orgnisation B2

this is for my GCSE revision I study higher tier triple science aiming fro a grade 8

Protease

Proteases are a class of digestive enzymes responsible for breaking down proteins into smaller peptides and ultimately into amino acids, facilitating their absorption into the bloodstream.

The digestion of proteins

Proteins are primarily digested in the stomach by an enzyme called pepsin, and further digested in the small intestine by various proteases, enabling the body to utilize the protein from food.

Production sites of proteases

Proteases are produced in multiple parts of the body including the stomach, pancreas, and small intestine, where they play a crucial role in protein digestion.

Structure of an enzyme

Enzymes consist of long chains of amino acids that are intricately folded into specific three-dimensional shapes. Each enzyme features a uniquely shaped active site, which is complementary to the specific substrate it binds to, allowing for precise catalysis.

Lock and key theory

The lock and key theory is a model of enzyme action that posits that the shape of an enzyme's active site is specifically designed to fit a particular substrate, akin to a key fitting into a lock.

Enzyme specificity

Enzymes and their active sites are characterized by highly specific shapes. This specificity ensures that only certain substrates can bind, leading to the formation of enzyme-substrate complexes that enable the enzyme to catalyze a particular reaction.

The 'lock and key' model

The 'lock and key' model simplifies enzyme functionality by comparing the active site of the enzyme to a lock that only a specific key (substrate) can unlock, emphasizing the importance of shape in enzyme-substrate interactions.

Amylase

Amylase is a key carbohydrase enzyme that catalyzes the conversion of starch into maltose, a disaccharide composed of two glucose molecules, thereby playing an essential role in carbohydrate digestion.

Amylase digestion location

Amylase functions to digest starch in both the mouth and the small intestine, where it is secreted by the salivary glands, pancreas, and small intestine.

Bile

Bile is a digestive fluid produced by the liver, stored in the gall bladder, and released into the small intestine. It serves multiple functions, primarily aiding in the emulsification of fats and the neutralization of stomach acid.

Bile's dual function

Bile neutralizes hydrochloric acid from the stomach, creating an optimal pH for enzymes in the small intestine to function efficiently. Additionally, bile emulsifies fats, breaking them into smaller droplets for enhanced digestion by lipase enzymes.

Lipase

Lipases are specialized digestive enzymes that catalyze the breakdown of lipid molecules into glycerol and fatty acids, primarily occurring in the small intestine. These enzymes are produced in both the pancreas and small intestine.

Overview of digestion

Digestion begins in the mouth, where food undergoes mechanical breakdown by teeth and is mixed with saliva containing amylase to initiate starch digestion. This food then travels through the esophagus to the stomach.

Function of the stomach in digestion

The stomach mechanically churns food and chemically breaks down proteins using pepsin, functioning effectively in acidic conditions due to hydrochloric acid, which also helps to eliminate most foodborne bacteria.

Processing food in the small intestine

In the small intestine, bile and various digestive enzymes are released. Bile neutralizes stomach acid, while enzymes breakdown starch, proteins, and lipids into smaller absorbable units.

Nutrient absorption

Once food molecules are broken down into smaller components, they can be efficiently absorbed through specialized intestinal cells into the bloodstream.

Large intestine role

The large intestine absorbs excess water from the remaining undigested food and stores waste in the rectum, which is eventually excreted through the anus.

Digestive system's purpose

The digestive system's primary function is to break down food into smaller, absorbable units that enter the bloodstream for transportation to body cells.

Lungs' primary function

The primary function of the lungs is to facilitate the exchange of gases; they intake oxygen from the atmosphere for use in cellular respiration and expel carbon dioxide produced by the body’s metabolic processes.

Adaptive features of alveoli

Alveoli are tiny air sac structures in the lungs that provide a vast surface area, are lined with moisture to help dissolve gases, have thin walls for short diffusion distances, and possess a rich blood supply to maintain concentration gradients for gas exchange.

Respiratory system overview

Air enters the body through the mouth or nose, travels down the trachea, which divides into bronchi leading into each lung, and then branches into bronchioles that terminate in alveoli, which are the sites of gas exchange.

Location and support of lungs

The lungs are situated in the thoracic cavity and are protected by the rib cage. They are further encased in pleural membranes which aid in the mechanics of breathing, facilitated by the diaphragm and intercostal muscles.

