into tiny droplets. Smaller droplets are easier for the intestine to absorb. After an hour and a half, the small intestine has absorbed most of the nutrients from the food. It's time for what remains to move on. It enters the large intestine through this, the ileocecal sphincter, a valve that keeps our food from going back where it came from. What's left is a mix of waste food and dead cells from the walls of the gut. The large intestines main job is to extract water from it. Lots of bacteria live here too. But it isn't because of an infection. We actually need them. They produce enzymes that break down complex carbohydrates in our food. Carbohydrates we couldn't otherwise digest. Finally, after about 12 hours, we expel what's left of our first meal. Year 8 Digestion Test 2023 - Solutions Multiple Choice Section 1. C – Peristalsis 2. B – Stomach 3. B – Bolus 4. D 5. C 6. A – Decrease fat digestion 7. B – 90mg/ml Short Answer Section 8. F T T T 9. a. Breaking down/digesting the food we eat (owtte) b. Glucose/ Simple sugar c. Mono-saccharide d. Has drawn at least 3 single hexagons 10. a. Iodine b. Any answer denoting a colour change to dark blue/black c. Benedict’s d. Reference to adding sample, water and Benedict’s to a test tube [1 mark] Method of heating the sample [1 mark] Reference to colour change to orange/red (reference to original blue colour not needed) [1 mark] 11. Correct labels for: [4 marks: 0.5 marks each] 12. a. Digestion of protein b. pH 7 (allow between 6.75-7.25) c. Identification of basic/alkaline environment [1 mark] Reference to optimum pH of trypsin being 9-9.5 [1 mark] 13. Credit any correct responses which may not be listed below in the table. Half a mark each for 2 sources in final column. Website with information on all vitamins (scroll down): https://www.medicalnewstoday.com/articles/195878#supplements Vitamin [1 mark] What it does [1 mark] Where we get it [1 mark] A Healthy eyesight Healthy skin Fresh vegetables Eggs B group Obtaining energy from foods Growth Formation of RBCs Making DNA/RNA Maintaining the nervous system Dairy Fish Meat Eggs Fortified cereals Leafy vegetables C Immunity Wound healing Bone formation Citrus fruits Fresh fruit Fresh vegetables Body Systems: Digestion Year 8 Science Learning Intention Explain that multicellular organisms contain systems of organs that carry out specialised functions that enable them to survive (and reproduce). Body Systems • In multicellular organisms, body systems work together to maintain homeostasis and support the organism’s survival by performing specialised functions. • These systems are interdependent, ensuring the organism can grow, reproduce, and adapt to its environment. • Each system has a specific role such as: • Delivering oxygen (respiratory system) • Transporting nutrients & waste (circulatory system) • Breaking down food for energy (digestive system) • Coordinating responses (nervous system) Cell: The smallest unit of life Tissue: Group of cells similar in structure that perform a specific function. Organ: Structures made up of different types of tissue that perform specific functions. Body/Organ System: Groups of organs within our bodies that carry out specific functions. Working Together? Organs (Working Together) • A collection of organs will work together to achieve a purpose such as: • Enabling digestion • Transmitting blood and oxygen around the body • To remove wastes from the body • To send messages around the body • To assist with movement and structural support • When a set of organs work together, they make up a body system. Body Systems Digestive System: Collection of organs that help to break down food so that it can be absorbed by the body. Respiratory System: Helps to bring in oxygen and remove carbon dioxide. Circulatory System: Delivery system which carries oxygen and nutrients around the body via blood. Excretory System: Removes waste products from the body. Nervous System: Sends and receives messages throughout the body. Reproductive System: Enables to production of offspring. Musculoskeletal System: Includes the muscles and the skeleton which helps to move and support the body. Learning Intention Explain that the digestive system is one of those body systems that enable survival, and define the purposes of ingestion, digestion and egestion. What is Digestion? • Digestion involves a series of processes that break down the food you consume so that the nutrients are small enough to be absorbed into your blood. • Key Terms: Ingestion Process of taking food and drink into the body through the mouth. Egestion Process of expelling undigested and unabsorbed food material from the digestive system as waste. Digestive Processes • This involves five processes before egestion occurs: • ingestion • mechanical digestion • chemical digestion • absorption • assimilation Ingestion: Consuming food Mechanical Digestion: Physically breaking down food into smaller pieces using your teeth. Chemical Digestion: Enzymes will assist in helping to break down food into smaller pieces. Absorption: Small finger shaped structures lining the small intestine known as villi take in (absorb) the nutrients from the food you consumed. Assimilation: The nutrients from the food are converted into chemicals in your cells so they can be used by the body as energy. Learning Intention Compare and contrast, with specific examples, mechanical and chemical digestion. Digestion: Mechanical and Chemical Aspect Mechanical Digestion Chemical Digestion Definition Physical breakdown of food into small pieces. Chemical breakdown of food into smaller pieces. Processes Involves physical actions such as chewing, churning and grinding. Involves enzymes and chemical reactions. Primary Function Prepares food for chemical digestions by increasing surface area. Converts food into absorbable molecules like amino acids, glucose and fatty acids. Location Mouth, stomach, and intestines. Mouth, stomach and small intestines. Involvement of Does not involved enzymes. Enzymes (catalysts that speed up chemical reactions) Involves enzymes like amylase, lipase and pepsin. Examples Saliva (contains enzyme amylase that breaks down carbohydrates). Chewing Food needs to be broken down so that the nutrients can be absorbed into the bloodstream. Mechanical Digestion (Physical Digestion) • Food is taken in through the mouth and broken down using your teeth. • Using our teeth allows us to: • Bite • Tear • Crush • Grind • Once the teeth physically break down the food into smaller pieces, the tongue rolls the food until it is in a ball like shape. • This ball like collection of food is known as a ‘bolus’. Chemical Digestion • Chemical digestion occurs due to enzymes which help to break down the foods using a chemical process. • Enzymes are proteins that act as biological catalysts, meaning they speed up reactions without being used up. • Enzymes are used in the digestive system to break large, complex, insoluble food molecules into small, simple, soluble molecules so they can be absorbed into the bloodstream. • Different types of enzymes can break down different nutrients. Learning Intention Explain the importance of food as a source of energy, for providing building blocks for growth and repair, and chemicals for regulation and control. Describe the nature of carbohydrates, lipids (fats & oils), and proteins, including their basic chemical structure, roles they play in the body, and food sources. What are Nutrients? • Nutrients are substances that living organisms need to survive, grow, and function properly. • They are characterized into six main groups: • Carbohydrates • Proteins • Fats • Vitamins • Minerals • Water The digestive system helps to break down food so that the nutrients can be absorbed in a form that can be used by the body. Carbohydrates • Provide the body with energy. • Found in food sources such as bread, rice, fruits and vegetables. Simple Carbohydrates Complex Carbohydrates Made of one or two sugar units. Made of many sugar units linked together. Quickly broken down into glucose, leading to a rapid spike in blood sugar. Broken down more slowly into glucose, providing steady energy release. Found in sugary foods such as fruits, lollies and soft drinks. Found in whole grains, vegetables and legumes. Example: Glucose (monosaccharide) & sucrose (disaccharide) Example: Starch (polysaccharide) Types of Carbohydrates Monosaccharide Disaccharide Polysaccharide Single sugar unit Two sugar units joined Many sugar units joined together Glucose Fructose Examples of foods? Sucrose Starch Examples of foods? Take less time to digest Take longer to digest Protein • Required for the body to build and repair tissues, like muscles, skin and organs. • Essential for growth and healing. • Made of smaller building blocks called amino acids. • Found in food sources such as: • Meat • Eggs • Beans • Nuts Fats • Provide energy and help the body to absorb nutrients. • Made of molecules called triglycerides. • Essential for protecting organs and storing energy. • Fats are found in food sources such as: • Oils • Butter • Nuts • Fatty fish Vitamins & Minerals • Vitamins & minerals are vital for immune system functioning and body development. • Vitamins are made by plants and animals. • Examples include: • Vitamin A • Vitamin C • Vitamin B group • Minerals are inorganic elements that are found in soil & water – which are then ingested by animals or absorbed by plants. • Examples include: • Calcium • Iron • Potassium VITAMIN A (Fat Soluble) What we need it for: Food Sources: • Immune system functioning • Healthy eye sight • Skin (vitamin A is also known as retinol) • • • • • • Signs of Deficiency: Carrots • Night blindness Dark green vegetables • Dry skin Fish Eggs Dairy Liver Too much: • • • • Blurred vision Headaches Organ damage Skin conditions VITAMIN C (Water Soluble) What we need it for: Food Sources: • Immunity • Maintaining healthy skin • Wound healing • • • • Citrus fruits Strawberries Broccoli Brussel Sprouts Signs of Deficiency: Too much: • Scurvy (weakness, • Diarrhea anemia, gum disease) VITAMIN B Group (Water Soluble) Group of Vitamins that includes (amongst others): • Thiamin (B1) • Riboflavin (B2) • Folate (B9) What we need it for: Food Sources: • Obtaining energy from • Meat food. • Fish • Dairy • Vegetables • Nuts Signs of Deficiency: Too much: • Lack of energy • Nausea • Diarrhea CALCIUM What we need it for: Food Sources: Signs of Deficiency: Too much: • Healthy bones and teeth • Blood clotting • Muscles contraction & relaxation • Dairy products • Leafy green vegetables • Osteoporosis (long term) • Weak nails • Hair breakage • Fatigue • Kidney stones IRON What we need it for: Food Sources: Signs of Deficiency: Too much: • Makes haemoglobin (part of red blood cells that transports oxygen to cells) • Red meat • Green leafy vegetables • Eggs • Chicken • Fish • Anemia • Stomach ulcers POTASSIUM What we need it for: Food Sources: • Maintains body fluids • Muscle contractions • Nerve signals • • • • Bananas Sweet potatoes Oranges Green leafy vegetables Signs of Deficiency: Too much: • Muscle weakness • Muscle cramps • Fatigue • Heart palpitations • Shortness of breath Learning Intention Explain what happens to carbohydrates, proteins and lipids (fats and oils) during digestion. Explain the roles of various digestive enzymes. Breaking Down Carbohydrates Breaking Down Protein Breaking Down Fats Learning Intention Identify and label each organ in the digestive system and relate their function to the overall role in the digestive system. Relate to the conditions under which various digestive enzymes operate within the organs of the digestive system. Processes of Digestion Mouth (To the Oesophagus) • Teeth: Involved in the mechanical breakdown of food into smaller pieces. • This will assist with chemical digestion. • Saliva: Enzyme in salvia called ‘amylase’ secreted. • Breaks down carbohydrates • Tongue: Rolls food into a ball known as ‘bolus’. Oesophagus (To the Stomach) • The bolus is sent down the oesophagus through a process called ‘peristalsis’. • Peristalsis involves muscle contractions which help to push the bolus down towards the stomach. Stomach (To the small intestine) • The stomach is an organ that also plays a role in mechanical and chemical digestion. • Mechanical Digestion: The stomach churns which helps to mix up the food with the gastric juice that is contained in the stomach. • Chemical Digestion: The gastric juice starts to break down the proteins within the stomach. • The stomach can store the contents until it is ready to go through the next process in digestion. • This can take from 2 to 6 hours (depending on the source). • Pepsin is secreted (activated by the acidic nature of the gastric juices) to begin breakdown of protein. Chyme: Semi-liquid mixture of partially digested food. Created in the stomach when churning occurs. Small Intestine (To the Large Intestine) • Named the ‘small’ intestine due to the narrow width. • The small intestine is about 6 metres in length. • There are three sections. • Food travels through the small intestine through the process of peristalsis. • This is where the nutrients are absorbed. • Small finger-like structures called ‘villi’ line the small intestine and absorb the nutrients into the blood stream. Small Intestine • Mechanical Digestion: • Segmentation: Contractions of the small intestine wall that continues to mix chyme with digestive enzymes and bile, increasing contact with the lining of the intestine wall. • Bile is secreted (breaks down fats and oils – no chemical reaction/new substance created) • Chemical Digestion: • Enzymes are secreted: • Amylase (breaks down carbohydrates) • Lipase (breaks down fats) • Pepsin (breaks down protein) Small Intestine Segments Duodenum Around 25cm • Site where chemical digestion begins in the intestine. • Receives chyme from the stomach. • Mixes with bile from the liver and gall bladder to emulsify fats. • Mixes with digestive enzymes from the pancreas (neutralises stomach acids). Jejunum Around 2.5m • Primarily responsible for absorbing nutrients such as carbohydrates (glucose), proteins (as amino acids) and vitamins & minerals. • Contains dense villi and microvilli. Ileum Around 3.5m • Absorbs remaining nutrients Large Intestine (To the Rectum & Anus) • The large intestine gets its name from the width which is greater than that of the small intestine. • It is about 1.5 metres in length. • Most of the nutrients have already been absorbed by the time it reaches the large intestine, but some vitamins can still be found. • It absorbs water from the substance, resulting in a firmer product. • The large intestine transmits this now waste product from the food out of the body. Rectum & Anus • The rectum stores the remaining faecal matter as it waits to be removed from the body. • When the rectum starts to stretch to accommodate the waste product, a signal is sent to the brain which is interpreted as a need to go to the bathroom. • The anus is a ring of muscle which will remain closed when not needed. • When removing waste, the anus will stretch open to allow the waste product to exit the body. Additional Components of Digestion Liver & Gall Bladder • Both assist in the break down of fats and oils within food. • The liver produces a green substance known as ‘bile’ which breaks down the fats and oils. • The gall bladder stores the bile for when the food reaches the small intestine. Pancreas • Makes ‘pancreatic juice’. • This juice assists in helping to neutralise stomach acid. • The pancreas also creates enzymes which are used to chemically break down food. 1. Food is ingested through the mouth. Chemical Digestion: Break down of food through enzyme in saliva. Mechanical Digestion: Break down of food through teeth (tongue then rolls food into ball called ‘bolus’). 2. Bolus is then pushed down oesophagus through a process known as peristalsis. 3. Bolus enters the stomach. Chemical Digestion: Acids in the stomach further break down the food. Mechanical Digestion: The stomach churns the food. 4. Food enters the small intestine which is lined with finger like structures known as ‘villi’ which absorb the nutrients. 5. The remaining mass then passes through the large intestine where the remaining nutrients and the water are absorbed. 6. The waste is stored in the rectum and when full, will send a signal to be released via the anus (egestion). Digestive Explosions Burping When a build up of gas is released from the mouth. Occurs when air is taken in too quickly (through talking whilst eating, eating/drinking too quickly). Heartburn Burning sensation in the chest that occurs when stomach acid rises up into the oesophagus Flatulence The passing of wind. Due to gases that build up in the large intestine which are created by the presence of bacteria. Diarrhoea When undigested food moves too quickly through the small and then large intestine. Due to presence of bacteria, villi can swell, therefore not absorbing nutrients. The large intestine then passes the substance through too fast to absorb any water, resulting in the expulsion of watery faeces. Vomiting When stomach contents is forcefully ejected out of the stomach, up the oesophagus and through the mouth.  