Topic 2: Organisation & Digestive System
Call Kai
Learn
Practice Test
Spaced Repetition
Match
Flashcards
Knowt Play1/67
There's no tags or description
Looks like no tags are added yet.
68 Terms
What is a tissue?
A group of cells with similar structure and function working together.
What is an organ?
An aggregation of tissues performing specific functions.
What is an organ system?
A group of organs working together to perform a specific body function.
What is peristalsis?
Waves of muscle contractions in the walls of the alimentary canal (like the oesophagus and gut) that push food along.
What is an enzyme?
A biological catalyst made of protein that speeds up chemical reactions without being used up.
What is an active site?
The specific region on an enzyme where the substrate binds to undergo a reaction.
Explain the lock and key model of enzyme action.
The active site has a specific 3D shape complementary to a specific substrate; they fit together to form an enzyme-substrate complex.
What happens when an enzyme denatures?
High temperatures or extreme pH break structural bonds, altering active site shape so substrate no longer fits.
How does temperature affect enzyme activity?
Activity increases up to optimum temperature due to higher kinetic energy. Above optimum, bonds break and enzyme denatures.
How does pH affect enzyme activity?
Every enzyme has an optimum pH. Moving above or below alters charges and breaks active site bonds, causing denaturation.
What is the function of digestive enzymes?
To break down large, insoluble food molecules into small, soluble molecules for absorption into the blood.
What are the main organs of the digestive system and their specific roles?
Mouth: Chews food and secretes amylase. 2. Oesophagus: Transports food via peristalsis. 3. Stomach: Churns food, secretes HCl and protease (pepsin). 4. Liver/Gallbladder: Produces and stores bile. 5. Pancreas: Secretes amylase, protease, lipase. 6. Small Intestine: Digests food and absorbs nutrients. 7. Large Intestine: Absorbs water to form faeces.
Where is amylase produced and what does it do?
Produced in salivary glands, pancreas, small intestine. Breaks starch down into simple sugars (maltose).
Where are proteases produced and what do they do?
Produced in stomach (pepsin), pancreas, small intestine. Break down proteins into amino acids.
Where are lipases produced and what do they do?
Produced in pancreas and small intestine. Break down lipids into fatty acids and glycerol.
What is the difference between physical and chemical digestion in bile?
Bile performs physical digestion by emulsifying large fat droplets into tiny droplets (increasing surface area), whereas enzymes perform chemical digestion by breaking chemical bonds.
Where is bile produced, stored, and what are its two main functions?
Produced in liver, stored in gallbladder. 1. Neutralises stomach acid (HCl) in small intestine to create optimum alkaline pH. 2. Emulsifies fats into small droplets to increase surface area for lipase.
What are the key steps in Required Practical 3 (Food Tests)?
Starch: Add Iodine -> Blue-black if positive. 2. Glucose: Add Benedict's, heat at ~75°C for 5 mins -> Green/yellow/brick-red. 3. Protein: Add Biuret -> Purple/lilac. 4. Lipids: Add Ethanol, shake, pour into water -> Cloudy white emulsion.
What are the steps and variables for Required Practical 4 (Effect of pH on Amylase Activity)?
Put iodine drops into every well of a spot tile. 2. Mix amylase, starch, and buffer solution of specific pH in 30°C water bath. 3. Every 30 seconds drop mixture into a well. 4. Record time when iodine stays orange/brown. Independent variable: pH level. Dependent variable: Time taken for starch to disappear.
How do you calculate the rate of an enzyme reaction?
Rate = 1000 / time taken (s) OR Rate = Amount of product formed / time taken.
What is the double circulatory system and why is it important?
Blood passes through the heart twice for every complete circuit. Allows blood to be pumped to the body under much higher pressure.
Trace the flow of blood through the heart?
Vena cava -> Right atrium -> Right ventricle -> Pulmonary artery -> Lungs -> Pulmonary vein -> Left atrium -> Left ventricle -> Aorta -> Body.
Why is the wall of the left ventricle thicker than the right ventricle?
Left ventricle needs to generate higher pressure to pump blood all around the body, whereas right ventricle only pumps to lungs.
What is the pacemaker of the heart?
A group of specialised cells in the right atrium wall that control natural resting heart rate using electrical impulses.
How is an irregular heart rate treated?
With an artificial pacemaker—an electronic device implanted under skin connected to heart via wires.
How are arteries adapted to their function?
Carry blood away from heart under high pressure. 2. Thick muscular walls with elastic fibres to stretch and recoil. 3. Narrow lumen.
How are veins adapted to their function?
Carry blood towards heart under low pressure. 2. Thin walls and wide lumen. 3. Contain valves to prevent backflow.
How are capillaries adapted to their function?
Thin walls (one cell thick) for short diffusion pathway. 2. Permeable walls allowing exchange.
What are the four components of blood and their functions?
Red blood cells: Transport oxygen via haemoglobin. 2. White blood cells: Defend against pathogens. 3. Platelets: Cell fragments for blood clotting. 4. Plasma: Liquid carrying dissolved nutrients, CO2, urea, hormones.
How are red blood cells adapted for oxygen transport?
Biconcave disc shape increases SA:V ratio. 2. Contain haemoglobin. 3. No nucleus for maximum haemoglobin space.
Give three examples of interactions between different types of diseases?
Immune defects make a person susceptible to infectious diseases. 2. Viruses in cells can trigger cancer (HPV -> cervical cancer). 3. Immune reactions triggered by pathogens can provoke allergies like asthma.
How are alveoli in the lungs adapted for gas exchange?
Millions of tiny alveoli provide a huge surface area. 2. Walls are one cell thick for a very short diffusion distance. 3. Moist lining allows gases to dissolve easily. 4. Rich capillary network maintains a steep concentration gradient by constantly carrying oxygen away and bringing carbon dioxide.
What four factors increase rate of transpiration?
1 light intensity. 2. temperature. 3. air movement/wind. 4. humidity.
How do guard cells control stomata?
In high light/water, they absorb water by osmosis, become turgid and bow outward to open. In dark/drought, they lose water, become flaccid and close.
Closing protects the plant by preventing excessive water loss and dehydration during periods of drought or darkness.
Opening protects the plant's survival by allowing it to take in necessary gases for photosynthesis when water and light are available.
What is the function of the liver in digestion and excretion?
Produces bile to emulsify fats and neutralise stomach acid. 2. Deaminates excess amino acids into toxic ammonia, then converts it into urea for excretion by kidneys. 3. Breaks down excess toxins and recycles red blood cells.