Inhalation process

During inhalation, the external intercostal muscles contract, lifting the rib cage up and out, while the diaphragm contracts and flattens, resulting in decreased pressure and increased volume in the thoracic cavity, drawing air into the lungs.

Exhalation process

During exhalation, the external intercostal muscles relax, causing the rib cage to lower, while the diaphragm relaxes, increasing thoracic pressure and expelling air from the lungs.

Gas exchange in alveoli

Deoxygenated blood reaches the lungs where oxygen from alveolar air diffuses into the blood, while carbon dioxide from the blood diffuses into the alveoli to be exhaled.

Double circulatory system explanation

Humans possess a double circulatory system consisting of two interconnected loops: one loop carries deoxygenated blood from the heart to the lungs for oxygenation, while the second loop distributes oxygenated blood to the rest of the body.

Arterial function

Arteries transport blood away from the heart to the body's tissues and are characterized by thick elastic walls and a narrow lumen to withstand high pressure generated by the heart.

Veins function

Veins return deoxygenated blood back to the heart under lower pressure, necessitating thinner walls, larger lumens, and valves that prevent backflow, ensuring continuous flow in the correct direction.

Capillaries function

Capillaries are microscopic blood vessels that connect arteries and veins, facilitating the exchange of oxygen, glucose, waste products, and other substances between blood and surrounding tissues due to their permeable one-cell-thick walls.

Heart structure and function

The heart features a right and left side, divided by the septum, with each side consisting of an atrium and a ventricle, ensuring the directional flow of blood: deoxygenated blood to the lungs and oxygenated blood to the body.

Flow of blood through the heart

Deoxygenated blood enters the right atrium through the vena cava, is pushed to the right ventricle, and then pumped through the pulmonary artery to the lungs. Conversely, oxygenated blood from the lungs enters the left atrium, moves to the left ventricle, and is sent through the aorta to supply the body.

Red blood cells role

Red blood cells are specialized cells responsible for transporting oxygen from the lungs to body tissues for aerobic respiration. They contain hemoglobin, allowing efficient oxygen binding and release at the cellular level.

Adaptations of red blood cells

Red blood cells are uniquely adapted for gas transport: their biconcave shape increases surface area for diffusion, their small size allows passage through capillaries, they lack a nucleus to maximize hemoglobin content, and they are abundant in hemoglobin to efficiently carry oxygen.

Role of white blood cells

White blood cells form a critical component of the immune system, tasked with identifying and eliminating pathogens. They contain a nucleus and are categorized into different types based on their specific immune responses.

Types of white blood cells

Two main types of white blood cells include phagocytes, which engulf and digest pathogens, and lymphocytes, which identify pathogens and produce antibodies that attach to them, enhancing removal by phagocytes.

Plasma in blood

Plasma is a yellowish liquid component of blood that transports various substances, including red blood cells, white blood cells, platelets, nutrients (like glucose and amino acids), waste products (like carbon dioxide and urea), and hormones.

Platelets' function

Platelets are cell fragments crucial for blood clotting, preventing excessive bleeding when wounds occur by forming clots that seal damaged blood vessels and protect against pathogen entry.

Coronary heart disease (CHD) overview

Coronary heart disease occurs when the coronary arteries become narrowed or blocked due to fatty deposits (atherosclerosis), restricting blood flow and oxygen supply to the heart muscle, potentially leading to a heart attack.

Function of coronary arteries

The coronary arteries supply oxygenated blood to the heart muscle itself, essential for its energy needs and continuous contraction to maintain blood circulation.

Stents in coronary artery treatment

Stents are tiny mesh tubes inserted into coronary arteries to keep them open, allowing blood flow to the heart muscle. This reduces the risk of heart attacks and has a relatively short recovery time, although there are risks of complications such as infections.

Statins function

Statins are cholesterol-lowering drugs that reduce 'bad' LDL cholesterol levels in the blood, helping to prevent the formation of fatty plaques in blood vessels, thereby reducing the risk of cardiovascular diseases.

Side effects of statins

Statins can cause side effects including headaches, joint pain, and potential kidney issues. They require consistent usage for effectiveness and may not produce immediate results.

Faulty heart valves issues

Faulty heart valves can either leak, allowing backward flow of blood, or become stiff and reduced in function, necessitating surgical intervention such as replacement with biological or mechanical valves.