D Bone health Immunity Sunlight Fish Eggs Liver 14. A bar graph shown like: with 1 mark for x-axis label, 1 mark for bars and 1 mark for y axis scaling Distance along the small intestine (cm) b) Villi create a larger surface area [1 mark] Reference to this increasing the rate of digestion/absorption of food into the blood [1 mark] c) 1 mark describing the data The concentration of glucose increases from 50 – 500 from 100cm distance through to 300cm distance along the small intestine and drops from 500 (to 250 after 500cm) back down to 0 at 700cm. Units? Mol/dm-3 not sure if needed at Yr 8 level, but some reference point of numbers needed 1 mark for stating that the concentration of glucose increases due to carbohydrates broken down / digested into sugars (glucose) And 1 mark for stating the reduction in glucose is where the glucose would then be absorbed into blood stream Body Systems: Digestion Year 8 Science Learning Intention Explain that multicellular organisms contain systems of organs that carry out specialised functions that enable them to survive (and reproduce). Body Systems • In multicellular organisms, body systems work together to maintain homeostasis and support the organism’s survival by performing specialised functions. • These systems are interdependent, ensuring the organism can grow, reproduce, and adapt to its environment. • Each system has a specific role such as: • Delivering oxygen (respiratory system) • Transporting nutrients & waste (circulatory system) • Breaking down food for energy (digestive system) • Coordinating responses (nervous system) Cell: The smallest unit of life Tissue: Group of cells similar in structure that perform a specific function. Organ: Structures made up of different types of tissue that perform specific functions. Body/Organ System: Groups of organs within our bodies that carry out specific functions. Working Together? Organs (Working Together) • A collection of organs will work together to achieve a purpose such as: • Enabling digestion • Transmitting blood and oxygen around the body • To remove wastes from the body • To send messages around the body • To assist with movement and structural support • When a set of organs work together, they make up a body system. Body Systems Digestive System: Collection of organs that help to break down food so that it can be absorbed by the body. Respiratory System: Helps to bring in oxygen and remove carbon dioxide. Circulatory System: Delivery system which carries oxygen and nutrients around the body via blood. Excretory System: Removes waste products from the body. Nervous System: Sends and receives messages throughout the body. Reproductive System: Enables to production of offspring. Musculoskeletal System: Includes the muscles and the skeleton which helps to move and support the body. Learning Intention Explain that the digestive system is one of those body systems that enable survival, and define the purposes of ingestion, digestion and egestion. What is Digestion? • Digestion involves a series of processes that break down the food you consume so that the nutrients are small enough to be absorbed into your blood. • Key Terms: Ingestion Process of taking food and drink into the body through the mouth. Egestion Process of expelling undigested and unabsorbed food material from the digestive system as waste. Digestive Processes • This involves five processes before egestion occurs: • ingestion • mechanical digestion • chemical digestion • absorption • assimilation Ingestion: Consuming food Mechanical Digestion: Physically breaking down food into smaller pieces using your teeth. Chemical Digestion: Enzymes will assist in helping to break down food into smaller pieces. Absorption: Small finger shaped structures lining the small intestine known as villi take in (absorb) the nutrients from the food you consumed. Assimilation: The nutrients from the food are converted into chemicals in your cells so they can be used by the body as energy. Learning Intention Compare and contrast, with specific examples, mechanical and chemical digestion. Digestion: Mechanical and Chemical Aspect Mechanical Digestion Chemical Digestion Definition Physical breakdown of food into small pieces. Chemical breakdown of food into smaller pieces. Processes Involves physical actions such as chewing, churning and grinding. Involves enzymes and chemical reactions. Primary Function Prepares food for chemical digestions by increasing surface area. Converts food into absorbable molecules like amino acids, glucose and fatty acids. Location Mouth, stomach, and intestines. Mouth, stomach and small intestines. Involvement of Does not involved enzymes. Enzymes (catalysts that speed up chemical reactions) Involves enzymes like amylase, lipase and pepsin. Examples Saliva (contains enzyme amylase that breaks down carbohydrates). Chewing Food needs to be broken down so that the nutrients can be absorbed into the bloodstream. Mechanical Digestion (Physical Digestion) • Food is taken in through the mouth and broken down using your teeth. • Using our teeth allows us to: • Bite • Tear • Crush • Grind • Once the teeth physically break down the food into smaller pieces, the tongue rolls the food until it is in a ball like shape. • This ball like collection of food is known as a ‘bolus’. Chemical Digestion • Chemical digestion occurs due to enzymes which help to break down the foods using a chemical process. • Enzymes are proteins that act as biological catalysts, meaning they speed up reactions without being used up. • Enzymes are used in the digestive system to break large, complex, insoluble food molecules into small, simple, soluble molecules so they can be absorbed into the bloodstream. • Different types of enzymes can break down different nutrients. Learning Intention Explain the importance of food as a source of energy, for providing building blocks for growth and repair, and chemicals for regulation and control. Describe the nature of carbohydrates, lipids (fats & oils), and proteins, including their basic chemical structure, roles they play in the body, and food sources. What are Nutrients? • Nutrients are substances that living organisms need to survive, grow, and function properly. • They are characterized into six main groups: • Carbohydrates • Proteins • Fats • Vitamins • Minerals • Water The digestive system helps to break down food so that the nutrients can be absorbed in a form that can be used by the body. Carbohydrates • Provide the body with energy. • Found in food sources such as bread, rice, fruits and vegetables. Simple Carbohydrates Complex Carbohydrates Made of one or two sugar units. Made of many sugar units linked together. Quickly broken down into glucose, leading to a rapid spike in blood sugar. Broken down more slowly into glucose, providing steady energy release. Found in sugary foods such as fruits, lollies and soft drinks. Found in whole grains, vegetables and legumes. Example: Glucose (monosaccharide) & sucrose (disaccharide) Example: Starch (polysaccharide) Types of Carbohydrates Monosaccharide Disaccharide Polysaccharide Single sugar unit Two sugar units joined Many sugar units joined together Glucose Fructose Examples of foods? Sucrose Starch Examples of foods? Take less time to digest Take longer to digest Protein • Required for the body to build and repair tissues, like muscles, skin and organs. • Essential for growth and healing. • Made of smaller building blocks called amino acids. • Found in food sources such as: • Meat • Eggs • Beans • Nuts Fats • Provide energy and help the body to absorb nutrients. • Made of molecules called triglycerides. • Essential for protecting organs and storing energy. • Fats are found in food sources such as: • Oils • Butter • Nuts • Fatty fish Vitamins & Minerals • Vitamins & minerals are vital for immune system functioning and body development. • Vitamins are made by plants and animals. • Examples include: • Vitamin A • Vitamin C • Vitamin B group • Minerals are inorganic elements that are found in soil & water – which are then ingested by animals or absorbed by plants. • Examples include: • Calcium • Iron • Potassium VITAMIN A (Fat Soluble) What we need it for: Food Sources: • Immune system functioning • Healthy eye sight • Skin (vitamin A is also known as retinol) • • • • • • Signs of Deficiency: Carrots • Night blindness Dark green vegetables • Dry skin Fish Eggs Dairy Liver Too much: • • • • Blurred vision Headaches Organ damage Skin conditions VITAMIN C (Water Soluble) What we need it for: Food Sources: • Immunity • Maintaining healthy skin • Wound healing • • • • Citrus fruits Strawberries Broccoli Brussel Sprouts Signs of Deficiency: Too much: • Scurvy (weakness, • Diarrhea anemia, gum disease) VITAMIN B Group (Water Soluble) Group of Vitamins that includes (amongst others): • Thiamin (B1) • Riboflavin (B2) • Folate (B9) What we need it for: Food Sources: • Obtaining energy from • Meat food. • Fish • Dairy • Vegetables • Nuts Signs of Deficiency: Too much: • Lack of energy • Nausea • Diarrhea CALCIUM What we need it for: Food Sources: Signs of Deficiency: Too much: • Healthy bones and teeth • Blood clotting • Muscles contraction & relaxation • Dairy products • Leafy green vegetables • Osteoporosis (long term) • Weak nails • Hair breakage • Fatigue • Kidney stones IRON What we need it for: Food Sources: Signs of Deficiency: Too much: • Makes haemoglobin (part of red blood cells that transports oxygen to cells) • Red meat • Green leafy vegetables • Eggs • Chicken • Fish • Anemia • Stomach ulcers POTASSIUM What we need it for: Food Sources: • Maintains body fluids • Muscle contractions • Nerve signals • • • • Bananas Sweet potatoes Oranges Green leafy vegetables Signs of Deficiency: Too much: • Muscle weakness • Muscle cramps • Fatigue • Heart palpitations • Shortness of breath Learning Intention Explain what happens to carbohydrates, proteins and lipids (fats and oils) during digestion. Explain the roles of various digestive enzymes. Breaking Down Carbohydrates Breaking Down Protein Breaking Down Fats Learning Intention Identify and label each organ in the digestive system and relate their function to the overall role in the digestive system. Relate to the conditions under which various digestive enzymes operate within the organs of the digestive system. Processes of Digestion Mouth (To the Oesophagus) • Teeth: Involved in the mechanical breakdown of food into smaller pieces. • This will assist with chemical digestion. • Saliva: Enzyme in salvia called ‘amylase’ secreted. • Breaks down carbohydrates • Tongue: Rolls food into a ball known as ‘bolus’. Oesophagus (To the Stomach) • The bolus is sent down the oesophagus through a process called ‘peristalsis’. • Peristalsis involves muscle contractions which help to push the bolus down towards the stomach. Stomach (To the small intestine) • The stomach is an organ that also plays a role in mechanical and chemical digestion. • Mechanical Digestion: The stomach churns which helps to mix up the food with the gastric juice that is contained in the stomach. • Chemical Digestion: The gastric juice starts to break down the proteins within the stomach. • The stomach can store the contents until it is ready to go through the next process in digestion. • This can take from 2 to 6 hours (depending on the source). • Pepsin is secreted (activated by the acidic nature of the gastric juices) to begin breakdown of protein. Chyme: Semi-liquid mixture of partially digested food. Created in the stomach when churning occurs. Small Intestine (To the Large Intestine) • Named the ‘small’ intestine due to the narrow width. • The small intestine is about 6 metres in length. • There are three sections. • Food travels through the small intestine through the process of peristalsis. • This is where the nutrients are absorbed. • Small finger-like structures called ‘villi’ line the small intestine and absorb the nutrients into the blood stream. Small Intestine • Mechanical Digestion: • Segmentation: Contractions of the small intestine wall that continues to mix chyme with digestive enzymes and bile, increasing contact with the lining of the intestine wall. • Bile is secreted (breaks down fats and oils – no chemical reaction/new substance created) • Chemical Digestion: • Enzymes are secreted: • Amylase (breaks down carbohydrates) • Lipase (breaks down fats) • Pepsin (breaks down protein) Small Intestine Segments Duodenum Around 25cm • Site where chemical digestion begins in the intestine. • Receives chyme from the stomach. • Mixes with bile from the liver and gall bladder to emulsify fats. • Mixes with digestive enzymes from the pancreas (neutralises stomach acids). Jejunum Around 2.5m • Primarily responsible for absorbing nutrients such as carbohydrates (glucose), proteins (as amino acids) and vitamins & minerals. • Contains dense villi and microvilli. Ileum Around 3.5m • Absorbs remaining nutrients Large Intestine (To the Rectum & Anus) • The large intestine gets its name from the width which is greater than that of the small intestine. • It is about 1.5 metres in length. • Most of the nutrients have already been absorbed by the time it reaches the large intestine, but some vitamins can still be found. • It absorbs water from the substance, resulting in a firmer product. • The large intestine transmits this now waste product from the food out of the body. Rectum & Anus • The rectum stores the remaining faecal matter as it waits to be removed from the body. • When the rectum starts to stretch to accommodate the waste product, a signal is sent to the brain which is interpreted as a need to go to the bathroom. • The anus is a ring of muscle which will remain closed when not needed. • When removing waste, the anus will stretch open to allow the waste product to exit the body. Additional Components of Digestion Liver & Gall Bladder • Both assist in the break down of fats and oils within food. • The liver produces a green substance known as ‘bile’ which breaks down the fats and oils. • The gall bladder stores the bile for when the food reaches the small intestine. Pancreas • Makes ‘pancreatic juice’. • This juice assists in helping to neutralise stomach acid. • The pancreas also creates enzymes which are used to chemically break down food. 1. Food is ingested through the mouth. Chemical Digestion: Break down of food through enzyme in saliva. Mechanical Digestion: Break down of food through teeth (tongue then rolls food into ball called ‘bolus’). 2. Bolus is then pushed down oesophagus through a process known as peristalsis. 3. Bolus enters the stomach. Chemical Digestion: Acids in the stomach further break down the food. Mechanical Digestion: The stomach churns the food. 4. Food enters the small intestine which is lined with finger like structures known as ‘villi’ which absorb the nutrients. 5. The remaining mass then passes through the large intestine where the remaining nutrients and the water are absorbed. 6. The waste is stored in the rectum and when full, will send a signal to be released via the anus (egestion). Digestive Explosions Burping When a build up of gas is released from the mouth. Occurs when air is taken in too quickly (through talking whilst eating, eating/drinking too quickly). Heartburn Burning sensation in the chest that occurs when stomach acid rises up into the oesophagus Flatulence The passing of wind. Due to gases that build up in the large intestine which are created by the presence of bacteria. Diarrhoea When undigested food moves too quickly through the small and then large intestine. Due to presence of bacteria, villi can swell, therefore not absorbing nutrients. The large intestine then passes the substance through too fast to absorb any water, resulting in the expulsion of watery faeces. Vomiting When stomach contents is forcefully ejected out of the stomach, up the oesophagus and through the mouth. Using all this information, create the most detailed ever list of comprehensive notes and don't remove anything thats specific and important Okay, so I need to create really detailed notes on digestion for my Year 8 Science test. Let me start by looking through all the information provided. There's the Digestion Checklist Answers, Digestion Notes, a PowerPoint presentation, Practice Test Answers, some YouTube links, and additional explanations. I should organize this into sections based on the checklist objectives. First, the checklist mentions explaining multicellular organisms' systems. The digestive system's role is breaking down food and absorbing nutrients. Other systems like circulatory and respiratory assist by transporting oxygen and removing waste. I need to outline these clearly. Next, the objectives on ingestion, digestion, egestion. I have definitions for each. Also, comparing mechanical and chemical digestion. Chewing is mechanical, enzymes in the stomach are chemical. The mouth starts both processes with teeth and saliva. Types of teeth: incisors, canines, premolars, molars. Each has a function like cutting, tearing, grinding. Nutrients: carbohydrates, proteins, lipids, vitamins, minerals. Examples and their roles. Testing for each nutrient—Benedict's for sugars, iodine for starch, Biuret for proteins, Sudan III for fats. The experiments section also mentions graphing data, variables, and hypothesis vs. aim. Organs of the digestive system: mouth, esophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine, liver, gallbladder, pancreas. Functions of each, enzymes they secrete. Villi in the small intestine increase absorption area. Enzymes: amylase in saliva and pancreas breaks down carbs, pepsin in stomach for proteins, lipase from pancreas for fats. Bile from liver emulsifies fats. pH in stomach is 1.5-3.5, important for enzyme activation and killing bacteria. The large intestine absorbs water, forms feces. Appendix's role in immunity. Probiotics maintain gut microbiome. Digestive processes experiments: testing for nutrients, variables in experiments. Review questions cover definitions, matching teeth to functions, enzyme roles, effects of temperature on enzymes, pH importance, peristalsis, bile functions, villi structure, relationships between organs. Case studies on vitamin deficiencies, gut-brain axis, animal digestive systems comparisons. The research studies on probiotics and stress affecting gut health. Finally, detailed explanations of biomolecules: carbs, proteins, lipids, nucleic acids. Their monomers, functions, sources. I need to compile all this without missing specifics. Make sure to include each organ's role, enzymes, nutrient tests, processes like peristalsis, and diagrams if possible. Also, cover the experiments, variables, and case studies. Maybe structure it by checklist sections to follow the original document's flow. Year 8 Science: Digestion Comprehensive Notes (Based on Checklists, Notes, PPTs, and Test Answers) 1. Body Systems & Digestive System Overview Key Systems in Multicellular Organisms: Digestive System: Breaks down food, absorbs nutrients, removes waste. Circulatory System: Transports oxygen, nutrients, hormones; removes CO₂ (heart, blood vessels). Respiratory System: Exchanges oxygen and CO₂ (lungs, airways). Other Systems: Nervous, Excretory, Musculoskeletal, Reproductive. Digestive Processes: Ingestion: Taking in food through the mouth. Mechanical Digestion: Physical breakdown (e.g., chewing). Chemical Digestion: Enzymatic breakdown (e.g., amylase, pepsin). Absorption: Nutrients enter bloodstream (small intestine). Egestion: Elimination of undigested waste (faeces). Why Digestion is Essential for Survival: Provides energy (glucose), building blocks (amino acids), and removes harmful waste. Without digestion, nutrients cannot be absorbed, leading to starvation and toxin buildup. 2. Mechanical vs. Chemical Digestion Aspect Mechanical Digestion Chemical Digestion Definition Physical breakdown (no chemical change). Enzymatic breakdown into simpler molecules. Examples Chewing (teeth), stomach churning. Salivary amylase (mouth), pepsin (stomach). Key Organs Mouth, stomach. Mouth, stomach, small intestine. Mouth’s Role: Mechanical: Teeth (incisors cut, canines tear, premolars/molars grind). Chemical: Saliva (amylase breaks starch → maltose). Forms bolus. 3. Nutrients & Tests 5 Key Nutrients: Carbohydrates, Proteins, Fats, Vitamins, Minerals. Nutrient Function Food Sources Test Positive Result Carbohydrates Energy source. Bread, rice, pasta. Iodine (starch → blue-black). Color change to blue-black. Simple Sugars Quick energy. Fruits, honey. Benedict’s + heat (mono/disaccharides). Blue → orange/red. Proteins Growth/repair, enzymes, hormones. Meat, eggs, beans. Biuret solution. Blue → purple. Lipids Energy storage, cell structure. Avocados, nuts, oils. Sudan III (red layer) or brown paper (translucent). Red stain/transparency. Vitamins & Minerals: Vitamin A: Vision, skin (carrots, spinach). Vitamin C: Immunity, wound healing (oranges, capsicum). Vitamin D: Calcium absorption (fatty fish, sunlight). Calcium: Bones (dairy, leafy greens). Iron: Haemoglobin (red meat, beans). Potassium: Nerve/muscle function (bananas, potatoes). Probiotics: Beneficial gut bacteria aiding digestion, immunity, and mood regulation. 4. Digestive Enzymes & Organs Key Enzymes: Enzyme Source Substrate Products Optimal pH Amylase Salivary glands, Pancreas Starch (carbs) Maltose (sugar) Neutral (mouth), Alkaline (SI) Pepsin Stomach (from pepsinogen + HCl) Proteins Peptides Acidic (1.5–3.5) Lipase Pancreas Fats/Oils Fatty acids + glycerol Alkaline Organs & Functions: Mouth: Mechanical (teeth) + chemical (amylase) digestion. Stomach: Churns food; secretes HCl (pH 1.5–3.5) and pepsin. Produces chyme. Small Intestine: Duodenum: Bile (emulsifies fats) + pancreatic enzymes. Jejunum/Ileum: Nutrient absorption via villi/microvilli (↑ surface area). Pancreas: Secretes amylase, lipase, proteases, bicarbonate. Liver: Produces bile (stored in gallbladder). Large Intestine: Absorbs water; forms faeces (undigested fiber, bacteria). Villi Importance: Increase absorption area by ~600x (90% nutrient absorption). 5. Experiments & Key Skills Testing Methods: Starch: Iodine → blue-black. Glucose: Benedict’s + heat → orange/red. Proteins: Biuret → purple. Lipids: Sudan III (red layer) or brown paper (translucent). Graphing: Independent Variable (x-axis): Manipulated factor (e.g., enzyme concentration). Dependent Variable (y-axis): Measured outcome (e.g., reaction rate). Bar vs. Line Graphs: Compare categories vs. show trends over time. Aim vs. Hypothesis: Aim: Purpose of the experiment (e.g., "To test the effect of pH on enzymes"). Hypothesis: Predictive statement (e.g., "Enzymes work best at pH 7"). 6. Case Studies & Scenarios Vitamin/Mineral Deficiencies: Iron Deficiency: Fatigue, pale skin (anaemia). Vitamin C Deficiency: Bleeding gums, slow healing (scurvy). Calcium Deficiency: Weak bones (osteoporosis). Gut-Brain Axis: Connection: Gut microbiota produce serotonin (mood regulation). Stress Impact: Alters gut bacteria balance; probiotics improve mental health. Animal Digestive Systems: Herbivores: Longer intestines (e.g., cow’s 4-chambered stomach for cellulose). Carnivores: Shorter tract, acidic stomach (e.g., lion). Humans: Omnivores; balanced digestion of plants/meat. 7. Diagrams & Processes Peristalsis: Wave-like muscle contractions moving food through the GI tract. Chemical Structures: Carbohydrates: Monosaccharides (glucose), disaccharides (sucrose), polysaccharides (starch). Lipids: Triglycerides (glycerol + 3 fatty acids). Proteins: Amino acid chains. Digestion Flow: Mouth → Bolus → Oesophagus (peristalsis). Stomach → Chyme (HCl + pepsin). Small Intestine → Nutrient absorption (villi). Large Intestine → Water absorption → Faeces. 8. Common Mistakes & Tips Enzyme Sources: Amylase (mouth + pancreas), pepsin (stomach only). Disaccharide Test: Must hydrolyze to monosaccharides first (acid + heat). Villi Model vs. Reality: Real villi are 3D with thousands of microvilli. Key Mnemonics: CHO, CHO, CHON, CHOMP: Elements in biomolecules (Carbs, Lipids, Proteins, Nucleic Acids). Good Luck! Focus on enzyme roles, villi structure, nutrient tests, and organ functions. Use diagrams to visualize processes like peristalsis and chemical digestion. Objective: Explain that multicellular organisms contain systems of organs that carry out specialised functions that enable them to survive (and reproduce). Outline the role of the digestive system in the human body. The digestive system plays a crucial role in breaking down food and absorbing nutrients that the body needs to function. The digestive system helps the body get the nutrients it needs for energy, growth, and repair. List two other systems and explain how they assist with survival. The circulatory system is one of the other important systems in the body. It includes the heart, blood, and blood vessels. The main job of this system is to transport oxygen, nutrients, and hormones to different parts of the body and remove waste products like carbon dioxide. By doing this, the circulatory system helps the body stay balanced and ensures that every cell gets the oxygen and nutrients it needs to survive. Another important system is the respiratory system, which includes the lungs and airways. Its job is to bring oxygen into the body and remove carbon dioxide, a waste product that the body creates.This system is essential for survival because it provides oxygen to the body and gets rid of harmful waste. Objective: Explain that the digestive system is one of those body systems that enable survival, and define the purposes of ingestion, digestion and egestion. Explain how the digestive system assists with survival. The digestive system plays a vital role in keeping the body alive and healthy by breaking down food so the body can absorb the nutrients it needs for energy, growth, and repair. When we eat, the digestive system turns food into smaller molecules like sugars, proteins, and fats that our cells use. These nutrients are absorbed into the bloodstream, providing the body with the energy it needs to function. The digestive system also helps remove waste products that the body doesn't need. Without a properly working digestive system, the body wouldn't get the nutrients it needs, and harmful waste could build up, which would make survival impossible. Define ingestion, digestion and egestion. Ingestion is the process of taking in food and liquids through the mouth. This is the first step in the digestive process. Digestion is the breakdown of food into smaller molecules by both mechanical (chewing) and chemical (enzymes and acids) processes. This allows the body to absorb nutrients. Egestion is the process of eliminating undigested food and waste products from the body, mainly through the anus as faeces. It is the final step in the digestive process, where the body gets rid of things it cannot use. Objective: Compare and contrast, with specific examples, mechanical and chemical digestion. Define mechanical digestion. Provide an example. Mechanical digestion is the physical breakdown of food into smaller pieces without changing its chemical structure. An example of mechanical digestion is chewing. When we chew, our teeth crush and grind the food into smaller pieces, making it easier to swallow and further break down. Define chemical digestion. Provide an example. Chemical digestion is the process by which food is broken down into smaller molecules by the action of enzymes and acids. An example of chemical digestion occurs in the stomach, where stomach acids and enzymes break down proteins in the food we eat, turning them into smaller molecules that can be absorbed by the body. What is the difference between mechanical and chemical digestion? The main difference between mechanical and chemical digestion is that mechanical digestion involves physically breaking down food into smaller pieces (such as chewing), while chemical digestion involves breaking down food into simpler molecules using enzymes and acids. Mechanical digestion doesn't change the food's chemical structure, but chemical digestion does. What happens in the mouth during digestion? In the mouth, both mechanical and chemical digestion begin. The teeth break the food down into smaller pieces (mechanical digestion), while saliva, which contains the enzyme amylase, starts to break down starches into simpler sugars (chemical digestion). The food is then mixed with saliva to form a soft mass called bolus, which is ready to be swallowed. List the 4 different types of teeth. Incisors, canines, pre-molars, molars. Describe the role (function) of incisors. Incisors are the flat, sharp teeth at the front of the mouth. Their main role is to cut food into smaller pieces. They are ideal for biting into food, such as fruits and vegetables. Describe the role (function) of canines. Canines are the pointed teeth located next to the incisors. Their role is to tear food, especially meat. They are designed to grip and rip food apart, helping with the breakdown of tougher substances. Describe the role (function) of pre-molars. Pre-molars are flat-topped teeth located behind the canines. They are used to grind and crush food into smaller pieces, making it easier to swallow. Pre-molars are important for breaking down food before it moves on to the molars. Describe the role (function) of molars. Molars are the large, flat teeth at the back of the mouth. Their main function is to grind and crush food into even smaller pieces, which helps with the digestion process. They are particularly important for breaking down hard food like nuts and meat. Objective: Explain the importance of food as a source of energy, for providing building blocks for growth and repair, and chemicals for regulation and control. List the 5 key nutrients required in a diet. Carbohydrates, proteins, fats, vitamins and minerals. List three examples of vitamins, their role, and food sources. Vitamin A: Important for vision, immune system function, and skin health, found in carrots, sweet potatoes, spinach. Vitamin C: Helps with the growth and repair of tissues, boosts the immune system, and helps the body absorb iron, oranges, strawberries and capsicum. Vitamin D: Helps the body absorb calcium and maintain healthy bones and teeth, found in fatty fish, fortified dairy products. List three examples of minerals, their role, and food sources. Calcium: Essential for strong bones and teeth, muscle function, and nerve signaling, found in dairy products, leafy green vegetables. Iron: Helps form haemoglobin in red blood cells, which carries oxygen throughout the body, found in red meat, beans, fortified cereals. Potassium: Helps regulate fluid balance, nerve signals, and muscle contractions, found in bananas, potatoes, spinach. Why are probiotics important in maintaining a healthy gut microbiome? Probiotics are beneficial bacteria that help maintain a healthy balance in the gut microbiome. They support digestion by helping break down food, absorbing nutrients, and protecting against harmful bacteria. Probiotics can also improve immune function and prevent digestive problems like bloating and irritable bowel syndrome (IBS). A healthy gut microbiome is important for overall health, as it affects not only digestion but also immunity, mood, and even skin health. Objective: Describe the nature of carbohydrates, lipids (fats & oils), and proteins, including their basic chemical structure, roles they play in the body, and food sources. Outline the importance of carbohydrates in our diet. List 3 foods you will find carbohydrates in. Carbohydrates are a key source of energy for the body. When consumed, they are broken down into glucose, which is used by the cells for fuel, especially in the brain and muscles. Carbohydrates help maintain blood sugar levels and provide energy for daily activities, exercise, and bodily functions. Food sources: Bread, rice, pasta. Outline the importance of protein in our diet. List 3 foods you will find protein in. Protein is essential for the growth and repair of tissues, muscles, and cells. It also plays a key role in the production of enzymes, hormones, and antibodies that support immune function. Protein is especially important for building and repairing muscles after physical activity. Food sources: Chicken, eggs, beans. Outline the importance of lipids in our diet. List 3 foods you will find lipids in. Lipids (fats and oils) are important for energy storage, providing a long-term source of energy. They also help in the absorption of fat-soluble vitamins (A, D, E, and K), support cell structure, and maintain healthy skin and organs. Healthy fats, such as omega-3 fatty acids, are also important for heart health. Food sources: Avocados, olive oil, nuts. Draw and describe the chemical structure of a monosaccharide. Provide one example. Glucose Draw and describe the chemical structure of a disaccharide. Provide one example. Sucrose Draw and describe the chemical structure of a polysaccharide. Provide one example. Starch Fats and oils are known as lipids. The chemical structure of them are made up of carbon and hydrogen has three long tails and a short head. What is the key difference between a fats and oils? The key difference between fats and oils is their state at room temperature. Fats are typically solid at room temperature and are usually found in animal products like butter or lard. Oils are typically liquid at room temperature and are usually derived from plants, such as olive oil or vegetable oil. This difference arises due to the types of fatty acids they contain, with fats often having more saturated fatty acids, while oils contain more unsaturated fatty acids. Proteins are very large molecules chemically bonded together by building blocks called amino acids. Objective: Explain the roles of various enzymes and relate their function to the overall role of the digestive system. The enzyme amylase is found in saliva. What does amylase do during digestion? A diagram may help. Amylase is an enzyme found in saliva, and its main role during digestion is to break down starches (complex carbohydrates) into simple sugars like maltose. When you chew food, amylase begins the process of chemical digestion, starting to break down starches in the mouth before the food moves to the stomach. What is the role of pepsin? Describe using a diagram what it does during digestion. Pepsin is an enzyme found in the stomach that breaks down proteins into smaller molecules called peptides. Pepsin is activated in the acidic environment of the stomach and works best in this acidic condition. What 2 important substances are found in the gastric juice of the stomach? Hydrochloric acid and pepsinogen (inactive form of pepsin – which is activated in the acidic environment of the stomach to pepsin). What is the pH of the acid in the stomach? Why is this important for digestion? The pH of the acid in the stomach typically ranges from 1.5 to 3.5, making it highly acidic. This acidic environment is crucial for several reasons. First, it activates pepsinogen into pepsin, an enzyme that breaks down proteins. The acidity also helps kill harmful bacteria and pathogens that may be present in food, preventing infection. Identify the enzyme that breaks down fats and oils. The enzyme that breaks down fats and oils is called lipase. Lipase is produced mainly in the pancreas and secreted into the small intestine, where it breaks down fats into fatty acids and glycerol. Objective: Identify and label each organ in the digestive system and relate their function to the overall role in the digestive system. Can you label each organ of the digestive system? Include a diagram. What happens in the oesophagus during peristalsis? During peristalsis, the oesophagus moves food from the mouth to the stomach through rhythmic contractions of its muscles. These contractions push the food in a wave-like motion, helping it move down the oesophagus and into the stomach. What happens during digestion in the stomach? In the stomach, food is mixed with gastric juices, which contain hydrochloric acid and the enzyme pepsin. The acid helps break down food and kills bacteria, while pepsin begins the process of protein digestion. The stomach muscles also churn the food, turning it into a semi-liquid mixture called chyme before it moves to the small intestine. Identify the organs that involve the secretion of the following enzymes: amylase, pepsin and lipase. Amylase: secreted by the salivary glands in the mouth, and the pancreas. Pepsin: secreted by the stomach Lipase: secreted by the pancreas How long is the small intestine? The small intestine is about 6 metres long. List and outline the role of the three segments of the small intestine during digestion. The small intestine is made up of three segments: the duodenum, jejunum, and ileum. The duodenum is the first part, where most of the chemical digestion occurs. It receives bile from the liver and digestive enzymes from the pancreas to break down fats, proteins, and carbohydrates. The jejunum, the middle section, is where most nutrient absorption takes place, allowing the body to absorb vitamins, minerals, and other nutrients. The ileum, the last part of the small intestine, continues nutrient absorption, specifically of vitamin B12 and bile salts, before the remaining waste moves into the large intestine. Each section plays an important role in the digestion and absorption process. Why are villi in the small intestine important? Villi are tiny finger-like projections in the lining of the small intestine. They increase the surface area for absorption, allowing nutrients to pass into the bloodstream more efficiently. This helps the body absorb vitamins, minerals, and other nutrients from digested food. What organ produces or makes bile? Liver Which organ stores bile? Gallbladder What is the role of bile in digestion? Bile helps digest fats by emulsifying them, which means it breaks large fat droplets into smaller ones. This makes it easier for enzymes like lipase to further break down the fat into fatty acids and glycerol, which can be absorbed in the small intestine. What is the role of the pancreas? The pancreas produces digestive enzymes like amylase, lipase, and proteases, which are released into the small intestine to break down carbohydrates, fats, and proteins. The pancreas also secretes bicarbonate to neutralise stomach acid, creating a more suitable environment for digestion in the small intestine. Why is the appendix considered an important part of the bowel’s immune system? The appendix contains lymphatic tissue and plays a role in immune function, particularly in the development of gut immunity. It helps protect the body from infections and supports the healthy balance of bacteria in the intestines. How long is the large intestine? Around 1.5 metres long. What is the main function of the large intestine? The main function of the large intestine is to absorb water and electrolytes from the remaining indigestible food matter. This helps form solid waste, which is eventually expelled from the body. What do faeces mainly contain? Faeces mainly consist of water, undigested food particles (like fibre), bacteria, cells shed from the lining of the intestines, and waste products from digestion. Experimental Processes How do you test for the following: - Simple sugars (monosaccharides) You can use Benedict’s solution and heat the sample; if it changes colour from blue to orange/red, simple sugars are present. - Disaccharides You can use Benedict’s solution after hydrolysing the disaccharide (by adding acid and heating) to break it down into monosaccharides, then heating it to see a colour change. - Polysaccharides You can use iodine solution, which turns blue-black when it reacts with starch (a polysaccharide). How do you test for fats and oils? The Sudan III test for fats and oils works by adding Sudan III dye to the sample. Sudan III is a red dye that binds to fats and oils, causing them to stain. If fats or oils are present, the sample will form a red-stained layer or show red streaks. This indicates that lipids are present in the sample. Or, rub on brown paper, if transparent then fat/oil is present. How do you test for proteins? You can use Biuret solution, which turns purple when proteins are present. Key Science Skills Can you graph data? Bar graph vs. line graph What goes on the x-axis of a graph? The x axis of a graph typically represents the independent variable. This is the variable that you, as the experimenter, change or manipulate during the experiment. What goes on the y-axis of a graph? The y axis represents the dependent variable. This is the variable that you measure or observe in response to changes in the independent variable. What is an independent variable? The factor or condition that is deliberately changed or manipulated in an experiment. It is what you are testing or investigating to see how it affects the dependent variable. What is a dependent variable? The factor that is measured or observed in an experiment. It depends on the changes made to the independent variable, and it shows the outcome or effect of the experiment. What is the difference between an aim of an experiment and a hypothesis? The aim of an experiment is a statement that describes the purpose or goal of the experiment, outlining what the researcher intends to find or discover. The hypothesis is a specific prediction about what the researcher expects to happen based on prior knowledge or theory. It is a testable statement that suggests a relationship between the independent and dependent variables. Digestion Review Questions 1. Define each of the following: Digestion Digestion is the process where the body breaks down food into smaller molecules that can be absorbed and used for energy. Ingestion Ingestion is the act of taking in food and liquids through the mouth. Egestion Egestion is the removal of undigested food and waste from the body in the form of faeces. Emulsify Emulsify is the process of breaking down large fat droplets into smaller ones to help with digestion. 