Heart failure treatment

Patients with severe heart failure may need a heart transplant or artificial heart. Organ transplants are high-demand procedures often resulting in waiting lists, while artificial hearts allow for temporary management.

Artificial hearts comparison

Artificial hearts are designed to replace biological functions temporarily, posing less risk of rejection. However, they may have limited efficiency, increased wear, and require anticoagulant medications to prevent blood clots.

Definition of health

Health encompasses a holistic state of physical and mental well-being, influenced by multiple factors including diseases, lifestyle choices, stress, and access to necessary resources.

Disease impact on health

Diseases can be either communicable or non-communicable, and they represent a primary cause of ill health which can significantly affect quality of life.

Importance of diet

A balanced diet is essential for providing necessary nutrients to maintain physical and mental health, while poor nutrition increases susceptibility to various health issues.

Stress and health

Persistent stress can have detrimental effects on health, leading to issues such as cardiovascular diseases and mental health conditions.

Life situation and health

Access to healthcare, clean water, and nutrition significantly impacts health outcomes. For instance, availability of preventive measures like vaccines can reduce the incidence of diseases.

Non-communicable diseases explained

Non-communicable diseases are those that cannot be transmitted from one person to another, typically long-term and progressively worsening, such as diabetes, heart diseases, and certain cancers.

Costs of non-communicable diseases

The human and financial burdens of non-communicable diseases include decreased quality of life, emotional distress for families, and substantial costs associated with healthcare and necessary lifestyle adjustments.

Risk factor definition

Risk factors are characteristics or behaviors that increase the likelihood of developing a particular illness or disease, influenced by lifestyle, environment, and genetic predisposition.

Correlation vs causation in health

Establishing that a risk factor causes a disease requires scientific investigation to understand the mechanisms behind correlations, as correlations do not imply causation.

Established risk factors for diseases

Research has shown that lifestyle factors such as smoking, poor diet, and insufficient exercise raise the risk for conditions like cardiovascular diseases and diabetes.

Obesity and diabetes

Obesity is a significant risk factor for developing type 2 diabetes due to its influence on insulin resistance and related metabolic processes.

Alcohol consumption risks

High alcohol intake is linked to liver diseases and neurological impairments, highlighting the need for moderation and awareness of alcohol's effects.

Smoking and lung health

Tobacco use significantly raises the likelihood of developing lung disease and lung cancer, underscoring the importance of cessation programs.

Pregnancy and substance exposure

Smoking and alcohol consumption during pregnancy can adversely affect fetal development, leading to various health complications.

Carcinogenic exposure risks

Exposure to carcinogens, including radiation and certain chemicals, heightens the risk of developing cancer, emphasizing the importance of protective measures.

Complex causes of diseases

Multiple factors often contribute to the development of diseases, making it essential to consider a range of risk factors rather than targeting isolated issues.

Incidence of diseases and geography

The occurrence of non-communicable diseases varies globally due to differing lifestyles, dietary habits, and healthcare access, highlighting disparities between developed and developing regions.

Purpose of sampling in research

Sampling allows researchers to study population health trends without examining every individual, utilizing medical data or surveys to explore potential risk factors.

Representativeness in sampling

To ensure validity, samples must accurately represent the population being studied, incorporating diverse demographics and random selection methods.

Other factors in health studies

Factors such as age, gender, and lifestyle differences must be accounted for in studies, allowing for targeted analysis and improved comparisons.

Temporal sampling practices

Data may be collected periodically to track health trends and risk factors over time, supporting ongoing research and intervention strategies.

Principles of biological organization

Cells serve as the fundamental building blocks of living organisms, which group together to form tissues, organs, and ultimately, organ systems that work in concert within an organism.

Definition of tissue

A tissue is a collection of similar cells that work together to perform specific functions, contributing to the overall functioning of an organ.

Organ structure and function

Organs consist of different types of tissues organized to perform complex functions, each organ contributing to the body's overall physiology.

Organ systems and organisms

Organ systems are groupings of organs that collaborate to achieve specific physiological goals, collectively constituting a living organism.

Tumor growth and cellular changes

Tumor growth arises when genetic alterations disrupt normal cell division controls, leading to uncontrolled proliferation and the formation of masses within tissues.

Cancer definition

Cancer is characterized by uncontrolled cell division, resulting in malignant growths that can invade neighboring tissues and disrupt normal organ function.