2. Match the types of teeth with their specific function: Canines Incisors Molars & Premolars Biting and cutting food Incisors Grinding and crushing food Molars & premolars Tearing and grasping food Canines 3. Identify the different types of teeth as being one of the following: incisors, canines, molars or premolars. Pre- Molars Incisors Molars Canines 4. Describe the function of saliva. Saliva helps moisten food, making it easier to chew and swallow. It also contains the enzyme amylase, which starts the process of breaking down starches into simpler sugars. Additionally, saliva helps protect the mouth from infections and keeps the mouth moist. 5. Name the enzyme found in saliva. Amylase 6. Is chewing food an example of mechanical or chemical digestion? Explain. Mechanical digestion as it breaks food down into smaller pieces by tearing, grinding and crushing food. 7. State the name of the: a. Type of digestion that involves enzymes. Chemical digestion b. Enzymes that break down fats. Lipase c. Enzymes that break down proteins. Pepsin 8. Explain why it is important to break down the food that we eat. It is important to break down the food we eat so that the body can absorb essential nutrients like vitamins, minerals, and energy from the food. If food isn't broken down, the body can't use it properly. 9. Describe what happens to enzymes when they get too hot. High temperatures can cause the enzyme's active site to lose its shape, preventing it from binding to the substances it needs to break down so they no longer work properly. 10. State the food group that glucose belongs to. Carbohydrates 11. Name the type of acid that is found in the human stomach. Hydrochloric acid 12. Define ‘chyme’. Chyme is the partially digested, semi‐liquid food that leaves the stomach and enters the small intestine. It is created when food mixes with stomach acids and digestive enzymes. 13. The pH of the stomach is around 1.5. a. Compare the pH of the stomach to vinegar. Stomach acid is more acidic with a pH of around 1, compared to vinegar with a pH of around 3. b. Explain why you think the pH of the stomach is so strong. The pH of the stomach is strong (acidic) to help break down food and activate enzymes like pepsin, which are essential for protein digestion. The acidity also helps kill harmful bacteria and pathogens that may be present in food, protecting the body from infections. 14. Describe the process of peristalsis and suggest why it occurs. Peristalsis is a series of wave‐like muscle contractions that move food through the digestive tract, from the oesophagus to the stomach and then through the intestines. This process occurs to push food along the digestive system, helping break it down and absorb nutrients efficiently. It ensures that food moves in the correct direction and prevents it from going backwards. 15. What is bile? Where is it made? Where is it stored? What is the function of bile? Bile is a digestive fluid that helps break down fats. It is made in the liver and stored in the gallbladder. The function of bile is to emulsify fats, which means breaking large fat droplets into smaller ones, making it easier for enzymes to digest the fat. 16. Use the image below to explain why emulsification is important in digestion. Emulsification is important in digestion because it breaks large fat droplets into smaller ones, increasing the surface area for enzymes like lipase to act on. This makes it easier for the body to digest and absorb fats, allowing nutrients to be efficiently absorbed in the small intestine. 17. Where does emulsification occur in the digestive tract and what causes it? Emulsification occurs in the small intestine, where bile from the liver helps break down large fat droplets into smaller ones. Bile acts as an emulsifier, causing the fats to mix more easily with water and allowing digestive enzymes to further break down the fats. 18. The photomicrograph shows a section of the wall of the small intestine. a. What happens in this part of the digestive system? This is where vital nutrients are absorbed into the bloodstream via villi. b. Identify B and explain how B increases the efficiency of the function of this part of the digestive system. In the small intestine, villi and microvilli play a key role in absorbing nutrients. Villi are tiny, finger‐like projections that line the walls of the small intestine, increasing the surface area for absorption. On the surface of the villi, there are even smaller projections called microvilli, which further increase the surface area. This structure allows for more efficient absorption of nutrients, such as vitamins, minerals, and other small molecules, into the bloodstream. c. Suggest why it is necessary to drink fluids when you suffer from diarrhoea. It is necessary to drink fluids when you suffer from diarrhoea because the body loses a significant amount of water and electrolytes, such as sodium and potassium, through frequent stools. Drinking fluids helps replace these lost fluids, preventing dehydration and helping maintain proper body function. 19. Describe the relationship between: a. Teeth and mechanical digestion. Teeth play a key role in mechanical digestion by physically breaking down food into smaller pieces through chewing. This increases the surface area of food, making it easier for digestive enzymes to act on it. b. The pancreas and the small intestine. The pancreas produces digestive enzymes (like amylase, lipase, and proteases). These enzymes are released into the small intestine, where they help break down carbohydrates, fats, and proteins. c. The liver, gall bladder and the small intestine. The liver produces bile, which is stored in the gall bladder. When food enters the small intestine, the gall bladder releases bile into the small intestine, where it emulsifies fats, helping them to be digested by enzymes. d. The villi, small intestine and capillaries. The villi are tiny projections lining the small intestine that increase the surface area for nutrient absorption. Each villus contains capillaries that absorb nutrients like amino acids, sugars, and vitamins from the digested food into the bloodstream, allowing them to be transported to the rest of the body. e. Bile, lipase and fats. Bile, produced by the liver and stored in the gall bladder, emulsifies large fat droplets, breaking them into smaller droplets. This increases the surface area for lipase, an enzyme produced by the pancreas, to break down fats into fatty acids and glycerol, making them easier to absorb. 20. The following diagram shows the intestine and a blood vessel. Use the diagram to write a statement describing how food passes into the bloodstream. In the small intestine, food is absorbed into the bloodstream through tiny hair‐like structures called villi, which line the walls of the intestine. Each villus contains small blood vessels called capillaries. As food is digested into nutrients (like amino acids, sugars, and fatty acids), these nutrients pass through the cells of the villi. The cells of the villi have tiny openings that allow the nutrients to enter the capillaries. Once inside the capillaries, the nutrients are carried away by the blood and transported to various parts of the body where they are used for energy, growth, and repair. 21. The statements below all describe what happens at different parts of the digestive system. Match each of the following words with one of the statements. Mouth Stomach Duodenum Small Intestine Large Intestine A Water, vitamins and minerals are absorbed. Large intestine B Bile from the liver and gall bladder emulsifies fat into small droplets. Duodenum C Food is mixed with into a soupy mixture with acids and enzymes. Stomach D Food is mechanically broken down into smaller pieces. Mouth E Digested nutrients diffuse through the wall into the bloodstream. Small intestine 22. State the name of the: A Organ in which the digestive process begins. Mouth B Type of digestion in which enzymes secreted by your salivary glands are involved in. Chemical C Slimy, slippery ball‐shape in which your tongue rolls food. Bolus D Muscular contractions that push the ball‐shaped food through the oesophagus to the stomach. Peristalsis E Organ in which most of the absorption of nutrients occurs. Small Intestine F Finger‐shaped structures through which nutrients are absorbed in the organ above. Villi 23. Match the organ with its function in the table shown: Gall Bladder Large Intestine Liver Oesophagus Pancreas Rectum Small Intestine Stomach A Where the breakdown of starch and protein is finished and fat breakdown occurs. Small Intestine B Temporary storage of food and where protein digestion begins. Stomach C Tube that takes food from mouth to stomach. Oesophagus D Stores undigested food and waste while bacteria make some vitamins. Large Intestine E Stores faeces. Rectum F Makes enzymes used in the small intestine. Pancreas G Makes bile, stores glycogen and breaks down toxins. Liver H Stores bile made in the liver until needed in the small intestine. Gall Bladder 24. There are three sections of the small intestine. Match each section with the accurate descriptions. Jejunum Duodenum Ileum A About 25cm Duodenum B The first section of the small intestines. Duodenum C The second section of the small intestines. Jejunum D About 2.5 metres. Jejunum E Primary site where chemical digestion begins. Duodenum F The third section of the small intestines. Ileum G Absorbs any remaining nutrients. Illeum H About 3.5 metres. Illeum I Primarily responsible for absorbing nutrients (contains villi and microvilli to increase surface area for absorption). Jejunum 25. Describe digestion by placing words from the table in the gaps in the following extract. Absorb Digestion Saliva Cells Repair Tract Nutrients Pancreas Digestion is the process of breaking down complex foods into simple nutrients that the body can absorb. The body’s cells need these nutrients for energy, as well as for building materials so the cells can grow and repair themselves. The digestive system consists of: • The digestive tract ‐ series of tubes and cavities that food passes through as it is broken down, and • Other organs that help with digestion, such as the saliva glands, liver and pancreas. The digestive system doesn’t just help with digestion. It is also involved in feeding, absorption and elimination. Reading Comprehension: Read the extract below and use the information to answer the questions. • Highlight key points • Annotate to add information/identify areas to find more information about. Vital Nutrients Carbohydrates play a key role in providing energy for the body. They are the body's primary source of fuel, especially for the brain and muscles during physical activity. Carbohydrates are found in foods like grains, fruits, and vegetables, and they are broken down into glucose, which the body uses for energy. A balanced diet should include carbohydrates, making up about 45‐65% of total daily intake. It's important to choose complex carbohydrates, such as whole grains and vegetables, which provide more nutrients and fibre than simple sugars. Proteins are essential for building and repairing tissues in the body, including muscles, skin, and organs. They are made up of amino acids, some of which the body cannot produce on its own, meaning they must be obtained through food. Protein is also crucial for immune function and the production of hormones and enzymes. Foods like meat, fish, eggs, beans, and nuts are good sources of protein. Protein should account for around 10‐35% of daily calorie intake to support growth, repair, and overall body function. Fats are necessary for energy storage, insulation, and the protection of vital organs. They also play a role in absorbing certain vitamins, such as A, D, E, and K, which are fat‐soluble. Fats come in various forms, including unsaturated fats, which are found in foods like avocados, nuts, and olive oil, and saturated fats, which are found in foods like butter and fatty cuts of meat. A healthy diet should include fats that make up about 20‐35% of daily intake, with a focus on unsaturated fats and limiting the intake of saturated fats to help maintain heart health. Vitamins are organic compounds that the body needs in small amounts for various functions, including immune support, energy production, and bone health. Each vitamin has specific roles; for example, Vitamin C helps with tissue repair, while Vitamin D is important for calcium absorption. Fruits, vegetables, dairy products, and fortified foods are common sources of vitamins. A well‐balanced diet should provide all the necessary vitamins, but there is no exact percentage for vitamin intake, as needs vary based on individual health and activity levels. Minerals are inorganic substances that are vital for processes such as building bones, transmitting nerve impulses, and maintaining heart function. Important minerals include calcium, iron, potassium, and magnesium, which can be found in foods like dairy products, meats, leafy greens, and whole grains. Like vitamins, there isn't a single recommended percentage for mineral intake, but consuming a wide variety of nutrient‐dense foods can ensure adequate mineral intake to support overall health. Water is the most important component of the diet, as it supports every cell and system in the body. Water helps regulate body temperature, remove waste products, and maintain proper digestion and nutrient absorption. While there is no exact percentage of intake for water, a general recommendation is to drink about 8 cups (2 litres) per day, though this can vary depending on factors like activity level, climate, and individual needs. Staying hydrated is essential for overall health and well‐being. 1. Outline the importance of carbohydrates in a healthy diet. Carbohydrates are the body's main source of energy. They are broken down into glucose, which fuels the body's cells, muscles, and brain. Eating enough carbohydrates helps maintain energy levels, supports physical activity, and ensures the proper functioning of the nervous system. 2. How do proteins support the body, and what types of food are good sources of protein? Proteins are essential for building and repairing tissues, making enzymes and hormones, and supporting immune function. Good sources of protein include meat, poultry, fish, eggs, dairy products, beans, lentils, and nuts. 3. What role do fats play in the body? Fats are important for storing energy, protecting organs, and helping absorb fat‐soluble vitamins (A, D, E, and K). They also play a role in maintaining healthy skin and regulating body temperature. Healthy fats can be found in foods like avocados, olive oil, nuts, and fatty fish. 4. How do vitamins contribute to the body’s function, and how can they be obtained from food? Vitamins are essential for a range of bodily functions, including immune support, energy production, and maintaining healthy skin and vision. They can be obtained from a variety of foods, such as fruits, vegetables, dairy products, and whole grains. 5. What are the key functions of minerals in the body, and how can we ensure we are getting enough minerals in our diet? Minerals help with building strong bones and teeth, nerve function, and muscle contraction. They are also important for fluid balance and maintaining a healthy heart. To ensure enough minerals, include a variety of foods like dairy products, leafy greens, nuts, seeds, and meats in your diet. 6. Why is water considered the most important component of the diet, and how much should we aim to drink each day? Water is vital for regulating body temperature, transporting nutrients, and removing waste products. It also aids digestion and keeps the skin healthy. The recommended daily intake varies, but generally, adults should aim to drink about 2 to 2.5 litres (8‐10 cups) of water each day. 7. Identify the recommended daily intake for the nutrients below: Carbohydrates 45 ‐ 65% Protein 10 ‐ 35% Fats 20 ‐ 35% 8. Choose ONE meal that you have consumed this week for dinner. Identify the food sources that contain the following nutrients: Nutrients: Food Source: Carbohydrates Protein Fats Example: Meal ‐ Scrambled eggs on toast with butter Nutrients: Food Source: Carbohydrates 2 x pieces of toast Protein 2 x eggs Milk Fats Butter 9. Using the same meal as above, identify if any of the food sources contained the vitamins and minerals listed below: This will require you to research each food item for the vitamins and minerals it contains. Vitamins & Minerals: Food Source: Purpose in Diet: Vitamin A Vitamin C Vitamin B (Group) Calcium Iron Potassium Example: Meal – scrambled eggs on toast Vitamins & Minerals: Food Source: Purpose in Diet: Vitamin A Eggs, butter Vitamin C Vitamin B (Group) Milk, eggs, butter, bread Calcium Milk, bread Iron Bread Potassium Milk, bread 10. Plan a meal: Your final task is to create a meal (breakfast, lunch or dinner) that includes the vital nutrients that you require in your diet. Meal Ingredients For each ingredient, identify the nutrient(s) that it contains: Food Source: Nutrient(s): Example: Bread Carbohydrates, vitamins (B), minerals (calcium, iron, potassium) Vitamin and Mineral Deficiency Scenario 1: A 25‐year‐old woman who feels very tired all the time, even after getting a full night of sleep. She also notices her skin looks pale and her fingernails are brittle and often break easily. The patient likely has a/an iron deficiency. Evidence: Iron is essential for producing haemoglobin in red blood cells, which carries oxygen throughout the body. A lack of iron can lead to iron‐deficiency anaemia, causing fatigue, pale skin, brittle nails, and other symptoms. Iron deficiency is a common cause of tiredness. Scenario 2: A 30‐year‐old woman who has difficulty seeing in low light, especially at night. She also complains that her skin is dry, and her immune system seems weaker than usual, making her catch colds more easily. The patient likely has a/an Vitamin A deficiency. Evidence: Vitamin A is crucial for maintaining healthy vision, particularly in low light (a condition known as night blindness). It also supports healthy skin, and plays a role in strengthening the immune system. A deficiency in vitamin A can lead to dry skin, a weakened immune response, and poor vision in dim lighting. Scenario 3: A 60‐year‐old man who has been feeling weak and fragile lately. He has noticed some pain in his bones, especially in his lower back, and he often gets fractures from minor falls. He rarely goes outside and does not drink much milk. The patient likely has a/an calcium deficiency. Evidence: Calcium is crucial for maintaining strong bones and teeth, and when calcium levels are low, it can lead to weakened bones, pain, and a higher risk of fractures, especially in older adults. Scenario 4: A 19‐year‐old college student who has noticed that his gums are bleeding when he brushes his teeth. He also has small red spots on his skin and has been feeling more tired than usual. Additionally, he’s had trouble healing from a recent wound on his arm, which seems to be taking longer than normal to close. The patient likely has a/an Vitamin C deficiency. Evidence: Vitamin C is essential for the production of collagen, which is vital for healthy skin, blood vessels, and connective tissues. A lack of vitamin C can lead to weakened blood vessels, causing easy bruising, red spots on the skin (petechiae), bleeding gums, and poor wound healing. Scenario 5: A 30‐year‐old woman who frequently experiences back pain and has noticed her posture is becoming more hunched over time. She has also been feeling weaker, especially in her legs, and is worried about her bones. She doesn't drink milk and rarely eats dairy products, and she spends most of her time indoors. The patient likely has a/an Vitamin D deficiency. Evidence: Vitamin D is necessary for the body to absorb calcium properly, and without enough vitamin D, even if calcium is consumed, it may not be properly utilized. The woman's lack of dairy intake and limited time spent outdoors, where sunlight helps the body produce vitamin D, could be contributing to this deficiency. Scenario 6: A 50‐year‐old man who has been feeling weak, dizzy, and has trouble concentrating at work. He also complains about irregular heartbeats, especially after exercising, and sometimes feels a cramping sensation in his legs. The patient likely has a/an Potassium deficiency. Evidence: Potassium is an essential mineral that helps regulate fluid balance, muscle contractions, and nerve signals, including those related to the heart. Low potassium levels can lead to muscle cramps, weakness, dizziness, and irregular heart rhythms (arrhythmias), particularly after physical exertion. Reading Comprehension: Read the extract below and use the information to answer the questions. Effect of pH on Enzyme Activity Pepsin is an important enzyme in the stomach that helps break down proteins from the food we eat. However, pepsin only works well when the stomach is very acidic. The level of acidity in the stomach is measured by pH, which can range from 0 (very acidic) to 14 (very basic or alkaline). The normal pH in a healthy stomach is between 1.5 and 3.5, which is very acidic. When food enters the stomach, the stomach produces a substance called pepsinogen, which is the inactive form of pepsin. Pepsinogen needs to be turned into active pepsin in order to start breaking down proteins. For pepsinogen to change into pepsin, the stomach needs to be very acidic. This happens when the stomach produces hydrochloric acid (HCl), which lowers the pH to a very acidic level. When the pH is low enough (around 1.5 to 3.5), pepsinogen is activated and turns into pepsin. Once activated, pepsin can start breaking down proteins into smaller parts called peptides. However, if the stomach is not acidic enough (if the pH is higher, like 4 or above), pepsin will not work as well. The enzyme becomes less active and cannot break down proteins as efficiently. 1. Pepsin, unlike amylase and lipase, is only released in the stomach. Explain why pepsin is released in the stomach with reference to the information above. Pepsin is released in the stomach because it is an enzyme that works best in the highly acidic environment of the stomach. It is secreted as an inactive form called pepsinogen, which is then activated by the low pH (acidic conditions) in the stomach. Amylase and lipase, on the other hand, are released in the mouth and small intestine, where the pH is more neutral or slightly alkaline, which is better suited for their activity. 2. What is the role of hydrochloric acid in activating pepsinogen? Hydrochloric acid (HCl) in the stomach provides the highly acidic environment needed to activate pepsinogen, converting it into its active form, pepsin. The low pH (around 1.5 to 2) denatures pepsinogen, allowing it to unfold and activate into pepsin, which then starts breaking down proteins in food. 3. What is the normal pH level for the stomach? The normal pH level for the stomach is typically between 1.5 and 3.5. This acidic environment is crucial for activating enzymes like pepsin and for breaking down food effectively. 4. Taking an antacid can influence the pH level of the acid in the stomach, with strong antacids temporarily raising the pH to 5 – 6. What would effect would this have on digestion during this time? If the pH of the stomach rises to 5–6 due to antacid use, it could impair the digestive process. Pepsin, which works best at a very low pH, would become less effective or inactive at this higher pH level. This would slow down the digestion of proteins, as pepsin plays a key role in protein breakdown. Additionally, the activation of other enzymes that require a low pH, like those in the stomach, could also be affected. 5. What does this information suggest about the pH requirements for the activation of amylase and lipase? Note: To answer this question you will need to know where amylase and lipase are released in the digestive system. Amylase and lipase work best at a more neutral or slightly alkaline pH. Amylase is released in the mouth (and the small intestine) and works best at a neutral pH around 7, while lipase is released in the small intestine, where the pH is slightly alkaline (around 7.5 to 8.5). This suggests that unlike pepsin, which requires an acidic environment for activation, amylase and lipase function in more neutral or slightly alkaline conditions found in the mouth and small intestine. Reading Comprehension: Read the extract below and use the information to answer the questions. The Importance of a Healthy Gut – The Gut‐Brain Axis The gut‐brain axis is the connection between your brain and your gut (the stomach and intestines). This link is important because what happens in your gut can affect how you feel, think, and behave, and vice versa. The brain sends messages to the gut using the nervous system. It controls things like digestion, how fast food moves through your intestines, and how much stomach acid is produced. This is done through the vagus nerve, which is a super‐fast communication line between the brain and gut. The gut can also send signals to the brain. It has its own special system of nerves called the enteric nervous system, sometimes called the "second brain." This system controls digestion and can send messages about hunger, feelings of fullness, and even stress. The gut is also home to millions of tiny bacteria called the microbiome, which can influence the brain. These bacteria produce chemicals that can affect your mood, energy, and even mental health. The bacteria in your gut can produce chemicals like serotonin (which helps regulate mood) and dopamine (which affects motivation and happiness). When the gut microbiome is healthy (balanced), it helps produce these chemicals, making you feel good. But if the gut is unhealthy (imbalanced), it can lead to problems like anxiety, depression, or stress. For example, a diet full of junk food can make the gut microbiome unhappy, and this could affect your brain and how you feel. When you're stressed, your brain sends signals to the gut, which can cause stomach‐aches, nausea, or changes in appetite. On the other hand, if your gut is upset (like when you're sick or have a bad diet), it can make you feel more stressed or anxious. This is why stress and tummy problems are often linked. Taking care of your gut is really important for both your body and your mind. Eating a balanced diet with lots of fibre, fruits, vegetables, and good bacteria (like yogurt) can help keep your gut microbiome happy. This can lead to better mood, less stress, and better overall health. 1. What is the gut‐brain axis? The gut‐brain axis is the connection between your brain and your gut (stomach and intestines). This link is important because what happens in the gut can impact how you feel, think, and behave, and vice versa. 2. How does the brain communicate with the gut? The brain communicates with the gut through the nervous system, controlling digestion, the speed of food movement through the intestines, and stomach acid production. This is done via the vagus nerve, a fast communication line between the brain and the gut. 3. What is the vagus nerve and what role does it play in the gut‐brain axis? The vagus nerve is a crucial communication pathway between the brain and the gut. It plays a role in controlling digestion, the speed at which food moves through the intestines, and the production of stomach acid. 4. What is the ‘second brain’ in the gut, and what does it do? The ‘second brain’ in the gut is the enteric nervous system, a system of nerves that controls digestion. It can also send messages about hunger, feelings of fullness, and even stress, influencing how we feel. 5. How do gut bacteria affect the brain? Gut bacteria can influence the brain by producing chemicals such as serotonin and dopamine, which regulate mood, energy, and mental health. A balanced gut microbiome helps produce these chemicals, making you feel better, while an imbalanced one can negatively affect your mood and mental health. 6. What chemicals produced by the gut can influence your mood and mental health? The gut produces serotonin (which helps regulate mood) and dopamine (which affects motivation and happiness), both of which can influence your mood and mental well‐being. 7. How can an unhealthy gut impact your brain and emotions? An unhealthy or imbalanced gut can lead to mental health issues such as anxiety, depression, or stress. When the gut microbiome is disrupted, it can negatively impact the production of chemicals like serotonin and dopamine, which can affect your emotions and mood. 8. Why can stress cause stomach issues or changes in appetite? Stress can trigger the brain to send signals to the gut, which can lead to stomach aches, nausea, and changes in appetite. This is because the brain and gut are closely linked, and stress can disrupt digestion and gut function. 9. Research: What is meant by ‘gut microbiome’? What does it mean when the gut microbiome is balanced/imbalanced? The gut microbiome refers to the community of bacteria and other microorganisms living in the gut. A balanced microbiome is when the community of bacteria is varied When the gut microbiome is balanced, it means that the beneficial bacteria in your gut are thriving and in the right proportions. This balance helps support healthy digestion, immune function, and the production of important chemicals like serotonin and dopamine, which regulate mood and mental health. A balanced microbiome generally leads to better overall health, including improved mood, energy levels, and reduced risk of conditions like anxiety and depression. When the gut microbiome is imbalanced, it means that harmful bacteria or pathogens may have overtaken the beneficial bacteria, disrupting the gut's natural balance. This imbalance can interfere with digestion, nutrient absorption, and the production of vital brain chemicals. An imbalanced microbiome can contribute to digestive issues, weakened immune function, and even mental health problems like anxiety, depression, or stress. 10. List some ways to keep microbiome in your gut healthy. To keep your gut microbiome healthy, eat a balanced diet rich in fiber, fruits, vegetables, and probiotics (like yogurt). These foods help nourish the beneficial bacteria in your gut, supporting better mood and overall health. 11. How does a poor diet affect both your gut and your brain? A poor diet, especially one high in junk food, can upset the balance of the gut microbiome, which can then negatively affect your brain and emotions. This imbalance can lead to mood disorders like anxiety and depression, as well as affect overall mental well‐being. Reading Comprehension: Read the extract below and use the information to answer the questions. Research Study One The Effect of Probiotics on Anxiety and Depression in Individuals with Gastrointestinal Disorders The study investigated whether taking probiotics (beneficial bacteria) could improve symptoms of anxiety and depression in people who have gastrointestinal (GI) disorders. Researchers wanted to understand if the gut microbiome influences mood and mental health. This study involved 70 participants with GI disorders, such as irritable bowel syndrome (IBS). Half of the participants were given a daily dose of probiotics for 8 weeks, while the other half were given a placebo (a non‐active pill). Before and after the study, the participants completed surveys to measure their levels of anxiety, depression, and GI symptoms. They also had blood samples taken to analyse inflammatory markers and gut health. The results showed that the group who took probiotics had significant improvements in their anxiety and depression symptoms compared to the placebo group. Additionally, the probiotic group reported a decrease in GI symptoms, and blood tests indicated lower levels of inflammation. The study suggests that improving gut health through probiotics may have positive effects on mental health, particularly for individuals with both gastrointestinal issues and mood disorders. 1. What was the aim of the study? The aim of the study was to investigate whether taking probiotics (beneficial bacteria) could improve symptoms of anxiety and depression in people with gastrointestinal (GI) disorders, and to understand if the gut microbiome influences mood and mental health. 2. Identify the independent variable in the study. The independent variable in the study was the daily dose of probiotics, as it was the factor being manipulated to see its effect on anxiety, depression, and GI symptoms. 3. What is a placebo? Why do you think researchers used a placebo in this study? A placebo is a non‐active pill or treatment that looks identical to the actual treatment but has no therapeutic effect. Researchers used a placebo in this study to control for the psychological effect of believing one is receiving treatment (the placebo effect) and to ensure that any changes observed were due to the probiotics and not other factors. 4. Why would diet be difficult to implement as a controlled variable in this study? Diet would be difficult to implement as a controlled variable because it can vary widely among individuals, and participants may have different eating habits or dietary restrictions that could affect gut health and mental health. Ensuring everyone followed the same diet would be challenging and could introduce bias or inconsistencies. 5. How did the researchers measure the participants’ anxiety and depression? The researchers measured the participants' anxiety and depression through surveys completed before and after the study. 6. What were the results of the study for the group taking probiotics? The results showed that the group taking probiotics had significant improvements in their anxiety and depression symptoms compared to the placebo group. They also reported a decrease in GI symptoms, and blood tests indicated lower levels of inflammation. 7. What are the potential implications of this study? (How could the results of this study help people with gastrointestinal disorders?) The potential implications of this study suggest that improving gut health through probiotics may have positive effects on mental health, especially for individuals who suffer from both gastrointestinal issues and mood disorders. The results could lead to the use of probiotics as a complementary treatment for anxiety, depression, and GI symptoms in these individuals, offering a possible alternative or addition to traditional mental health treatments. Reading Comprehension: Read the extract below and use the information to answer the questions. Research Study Two The Role of the Gut‐Brain Axis in Stress and Gut Function This study explored how stress affects gut function and how the brain and gut communicate during stressful situations. Researchers wanted to understand how stress might influence the gut‐brain axis and whether certain changes in gut function could be linked to feelings of stress. The study involved 40 healthy adults who were asked to participate in a stress‐inducing task (public speaking). Before and after the task, researchers measured various physical responses like heart rate and blood pressure. They also collected stool samples to analyse changes in gut microbiota and used questionnaires to assess the participants' emotional state (levels of stress). Additionally, brain scans were used to observe changes in brain activity during the stressful task. The study found that stress had a noticeable effect on both the gut and the brain. Participants showed a shift in their gut microbiota after the stressful task, with an increase in harmful bacteria and a decrease in beneficial bacteria. These changes were linked to higher stress levels. The brain scans showed increased activity in regions of the brain related to stress and emotion. This suggests that stress can alter the gut microbiome and that the gut‐brain axis plays an important role in how stress affects both the mind and body. 1. What was the aim of the study? The aim of the study was to explore how stress affects gut function and how the brain and gut communicate during stressful situations. The researchers wanted to understand how stress might influence the gut‐brain axis and if changes in gut function could be linked to feelings of stress. 2. What method(s) were used to measure stress in the participants? How accurate do you think these measurements would be? Why? Stress was measured using a combination of physical responses (heart rate and blood pressure), stool samples to analyse changes in gut microbiota, questionnaires to assess emotional stress levels, and brain scans to observe changes in brain activity. These methods are likely accurate as they use both physiological (heart rate, blood pressure) and psychological (questionnaires, brain scans) measurements to provide a comprehensive view of how stress affects the body and mind. 3. What changes in the gut microbiota were observed after the stressful task? After the stressful task, there was a noticeable shift in the gut microbiota. There was an increase in harmful bacteria and a decrease in beneficial bacteria. These changes were linked to higher levels of stress. 