Malignant tumors

Malignant tumors are cancerous formations that can metastasize, spreading to other regions of the body through blood and lymphatic systems, ultimately leading to secondary cancerous developments.

Benign tumors

Benign tumors remain localized, enclosed within a membrane, typically posing little threat to health, as they do not invade surrounding tissues.

Cancer risk factors

Factors contributing to cancer risk include obesity, which has been linked to several types of cancer, and exposure to known carcinogens like tobacco smoke.

Smoking's cancer connections

Smoking is a well-established risk factor for various cancers, including lung cancer, and increases susceptibility to multiple other types.

UV exposure and skin cancer

Exposure to ultraviolet radiation, either from sunlight or artificial sources, significantly raises the risk of developing skin cancer.

Viral triggers of cancer

Certain viral infections, such as those from human papillomavirus (HPV) and hepatitis viruses, can initiate cancer formation by altering cellular functions.

Genetic predisposition to cancer

Some individuals inherit faulty genes, like BRCA mutations, which increase their chances of developing specific cancers such as breast and ovarian cancer.

Reducing cancer risk

While anyone can develop cancer, mitigating risks through lifestyle choices such as a balanced diet, regular exercise, refraining from smoking, and protecting against sun exposure can lower occurrence rates.

Plant leaves structure and function

Leaves are specialized plant organs responsible primarily for photosynthesis and gas exchange, structured with tissues optimized for these functions.

Epidermis and cuticle role

Epidermal tissues on the leaf's surface, covered by a waxy cuticle, reduce water loss by evaporation while allowing sunlight to reach photosynthetic cells.

Palisade mesophyll adaptation

The palisade mesophyll is a layer rich in chloroplasts, located near the upper leaf surface where it captures substantial light for photosynthesis.

Spongy mesophyll characteristics

The spongy mesophyll contains air spaces to facilitate gas diffusion, ensuring that carbon dioxide and oxygen can reach photosynthesizing cells effectively.

Vascular tissue's function in leaves

The leaf's xylem and phloem tissues serve to transport water, nutrients, and sugars, respectively, contributed by photosynthesis and absorbed from the soil.

Meristem definition

Meristematic tissue found at plant shoot and root tips contains stem cells that enable growth through the generation of new plant cells.

Phloem transport process

Phloem consists of living cells that facilitate the transport of food substances like sugars throughout the plant, playing a crucial role in nutrient distribution.

Phloem cell structure

Phloem cells are elongated and interconnected with sieve plates, allowing the flow of cell sap while also having minimal internal structures for efficient transport.

Bidirectional movement in phloem

In the phloem, substances can move in both directions, efficiently delivering nutrients to non-photosynthesizing areas and storage sites.

Translocation in plants

The process of translocation describes the movement of nutrients, particularly sugars produced during photosynthesis, from leaves to other parts of the plant via phloem.

Xylem's role in transport

Xylem cells are specialized for the upward transport of water and minerals from roots to stems and leaves, operating as hollow tubes without cytoplasm.

Xylem cells and function

Xylem cells are lignified and dead at maturity, forming a continuous vessel that efficiently conducts water via the transpiration stream.

Transpiration process

Transpiration is the process by which water evaporates from leaf surfaces, creating a negative pressure that draws water up from roots through the xylem.

Mechanics of water uptake

In transpiration, water loss from leaves leads to increased water uptake from the soil, with root hair cells adapted for efficient absorption of both water and minerals.

Stomata and guard cell function

Stomata are pores on leaf surfaces that allow gas exchange, with guard cells regulating their opening and closing based on environmental moisture and light.

Factors affecting transpiration rate

Transpiration rates increase with higher temperature, reduced humidity (steeper concentration gradients), increased air movement, and light intensity due to guard cell turgidity.

Benedict's test for reducing sugars

Benedict's test determines the presence of reducing sugars by adding Benedict's solution to a food sample and heating it, observing color changes to indicate sugar content.

Test for lipids (Ethanol test)

The presence of lipids is tested using ethanol and distilled water; if lipids are present, a cloudy emulsion forms, indicating their presence.

Iodine test for starch

The presence of starch in a food sample is tested by adding iodine solution; a color shift from brown-orange to blue-black indicates starch.

Biuret test for proteins

The Biuret test uses biuret reagents to identify proteins; a blue to purple color change indicates the presence of protein within the sample.