4. What is the significance of brain activity being measured during a stressful task? Measuring brain activity during a stressful task is significant because it provides insights into how the brain responds to stress and how this may influence emotional and physical responses. Brain scans showing increased activity in regions related to stress and emotion help researchers understand how stress affects both the mind and body, particularly through the gut‐brain axis. 5. How can changes in the gut microbiome affect overall health, based on the study’s results? Changes in the gut microbiome, such as an increase in harmful bacteria and a decrease in beneficial bacteria, can negatively affect overall health. Based on the study’s results, these changes can contribute to digestive issues, immune system dysfunction, and even mental health problems, as the gut and brain are interconnected through the gut‐brain axis. 6. An increase in harmful bacteria in the gut can lead to digestive issues such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). How might the results of this study impact how medical professionals treat a person with IBD and IBS? The results of this study suggest that stress can negatively affect the gut microbiome, potentially worsening conditions like IBD and IBS. Medical professionals might take these findings into account by addressing stress management as part of treatment plans for patients with these conditions. This could involve recommending stress‐reduction techniques, therapy, or probiotics to help manage both the emotional and gastrointestinal aspects of IBD and IBS. Reading Comprehension: Read the extract below and use the information to answer the questions. Digestive Differences The digestive systems of humans, herbivores, and carnivores have some important differences based on the types of food they eat. Humans are omnivores, meaning they eat both plants and animals. Our digestive system is designed to process a variety of foods. We have a relatively short small intestine and stomach compared to herbivores, which allows us to digest a wide range of foods, including both meat and plants. Our stomach is acidic, which helps break down proteins from meat, and we also have enzymes that help digest carbohydrates and fats. In contrast, herbivores, like cows, have a much longer digestive system break down the tough plant materials they eat. Herbivores often have a specialised stomach with multiple chambers. For example, cows have four stomach chambers that allow them to ferment and break down cellulose, a tough fibre found in plants. They also chew their food multiple times to help digest it properly. This is very different from humans, who only have one stomach chamber and don’t need to ferment food to the same extent. The digestive system of horses is different from both humans and cows, mainly due to their herbivorous diet, which consists primarily of fibrous plant material. Like cows, horses rely on the breakdown of plant fibre, but they have a single‐chambered stomach, similar to humans, instead of a multi‐chambered stomach like cows. While humans also have a relatively short digestive tract compared to herbivores, horses have a longer caecum and large intestine, which play a crucial role in fermenting and breaking down cellulose from plants. This makes their digestive system more similar to that of non‐ruminant herbivores (have single chamber stomachs), where fermentation occurs after food passes through the stomach, rather than in a specialized stomach chamber. Unlike cows, who are ruminant herbivores (have multiple chamber stomachs) which ferment food in their stomachs before it is further digested, horses process food mainly in the cecum and colon, which allows for a more continuous, rather than regurgitative, digestion process. This difference is important because it means horses need to eat smaller amounts of food throughout the day to ensure a steady flow of nutrients, while cows can graze and ferment food in larger, less frequent meals. Carnivores, like lions, have a digestive system that is adapted to eating meat. They have a shorter digestive tract because meat is easier to digest than plants. Their stomach is highly acidic and contains powerful enzymes that help break down the proteins in meat. Unlike herbivores, carnivores don’t need to break down tough fibre, so they don’t have a long small intestine. The digestive systems of herbivores, carnivores, and humans are all specialized for their diets, helping them get the nutrients they need to survive. 1. What type of diet do humans have, and how is their digestive system suited for this diet? Humans are omnivores, meaning they eat both plants and animals. Our digestive system is designed to process a variety of foods. We have a relatively short small intestine and stomach, which allows us to digest both meat and plant‐based foods. Our stomach is acidic, helping break down proteins from meat, and we also have enzymes that assist in digesting carbohydrates and fats. 2. Explain the difference between the digestive system of ruminant and non‐ruminant herbivores. Ruminant herbivores, like cows, have a specialized digestive system with multiple stomach chambers (such as four chambers in cows). This allows them to ferment and break down tough plant fibers like cellulose before further digestion. Non‐ruminant herbivores, like horses, have a single‐chambered stomach similar to humans but rely on their larger caecum and large intestine to ferment and break down plant fiber after it passes through the stomach. 3. How do the digestive systems of ruminant and non‐ruminant herbivores influence their eating patterns? Ruminant herbivores, like cows, can graze and eat larger meals less frequently because they ferment food in their multi‐chambered stomachs before further digestion. Non‐ruminant herbivores, like horses, need to eat smaller amounts of food throughout the day to maintain a continuous flow of nutrients, as their digestion process takes place mainly in the cecum and colon after food leaves the stomach. 4. Summarise the differences between the digestive system of humans and ruminant herbivores, such as a cow. Humans have a single‐chambered stomach and a relatively short digestive tract suited for processing a variety of foods. In contrast, ruminant herbivores like cows have multiple stomach chambers (four in cows) for fermenting tough plant material like cellulose. While humans rely on enzymes to break down food directly, cows ferment their food before further digestion, requiring a much longer and more complex digestive system. 5. Summarise the differences between the digestive system of humans and non‐ruminant herbivores, such as a horse. Humans and non‐ruminant herbivores like horses both have single‐chambered stomachs, but horses have a longer caecum and large intestine, which are critical for fermenting and breaking down plant fibre. Humans, with a shorter digestive tract, process food more directly, while horses rely on fermentation after food leaves the stomach, allowing them to digest fibrous plant material more slowly over time. 6. Why do carnivores, such as lions, have a shorter digestive tract compared to herbivores? Carnivores like lions have a shorter digestive tract because meat is easier to digest than plant material. They don’t need to break down tough fibre, so their digestive system is more streamlined. Their highly acidic stomachs and powerful enzymes help quickly digest the proteins in meat, reducing the need for a long digestive tract. 7. Compare the digestive system of a human to a carnivore, such as a lion. Both humans and carnivores like lions have relatively short digestive tracts compared to herbivores. However, lions have a more acidic stomach and powerful enzymes specifically adapted to break down meat proteins, while humans have a more balanced digestive system suited for both plant and animal‐based foods. Humans have enzymes for digesting carbohydrates, fats, and proteins, whereas lions don’t need to process plant fibre, so their stomachs are optimized for meat digestion. Across the whole planet, humans eat on average between 1 and 2.7 kilograms of food a day. That's over 365 kilograms a year per person, and more than 28,800 kilograms over the course of a lifetime. And every last scrap makes its way through the digestive system. Comprised of 10 organs, covering 9 meters, and containing over 20 specialized cell types, this is one of the most diverse complicated systems in the human body. Its parts continuously work in unison to fulfill a singular task, transforming the raw materials of your food into the nutrients and energy that keep you alive. Spanning the entire length of your torso, the digestive system has four main components. First, there's the gastrointestinal tract, a twisting channel that transports your food and has an internal surface area of between 30 and 40 square meters. enough to cover half a badminton court. Second, there's the pancreas, gallbladder, and liver, a trio of organs that break down food using an array of special juices. Third, the body's enzymes, hormones, nerves, and blood all work together to break down food, modulate the digestive process, and deliver its final products. Finally, there's the mesentery, a large stretch of tissue that supports and positions all your digestive organs in the abdomen. enabling them to do their jobs. The digestive process begins before food even hits your tongue. Anticipating a tasty morsel, glands in your mouth start to pump out saliva. We produce about 1.5 liters of this liquid each day. Once inside your mouth, chewing combines with the sloshing saliva to turn food into a moist lump called the bolus. Enzymes present in the saliva break down any starch, Then your food finds itself at the rim of a 25-centimeter-long tube called the esophagus, down which it must plunge to reach the stomach. Nerves in the surrounding esophageal tissue sense the bolus's presence and trigger peristalsis, a series of defined muscular contractions. That propels the food into the stomach, where it's left at the mercy of the muscular stomach walls, which pound the bolus, breaking it into chunks. Hormones secreted by cells in the lining trigger the release of acids and enzyme-rich juices from the stomach wall that start to dissolve the food and break down its proteins. These hormones also alert the pancreas, liver, and gallbladder to produce digestive juices and transfer bile, a yellowish-green liquid that digests fat, in preparation for the next stage. After three hours inside the stomach, the once shapely bolus is now a frothy liquid called chyme, and it's ready to move into the small intestine. The liver sends bile to the gallbladder, which secretes it into the first portion of the small intestine, called the duodenum. Here, it dissolves the fats floating in the slurry of chyme so they can be easily digested by the pancreatic and intestinal juices that have leached onto the scene. for easier absorption into the body. The enzymes also carry out the final deconstruction of proteins into amino acids and carbohydrates into glucose. This happens in the small intestine's lower regions, the jejunum and ileum, which are coated in millions of tiny projections called villi. These create a huge surface area to maximize molecule absorption and transference into the bloodstream. The blood takes them on the final leg of their journey, to feed the body's organs and tissues. But it's not over quite yet. Leftover fiber, water, and dead cells sloughed off during digestion make it into the large intestine, also known as the colon. The body drains out most of the remaining fluid through the intestinal wall. What's left is a soft mass called stool. The colon squeezes this byproduct into a pouch called the rectum, where nerves sense it expanding, and tell the body when it's time to expel the waste. The byproducts of digestion exit through the anus, and the food's long journey, typically lasting between 30 and 40 hours, is finally complete. Go ahead and think for a moment about your very favorite food. What is it? Pizza? Macaroni and cheese? Chicken salad? Sushi? Well, we all have different food preferences, but food is a source of large molecules that are needed for life called biomolecules. There are four major biomolecules that make up all of life, and this will be the focus of this video. Before we get into details about the four biomolecules, we need to talk about one very important vocabulary word, the word monomer. A monomer is a building block. If I had some large substance, the parts that make up the substance are called monomers, just like building blocks. We're going to talk a lot about monomers today because we need to understand what the biomolecules are made of. And we need to understand biomolecules because they're building components of life. So let's introduce the four biomolecules now and talk a little bit about their functions. We'll start with carbohydrates, carbs. Well, carbs are something that you've probably heard a lot about when people are talking about diets. You know, they try to go low carb or maybe they want a lot of carbs. Diets always come and go. Pasta and breads are examples of foods heavy in carbohydrates. Carbs are actually a very important source of energy. In fact, that's one big function of carbs. They are a great, fast source of energy. If you are a marathon runner, you might want to eat a lot of carbs the night before a race. Lots of marathon runners do this. It's called pasta loading. They eat a big pasta dinner the night before they go out on their marathon. Now, carbs have a monomer. Again, remember, monomers are building blocks. The monomer for a carb is a monosaccharide. I know that's a big mouthful, but monosaccharides make up carbohydrates. Next one up is a diverse group known as lipids. Lipids are better known as fats, and they have two different types of building blocks. One type of building block is called a fatty acid, and the other type is called a glycerol. Now, examples of lipids include butter, oil, and cholesterol. Lipids, though, they have a lot of great functions. You might think, well, that's fat. How good can fat be? Well, it just depends when you put it into context. For example, you know those really adorable seals that you see on calendars? They have this fluffy white hair. They're actually called a harp seal. Well, they only look like that when they're babies. When they get older, they're not quite as cute. In their little baby stage, they actually have a lot of this hair that they're born with that keeps them warm. But over time, they have to develop blubber. It's fat, and it helps keep them warm. Lipids are great for insulating. Also, you might not think about fats as being related to energy, but fats are a great source of long-term energy. They can store energy for a long, long time. Say, for example, you wanted to swim the English Channel. That's like 21 miles of swimming. The fastest swimmers might be able to do that in 7 or 8 hours, but it might take a lot longer than that for the average swimmer. More like 25 hours, and that's a lot of swimming. Well, you would want to make sure that your body has enough lipids, enough stored fat, that it can pull upon. Because after you burn off those carbohydrates, remember, carbohydrates, carbs are the fast source of energy, you might not have enough energy storage unless you have some lipids on hand. Lipids also make up cell membranes, so they are very important for life because all living things are made of cells. Of course, an excessive amount of lipids could be a bad thing for your health. Remember, it's all about moderation. Okay, next, proteins. Now when you hear about proteins, a power bars. They say they have a lot of protein in them and that they help with muscle building. Well, protein is great for muscle building. Examples of foods that are high in protein include meats and many types of beans. The monomers of protein are amino acids. So sometimes you see these labels that say, this has 20 amino acids in this food. And really, they're just trying to say that it has protein. Because proteins are made of amino acids, so... That's just some fancy advertising for you. But in addition to being important for muscle development, protein is also very important for other functions, such as working in the immune system and acting as enzymes. Remember, enzymes are made of proteins, so proteins are important for the body. Now, when we start talking about genes, the DNA genes, not the genes you wear, the DNA codes for proteins that are very important for structure and function in the body. The last biomolecule is known as a nucleic acid. Nucleic acids include DNA and RNA, which we'll get to when we get to genetics. They have a monomer called a nucleotide. That's going to be an easy one for you to remember because nucleotide sounds a lot like nucleic acid. And if considering DNA and RNA, both of these are involved in genetic information for the coding of your traits. They are found in a lot of your food because Whenever you eat something that came from something once living, it can still contain the DNA. For example, when you eat a strawberry, you're actually consuming all the cells that make up that strawberry. And in the nucleus of all those strawberry cells is DNA. Plants and animals both have DNA. In fact, any type of life must contain nucleic acids to direct the cell's activities. So we just powered through introducing the four biomolecules by providing examples, exploring their monomers, and giving some general functions. One last very important part to mention is the structure of these biomolecules. Understanding the structure can help with predicting their properties and easily being able to identify them. One thing I like to tell students to do is to write the four biomolecules in the same order that we went through. Carbs, lipids, proteins, and nucleic acids. Then remember this mnemonic device that goes with these four biomolecules. Cho-cho-chan-chomp. Instead of chomp at the end with an M, it's chomp at the end with an N. The C stands for carbon, the H stands for hydrogen, the O for oxygen, so Carbs, lipids, proteins, and nucleic acids all have that CHO in there. It's just that proteins and nucleic acids also have an N, which is nitrogen. And nucleic acids additionally have a P, which is for phosphorus. So again, CHO, CHO, CHON, CHOMP, the major elements in the four biomolecules. Now, these elements are arranged differently in the four biomolecules. It's important to explore the arrangement of the elements in biomolecules because the structure of that arrangement greatly impacts the biomolecule function. So, to the Google to discover some biomolecule arrangement illustrations. Well, that's it for the amoeba sisters, and we remind you to stay curious. Welcome to MooMooMath and Science. In this video I would like to take a look at the movement of food through the digestive system and the enzymes along the way. Enzymes are essential for digestion because they help speed up chemical reactions. One way an enzyme speeds up a chemical reaction is by reducing the amount of energy needed to start the reaction. As food moves along the digestive system enzymes are added along the way. In the mouth or oral cavity salivary glands help start digestion. Lipase is secreted and this helps break down lipids. And amylase is secreted and this helps to break down carbohydrates. From the mouth the food travels down the esophagus and into the stomach. In the stomach several enzymes are secreted. Pepsin is the main enzyme in the stomach. Pepsin breaks down the protein in the food into small particles. Protein digestion therefore starts in the stomach and carbohydrates and lipids start their digestion in the mouth. As food exits the stomach it enters the first portion of the small intestine called the duodenum. The pancreatic duct is located here and releases enzymes produced by the pancreas. This pancreatic juice is a combination of at least 7 different enzymes. This pancreatic juice breaks down proteins, glycogen and starch. Finally as food travels into the small intestine additional enzymes are added. Enzymes whose function is to further break down the chyme released from the stomach. You will find the following enzymes in the small intestine. Lactase is a significant enzyme that breaks down lactose that is found in many dairy products. If you are lactose intolerant you either lack this enzyme or have a reduced amount. So there we go the flow of food and enzymes that help you break down and digest your food. Thanks for watching and MooMooMath uploads a new math and science video every day. Please subscribe and share. And with her new teeth, she can take on more solid foods. Digestion starts in the mouth. Teeth grind up the food. Then, special glands under the tongue pump out saliva to help break down and lubricate the food on its 12-hour, 13-foot journey through the gut. It'll pass from the stomach into the coils of the small intestine before finally passing into the large intestine. Waves of contracting muscle keep the food moving, a process called peristalsis. These contractions are so powerful, we can even eat upside down. For the first time, a new camera shows a high definition view of how food travels through our bodies and into our stomachs. Food enters the stomach through a hole at the top. The stomach is a bag of muscle that churns, squashes and squeezes food into liquid. At the same time acids break the food down. The stomach walls protect themselves with a lining of mucus. Without it, the acids could digest parts of the stomach itself, causing stomach ulcers. About an hour later, the stomach squeezes the broken-down food out through a tiny hole called the pyloric sphincter. The food enters the small intestine, an 11-foot coil of tube where we absorb most of the nutrients. The interior wall of the small intestine is lined with millions of microscopic projections called Vili. These increase the surface area of the gut, making it easier to absorb nutrients. First, the pancreas pumps out a juice that neutralizes stomach acid. Then bile from the liver breaks down the fats into tiny droplets. Smaller droplets are easier for the intestine to absorb. After an hour and a half, the small intestine has absorbed most of the nutrients from the food. It's time for what remains to move on. It enters the large intestine through this, the ileocecal sphincter, a valve that keeps our food from going back where it came from. What's left is a mix of waste food and dead cells from the walls of the gut. The large intestines main job is to extract water from it. Lots of bacteria live here too. But it isn't because of an infection. We actually need them. They produce enzymes that break down complex carbohydrates in our food. Carbohydrates we couldn't otherwise digest. Finally, after about 12 hours, we expel what's left of our first meal. Year 8 Digestion Test 2023 - Solutions Multiple Choice Section 1. C – Peristalsis 2. B – Stomach 3. B – Bolus 4. D 5. C 6. A – Decrease fat digestion 7. B – 90mg/ml Short Answer Section 8. F T T T 9. a. Breaking down/digesting the food we eat (owtte) b. Glucose/ Simple sugar c. Mono-saccharide d. Has drawn at least 3 single hexagons 10. a. Iodine b. Any answer denoting a colour change to dark blue/black c. Benedict’s d. Reference to adding sample, water and Benedict’s to a test tube [1 mark] Method of heating the sample [1 mark] Reference to colour change to orange/red (reference to original blue colour not needed) [1 mark] 11. Correct labels for: [4 marks: 0.5 marks each] 12. a. Digestion of protein b. pH 7 (allow between 6.75-7.25) c. Identification of basic/alkaline environment [1 mark] Reference to optimum pH of trypsin being 9-9.5 [1 mark] 13. Credit any correct responses which may not be listed below in the table. Half a mark each for 2 sources in final column. Website with information on all vitamins (scroll down): https://www.medicalnewstoday.com/articles/195878#supplements Vitamin [1 mark] What it does [1 mark] Where we get it [1 mark] A Healthy eyesight Healthy skin Fresh vegetables Eggs B group Obtaining energy from foods Growth Formation of RBCs Making DNA/RNA Maintaining the nervous system Dairy Fish Meat Eggs Fortified cereals Leafy vegetables C Immunity Wound healing Bone formation Citrus fruits Fresh fruit Fresh vegetables Body Systems: Digestion Year 8 Science Learning Intention Explain that multicellular organisms contain systems of organs that carry out specialised functions that enable them to survive (and reproduce). Body Systems • In multicellular organisms, body systems work together to maintain homeostasis and support the organism’s survival by performing specialised functions. • These systems are interdependent, ensuring the organism can grow, reproduce, and adapt to its environment. • Each system has a specific role such as: • Delivering oxygen (respiratory system) • Transporting nutrients & waste (circulatory system) • Breaking down food for energy (digestive system) • Coordinating responses (nervous system) Cell: The smallest unit of life Tissue: Group of cells similar in structure that perform a specific function. Organ: Structures made up of different types of tissue that perform specific functions. Body/Organ System: Groups of organs within our bodies that carry out specific functions. Working Together? Organs (Working Together) • A collection of organs will work together to achieve a purpose such as: • Enabling digestion • Transmitting blood and oxygen around the body • To remove wastes from the body • To send messages around the body • To assist with movement and structural support • When a set of organs work together, they make up a body system. Body Systems Digestive System: Collection of organs that help to break down food so that it can be absorbed by the body. Respiratory System: Helps to bring in oxygen and remove carbon dioxide. Circulatory System: Delivery system which carries oxygen and nutrients around the body via blood. Excretory System: Removes waste products from the body. Nervous System: Sends and receives messages throughout the body. Reproductive System: Enables to production of offspring. Musculoskeletal System: Includes the muscles and the skeleton which helps to move and support the body. Learning Intention Explain that the digestive system is one of those body systems that enable survival, and define the purposes of ingestion, digestion and egestion. What is Digestion? • Digestion involves a series of processes that break down the food you consume so that the nutrients are small enough to be absorbed into your blood. • Key Terms: Ingestion Process of taking food and drink into the body through the mouth. Egestion Process of expelling undigested and unabsorbed food material from the digestive system as waste. Digestive Processes • This involves five processes before egestion occurs: • ingestion • mechanical digestion • chemical digestion • absorption • assimilation Ingestion: Consuming food Mechanical Digestion: Physically breaking down food into smaller pieces using your teeth. Chemical Digestion: Enzymes will assist in helping to break down food into smaller pieces. Absorption: Small finger shaped structures lining the small intestine known as villi take in (absorb) the nutrients from the food you consumed. Assimilation: The nutrients from the food are converted into chemicals in your cells so they can be used by the body as energy. Learning Intention Compare and contrast, with specific examples, mechanical and chemical digestion. Digestion: Mechanical and Chemical Aspect Mechanical Digestion Chemical Digestion Definition Physical breakdown of food into small pieces. Chemical breakdown of food into smaller pieces. Processes Involves physical actions such as chewing, churning and grinding. Involves enzymes and chemical reactions. Primary Function Prepares food for chemical digestions by increasing surface area. Converts food into absorbable molecules like amino acids, glucose and fatty acids. Location Mouth, stomach, and intestines. Mouth, stomach and small intestines. Involvement of Does not involved enzymes. Enzymes (catalysts that speed up chemical reactions) Involves enzymes like amylase, lipase and pepsin. Examples Saliva (contains enzyme amylase that breaks down carbohydrates). Chewing Food needs to be broken down so that the nutrients can be absorbed into the bloodstream. Mechanical Digestion (Physical Digestion) • Food is taken in through the mouth and broken down using your teeth. • Using our teeth allows us to: • Bite • Tear • Crush • Grind • Once the teeth physically break down the food into smaller pieces, the tongue rolls the food until it is in a ball like shape. • This ball like collection of food is known as a ‘bolus’. Chemical Digestion • Chemical digestion occurs due to enzymes which help to break down the foods using a chemical process. • Enzymes are proteins that act as biological catalysts, meaning they speed up reactions without being used up. • Enzymes are used in the digestive system to break large, complex, insoluble food molecules into small, simple, soluble molecules so they can be absorbed into the bloodstream. • Different types of enzymes can break down different nutrients. Learning Intention Explain the importance of food as a source of energy, for providing building blocks for growth and repair, and chemicals for regulation and control. Describe the nature of carbohydrates, lipids (fats & oils), and proteins, including their basic chemical structure, roles they play in the body, and food sources. What are Nutrients? • Nutrients are substances that living organisms need to survive, grow, and function properly. • They are characterized into six main groups: • Carbohydrates • Proteins • Fats • Vitamins • Minerals • Water The digestive system helps to break down food so that the nutrients can be absorbed in a form that can be used by the body. Carbohydrates • Provide the body with energy. • Found in food sources such as bread, rice, fruits and vegetables. Simple Carbohydrates Complex Carbohydrates Made of one or two sugar units. Made of many sugar units linked together. Quickly broken down into glucose, leading to a rapid spike in blood sugar. Broken down more slowly into glucose, providing steady energy release. Found in sugary foods such as fruits, lollies and soft drinks. Found in whole grains, vegetables and legumes. Example: Glucose (monosaccharide) & sucrose (disaccharide) Example: Starch (polysaccharide) Types of Carbohydrates Monosaccharide Disaccharide Polysaccharide Single sugar unit Two sugar units joined Many sugar units joined together Glucose Fructose Examples of foods? Sucrose Starch Examples of foods? Take less time to digest Take longer to digest Protein • Required for the body to build and repair tissues, like muscles, skin and organs. • Essential for growth and healing. • Made of smaller building blocks called amino acids. • Found in food sources such as: • Meat • Eggs • Beans • Nuts Fats • Provide energy and help the body to absorb nutrients. • Made of molecules called triglycerides. • Essential for protecting organs and storing energy. • Fats are found in food sources such as: • Oils • Butter • Nuts • Fatty fish Vitamins & Minerals • Vitamins & minerals are vital for immune system functioning and body development. • Vitamins are made by plants and animals. • Examples include: • Vitamin A • Vitamin C • Vitamin B group • Minerals are inorganic elements that are found in soil & water – which are then ingested by animals or absorbed by plants. • Examples include: • Calcium • Iron • Potassium VITAMIN A (Fat Soluble) What we need it for: Food Sources: • Immune system functioning • Healthy eye sight • Skin (vitamin A is also known as retinol) • • • • • • Signs of Deficiency: Carrots • Night blindness Dark green vegetables • Dry skin Fish Eggs Dairy Liver Too much: • • • • Blurred vision Headaches Organ damage Skin conditions VITAMIN C (Water Soluble) What we need it for: Food Sources: • Immunity • Maintaining healthy skin • Wound healing • • • • Citrus fruits Strawberries Broccoli Brussel Sprouts Signs of Deficiency: Too much: • Scurvy (weakness, • Diarrhea anemia, gum disease) VITAMIN B Group (Water Soluble) Group of Vitamins that includes (amongst others): • Thiamin (B1) • Riboflavin (B2) • Folate (B9) What we need it for: Food Sources: • Obtaining energy from • Meat food. • Fish • Dairy • Vegetables • Nuts Signs of Deficiency: Too much: • Lack of energy • Nausea • Diarrhea CALCIUM What we need it for: Food Sources: Signs of Deficiency: Too much: • Healthy bones and teeth • Blood clotting • Muscles contraction & relaxation • Dairy products • Leafy green vegetables • Osteoporosis (long term) • Weak nails • Hair breakage • Fatigue • Kidney stones IRON What we need it for: Food Sources: Signs of Deficiency: Too much: • Makes haemoglobin (part of red blood cells that transports oxygen to cells) • Red meat • Green leafy vegetables • Eggs • Chicken • Fish • Anemia • Stomach ulcers POTASSIUM What we need it for: Food Sources: • Maintains body fluids • Muscle contractions • Nerve signals • • • • Bananas Sweet potatoes Oranges Green leafy vegetables Signs of Deficiency: Too much: • Muscle weakness • Muscle cramps • Fatigue • Heart palpitations • Shortness of breath Learning Intention Explain what happens to carbohydrates, proteins and lipids (fats and oils) during digestion. Explain the roles of various digestive enzymes. Breaking Down Carbohydrates Breaking Down Protein Breaking Down Fats Learning Intention Identify and label each organ in the digestive system and relate their function to the overall role in the digestive system. Relate to the conditions under which various digestive enzymes operate within the organs of the digestive system. Processes of Digestion Mouth (To the Oesophagus) • Teeth: Involved in the mechanical breakdown of food into smaller pieces. • This will assist with chemical digestion. • Saliva: Enzyme in salvia called ‘amylase’ secreted. • Breaks down carbohydrates • Tongue: Rolls food into a ball known as ‘bolus’. Oesophagus (To the Stomach) • The bolus is sent down the oesophagus through a process called ‘peristalsis’. • Peristalsis involves muscle contractions which help to push the bolus down towards the stomach. Stomach (To the small intestine) • The stomach is an organ that also plays a role in mechanical and chemical digestion. • Mechanical Digestion: The stomach churns which helps to mix up the food with the gastric juice that is contained in the stomach. • Chemical Digestion: The gastric juice starts to break down the proteins within the stomach. • The stomach can store the contents until it is ready to go through the next process in digestion. • This can take from 2 to 6 hours (depending on the source). • Pepsin is secreted (activated by the acidic nature of the gastric juices) to begin breakdown of protein. Chyme: Semi-liquid mixture of partially digested food. Created in the stomach when churning occurs. Small Intestine (To the Large Intestine) • Named the ‘small’ intestine due to the narrow width. • The small intestine is about 6 metres in length. • There are three sections. • Food travels through the small intestine through the process of peristalsis. • This is where the nutrients are absorbed. • Small finger-like structures called ‘villi’ line the small intestine and absorb the nutrients into the blood stream. Small Intestine • Mechanical Digestion: • Segmentation: Contractions of the small intestine wall that continues to mix chyme with digestive enzymes and bile, increasing contact with the lining of the intestine wall. • Bile is secreted (breaks down fats and oils – no chemical reaction/new substance created) • Chemical Digestion: • Enzymes are secreted: • Amylase (breaks down carbohydrates) • Lipase (breaks down fats) • Pepsin (breaks down protein) Small Intestine Segments Duodenum Around 25cm • Site where chemical digestion begins in the intestine. • Receives chyme from the stomach. • Mixes with bile from the liver and gall bladder to emulsify fats. • Mixes with digestive enzymes from the pancreas (neutralises stomach acids). Jejunum Around 2.5m • Primarily responsible for absorbing nutrients such as carbohydrates (glucose), proteins (as amino acids) and vitamins & minerals. • Contains dense villi and microvilli. Ileum Around 3.5m • Absorbs remaining nutrients Large Intestine (To the Rectum & Anus) • The large intestine gets its name from the width which is greater than that of the small intestine. • It is about 1.5 metres in length. • Most of the nutrients have already been absorbed by the time it reaches the large intestine, but some vitamins can still be found. • It absorbs water from the substance, resulting in a firmer product. • The large intestine transmits this now waste product from the food out of the body. Rectum & Anus • The rectum stores the remaining faecal matter as it waits to be removed from the body. • When the rectum starts to stretch to accommodate the waste product, a signal is sent to the brain which is interpreted as a need to go to the bathroom. • The anus is a ring of muscle which will remain closed when not needed. • When removing waste, the anus will stretch open to allow the waste product to exit the body. Additional Components of Digestion Liver & Gall Bladder • Both assist in the break down of fats and oils within food. • The liver produces a green substance known as ‘bile’ which breaks down the fats and oils. • The gall bladder stores the bile for when the food reaches the small intestine. Pancreas • Makes ‘pancreatic juice’. • This juice assists in helping to neutralise stomach acid. • The pancreas also creates enzymes which are used to chemically break down food. 1. Food is ingested through the mouth. Chemical Digestion: Break down of food through enzyme in saliva. Mechanical Digestion: Break down of food through teeth (tongue then rolls food into ball called ‘bolus’). 2. Bolus is then pushed down oesophagus through a process known as peristalsis. 3. Bolus enters the stomach. Chemical Digestion: Acids in the stomach further break down the food. Mechanical Digestion: The stomach churns the food. 4. Food enters the small intestine which is lined with finger like structures known as ‘villi’ which absorb the nutrients. 5. The remaining mass then passes through the large intestine where the remaining nutrients and the water are absorbed. 6. The waste is stored in the rectum and when full, will send a signal to be released via the anus (egestion). Digestive Explosions Burping When a build up of gas is released from the mouth. Occurs when air is taken in too quickly (through talking whilst eating, eating/drinking too quickly). Heartburn Burning sensation in the chest that occurs when stomach acid rises up into the oesophagus Flatulence The passing of wind. Due to gases that build up in the large intestine which are created by the presence of bacteria. Diarrhoea When undigested food moves too quickly through the small and then large intestine. Due to presence of bacteria, villi can swell, therefore not absorbing nutrients. The large intestine then passes the substance through too fast to absorb any water, resulting in the expulsion of watery faeces. Vomiting When stomach contents is forcefully ejected out of the stomach, up the oesophagus and through the mouth.  D Bone health Immunity Sunlight Fish Eggs Liver 14. A bar graph shown like: with 1 mark for x-axis label, 1 mark for bars and 1 mark for y axis scaling Distance along the small intestine (cm) b) Villi create a larger surface area [1 mark] Reference to this increasing the rate of digestion/absorption of food into the blood [1 mark] c) 1 mark describing the data The concentration of glucose increases from 50 – 500 from 100cm distance through to 300cm distance along the small intestine and drops from 500 (to 250 after 500cm) back down to 0 at 700cm. Units? Mol/dm-3 not sure if needed at Yr 8 level, but some reference point of numbers needed 1 mark for stating that the concentration of glucose increases due to carbohydrates broken down / digested into sugars (glucose) And 1 mark for stating the reduction in glucose is where the glucose would then be absorbed into blood stream Body Systems: Digestion Year 8 Science Learning Intention Explain that multicellular organisms contain systems of organs that carry out specialised functions that enable them to survive (and reproduce). Body Systems • In multicellular organisms, body systems work together to maintain homeostasis and support the organism’s survival by performing specialised functions. • These systems are interdependent, ensuring the organism can grow, reproduce, and adapt to its environment. • Each system has a specific role such as: • Delivering oxygen (respiratory system) • Transporting nutrients & waste (circulatory system) • Breaking down food for energy (digestive system) • Coordinating responses (nervous system) Cell: The smallest unit of life Tissue: Group of cells similar in structure that perform a specific function. Organ: Structures made up of different types of tissue that perform specific functions. Body/Organ System: Groups of organs within our bodies that carry out specific functions. Working Together? Organs (Working Together) • A collection of organs will work together to achieve a purpose such as: • Enabling digestion • Transmitting blood and oxygen around the body • To remove wastes from the body • To send messages around the body • To assist with movement and structural support • When a set of organs work together, they make up a body system. Body Systems Digestive System: Collection of organs that help to break down food so that it can be absorbed by the body. Respiratory System: Helps to bring in oxygen and remove carbon dioxide. Circulatory System: Delivery system which carries oxygen and nutrients around the body via blood. Excretory System: Removes waste products from the body. Nervous System: Sends and receives messages throughout the body. Reproductive System: Enables to production of offspring. Musculoskeletal System: Includes the muscles and the skeleton which helps to move and support the body. Learning Intention Explain that the digestive system is one of those body systems that enable survival, and define the purposes of ingestion, digestion and egestion. What is Digestion? • Digestion involves a series of processes that break down the food you consume so that the nutrients are small enough to be absorbed into your blood. • Key Terms: Ingestion Process of taking food and drink into the body through the mouth. Egestion Process of expelling undigested and unabsorbed food material from the digestive system as waste. Digestive Processes • This involves five processes before egestion occurs: • ingestion • mechanical digestion • chemical digestion • absorption • assimilation Ingestion: Consuming food Mechanical Digestion: Physically breaking down food into smaller pieces using your teeth. Chemical Digestion: Enzymes will assist in helping to break down food into smaller pieces. Absorption: Small finger shaped structures lining the small intestine known as villi take in (absorb) the nutrients from the food you consumed. Assimilation: The nutrients from the food are converted into chemicals in your cells so they can be used by the body as energy. Learning Intention Compare and contrast, with specific examples, mechanical and chemical digestion. Digestion: Mechanical and Chemical Aspect Mechanical Digestion Chemical Digestion Definition Physical breakdown of food into small pieces. Chemical breakdown of food into smaller pieces. Processes Involves physical actions such as chewing, churning and grinding. Involves enzymes and chemical reactions. Primary Function Prepares food for chemical digestions by increasing surface area. Converts food into absorbable molecules like amino acids, glucose and fatty acids. Location Mouth, stomach, and intestines. Mouth, stomach and small intestines. Involvement of Does not involved enzymes. Enzymes (catalysts that speed up chemical reactions) Involves enzymes like amylase, lipase and pepsin. Examples Saliva (contains enzyme amylase that breaks down carbohydrates). Chewing Food needs to be broken down so that the nutrients can be absorbed into the bloodstream. Mechanical Digestion (Physical Digestion) • Food is taken in through the mouth and broken down using your teeth. • Using our teeth allows us to: • Bite • Tear • Crush • Grind • Once the teeth physically break down the food into smaller pieces, the tongue rolls the food until it is in a ball like shape. • This ball like collection of food is known as a ‘bolus’. Chemical Digestion • Chemical digestion occurs due to enzymes which help to break down the foods using a chemical process. • Enzymes are proteins that act as biological catalysts, meaning they speed up reactions without being used up. • Enzymes are used in the digestive system to break large, complex, insoluble food molecules into small, simple, soluble molecules so they can be absorbed into the bloodstream. • Different types of enzymes can break down different nutrients. Learning Intention Explain the importance of food as a source of energy, for providing building blocks for growth and repair, and chemicals for regulation and control. Describe the nature of carbohydrates, lipids (fats & oils), and proteins, including their basic chemical structure, roles they play in the body, and food sources. What are Nutrients? • Nutrients are substances that living organisms need to survive, grow, and function properly. • They are characterized into six main groups: • Carbohydrates • Proteins • Fats • Vitamins • Minerals • Water The digestive system helps to break down food so that the nutrients can be absorbed in a form that can be used by the body. Carbohydrates • Provide the body with energy. • Found in food sources such as bread, rice, fruits and vegetables. Simple Carbohydrates Complex Carbohydrates Made of one or two sugar units. Made of many sugar units linked together. Quickly broken down into glucose, leading to a rapid spike in blood sugar. Broken down more slowly into glucose, providing steady energy release. Found in sugary foods such as fruits, lollies and soft drinks. Found in whole grains, vegetables and legumes. Example: Glucose (monosaccharide) & sucrose (disaccharide) Example: Starch (polysaccharide) Types of Carbohydrates Monosaccharide Disaccharide Polysaccharide Single sugar unit Two sugar units joined Many sugar units joined together Glucose Fructose Examples of foods? Sucrose Starch Examples of foods? Take less time to digest Take longer to digest Protein • Required for the body to build and repair tissues, like muscles, skin and organs. • Essential for growth and healing. • Made of smaller building blocks called amino acids. • Found in food sources such as: • Meat • Eggs • Beans • Nuts Fats • Provide energy and help the body to absorb nutrients. • Made of molecules called triglycerides. • Essential for protecting organs and storing energy. • Fats are found in food sources such as: • Oils • Butter • Nuts • Fatty fish Vitamins & Minerals • Vitamins & minerals are vital for immune system functioning and body development. • Vitamins are made by plants and animals. • Examples include: • Vitamin A • Vitamin C • Vitamin B group • Minerals are inorganic elements that are found in soil & water – which are then ingested by animals or absorbed by plants. • Examples include: • Calcium • Iron • Potassium VITAMIN A (Fat Soluble) What we need it for: Food Sources: • Immune system functioning • Healthy eye sight • Skin (vitamin A is also known as retinol) • • • • • • Signs of Deficiency: Carrots • Night blindness Dark green vegetables • Dry skin Fish Eggs Dairy Liver Too much: • • • • Blurred vision Headaches Organ damage Skin conditions VITAMIN C (Water Soluble) What we need it for: Food Sources: • Immunity • Maintaining healthy skin • Wound healing • • • • Citrus fruits Strawberries Broccoli Brussel Sprouts Signs of Deficiency: Too much: • Scurvy (weakness, • Diarrhea anemia, gum disease) VITAMIN B Group (Water Soluble) Group of Vitamins that includes (amongst others): • Thiamin (B1) • Riboflavin (B2) • Folate (B9) What we need it for: Food Sources: • Obtaining energy from • Meat food. • Fish • Dairy • Vegetables • Nuts Signs of Deficiency: Too much: • Lack of energy • Nausea • Diarrhea CALCIUM What we need it for: Food Sources: Signs of Deficiency: Too much: • Healthy bones and teeth • Blood clotting • Muscles contraction & relaxation • Dairy products • Leafy green vegetables • Osteoporosis (long term) • Weak nails • Hair breakage • Fatigue • Kidney stones IRON What we need it for: Food Sources: Signs of Deficiency: Too much: • Makes haemoglobin (part of red blood cells that transports oxygen to cells) • Red meat • Green leafy vegetables • Eggs • Chicken • Fish • Anemia • Stomach ulcers POTASSIUM What we need it for: Food Sources: • Maintains body fluids • Muscle contractions • Nerve signals • • • • Bananas Sweet potatoes Oranges Green leafy vegetables Signs of Deficiency: Too much: • Muscle weakness • Muscle cramps • Fatigue • Heart palpitations • Shortness of breath Learning Intention Explain what happens to carbohydrates, proteins and lipids (fats and oils) during digestion. Explain the roles of various digestive enzymes. Breaking Down Carbohydrates Breaking Down Protein Breaking Down Fats Learning Intention Identify and label each organ in the digestive system and relate their function to the overall role in the digestive system. Relate to the conditions under which various digestive enzymes operate within the organs of the digestive system. Processes of Digestion Mouth (To the Oesophagus) • Teeth: Involved in the mechanical breakdown of food into smaller pieces. • This will assist with chemical digestion. • Saliva: Enzyme in salvia called ‘amylase’ secreted. • Breaks down carbohydrates • Tongue: Rolls food into a ball known as ‘bolus’. Oesophagus (To the Stomach) • The bolus is sent down the oesophagus through a process called ‘peristalsis’. • Peristalsis involves muscle contractions which help to push the bolus down towards the stomach. Stomach (To the small intestine) • The stomach is an organ that also plays a role in mechanical and chemical digestion. • Mechanical Digestion: The stomach churns which helps to mix up the food with the gastric juice that is contained in the stomach. • Chemical Digestion: The gastric juice starts to break down the proteins within the stomach. • The stomach can store the contents until it is ready to go through the next process in digestion. • This can take from 2 to 6 hours (depending on the source). • Pepsin is secreted (activated by the acidic nature of the gastric juices) to begin breakdown of protein. Chyme: Semi-liquid mixture of partially digested food. Created in the stomach when churning occurs. Small Intestine (To the Large Intestine) • Named the ‘small’ intestine due to the narrow width. • The small intestine is about 6 metres in length. • There are three sections. • Food travels through the small intestine through the process of peristalsis. • This is where the nutrients are absorbed. • Small finger-like structures called ‘villi’ line the small intestine and absorb the nutrients into the blood stream. Small Intestine • Mechanical Digestion: • Segmentation: Contractions of the small intestine wall that continues to mix chyme with digestive enzymes and bile, increasing contact with the lining of the intestine wall. • Bile is secreted (breaks down fats and oils – no chemical reaction/new substance created) • Chemical Digestion: • Enzymes are secreted: • Amylase (breaks down carbohydrates) • Lipase (breaks down fats) • Pepsin (breaks down protein) Small Intestine Segments Duodenum Around 25cm • Site where chemical digestion begins in the intestine. • Receives chyme from the stomach. • Mixes with bile from the liver and gall bladder to emulsify fats. • Mixes with digestive enzymes from the pancreas (neutralises stomach acids). Jejunum Around 2.5m • Primarily responsible for absorbing nutrients such as carbohydrates (glucose), proteins (as amino acids) and vitamins & minerals. • Contains dense villi and microvilli. Ileum Around 3.5m • Absorbs remaining nutrients Large Intestine (To the Rectum & Anus) • The large intestine gets its name from the width which is greater than that of the small intestine. • It is about 1.5 metres in length. • Most of the nutrients have already been absorbed by the time it reaches the large intestine, but some vitamins can still be found. • It absorbs water from the substance, resulting in a firmer product. • The large intestine transmits this now waste product from the food out of the body. Rectum & Anus • The rectum stores the remaining faecal matter as it waits to be removed from the body. • When the rectum starts to stretch to accommodate the waste product, a signal is sent to the brain which is interpreted as a need to go to the bathroom. • The anus is a ring of muscle which will remain closed when not needed. • When removing waste, the anus will stretch open to allow the waste product to exit the body. Additional Components of Digestion Liver & Gall Bladder • Both assist in the break down of fats and oils within food. • The liver produces a green substance known as ‘bile’ which breaks down the fats and oils. • The gall bladder stores the bile for when the food reaches the small intestine. Pancreas • Makes ‘pancreatic juice’. • This juice assists in helping to neutralise stomach acid. • The pancreas also creates enzymes which are used to chemically break down food. 1. Food is ingested through the mouth. Chemical Digestion: Break down of food through enzyme in saliva. Mechanical Digestion: Break down of food through teeth (tongue then rolls food into ball called ‘bolus’). 2. Bolus is then pushed down oesophagus through a process known as peristalsis. 3. Bolus enters the stomach. Chemical Digestion: Acids in the stomach further break down the food. Mechanical Digestion: The stomach churns the food. 4. Food enters the small intestine which is lined with finger like structures known as ‘villi’ which absorb the nutrients. 5. The remaining mass then passes through the large intestine where the remaining nutrients and the water are absorbed. 6. The waste is stored in the rectum and when full, will send a signal to be released via the anus (egestion). Digestive Explosions Burping When a build up of gas is released from the mouth. Occurs when air is taken in too quickly (through talking whilst eating, eating/drinking too quickly). Heartburn Burning sensation in the chest that occurs when stomach acid rises up into the oesophagus Flatulence The passing of wind. Due to gases that build up in the large intestine which are created by the presence of bacteria. Diarrhoea When undigested food moves too quickly through the small and then large intestine. Due to presence of bacteria, villi can swell, therefore not absorbing nutrients. The large intestine then passes the substance through too fast to absorb any water, resulting in the expulsion of watery faeces. Vomiting When stomach contents is forcefully ejected out of the stomach, up the oesophagus and through the mouth. Using all this information, create the most detailed ever list of comprehensive notes and don't remove anything thats specific and important Okay, so I need to create really detailed notes on digestion for my Year 8 Science test. Let me start by looking through all the information provided. There's the Digestion Checklist Answers, Digestion Notes, a PowerPoint presentation, Practice Test Answers, some YouTube links, and additional explanations. I should organize this into sections based on the checklist objectives. First, the checklist mentions explaining multicellular organisms' systems. The digestive system's role is breaking down food and absorbing nutrients. Other systems like circulatory and respiratory assist by transporting oxygen and removing waste. I need to outline these clearly. Next, the objectives on ingestion, digestion, egestion. I have definitions for each. Also, comparing mechanical and chemical digestion. Chewing is mechanical, enzymes in the stomach are chemical. The mouth starts both processes with teeth and saliva. Types of teeth: incisors, canines, premolars, molars. Each has a function like cutting, tearing, grinding. Nutrients: carbohydrates, proteins, lipids, vitamins, minerals. Examples and their roles. Testing for each nutrient—Benedict's for sugars, iodine for starch, Biuret for proteins, Sudan III for fats. The experiments section also mentions graphing data, variables, and hypothesis vs. aim. Organs of the digestive system: mouth, esophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine, liver, gallbladder, pancreas. Functions of each, enzymes they secrete. Villi in the small intestine increase absorption area. Enzymes: amylase in saliva and pancreas breaks down carbs, pepsin in stomach for proteins, lipase from pancreas for fats. Bile from liver emulsifies fats. pH in stomach is 1.5-3.5, important for enzyme activation and killing bacteria. The large intestine absorbs water, forms feces. Appendix's role in immunity. Probiotics maintain gut microbiome. Digestive processes experiments: testing for nutrients, variables in experiments. Review questions cover definitions, matching teeth to functions, enzyme roles, effects of temperature on enzymes, pH importance, peristalsis, bile functions, villi structure, relationships between organs. Case studies on vitamin deficiencies, gut-brain axis, animal digestive systems comparisons. The research studies on probiotics and stress affecting gut health. Finally, detailed explanations of biomolecules: carbs, proteins, lipids, nucleic acids. Their monomers, functions, sources. I need to compile all this without missing specifics. Make sure to include each organ's role, enzymes, nutrient tests, processes like peristalsis, and diagrams if possible. Also, cover the experiments, variables, and case studies. Maybe structure it by checklist sections to follow the original document's flow. Year 8 Science: Digestion Comprehensive Notes (Based on Checklists, Notes, PPTs, and Test Answers) 1. Body Systems & Digestive System Overview Key Systems in Multicellular Organisms: Digestive System: Breaks down food, absorbs nutrients, removes waste. Circulatory System: Transports oxygen, nutrients, hormones; removes CO₂ (heart, blood vessels). Respiratory System: Exchanges oxygen and CO₂ (lungs, airways). Other Systems: Nervous, Excretory, Musculoskeletal, Reproductive. Digestive Processes: Ingestion: Taking in food through the mouth. Mechanical Digestion: Physical breakdown (e.g., chewing). Chemical Digestion: Enzymatic breakdown (e.g., amylase, pepsin). Absorption: Nutrients enter bloodstream (small intestine). Egestion: Elimination of undigested waste (faeces). Why Digestion is Essential for Survival: Provides energy (glucose), building blocks (amino acids), and removes harmful waste. Without digestion, nutrients cannot be absorbed, leading to starvation and toxin buildup. 2. Mechanical vs. Chemical D for the above information, remove all redudant and re-occuring inofrmation and divide the information into sections.

Thought for 0 seconds