AQA Biology GCSE Topic 2: Organisation

Flashcards summarizing key concepts from AQA Biology GCSE Topic 2: Organisation.

What do cells make up?

All living things.

What is a tissue?

A group of specialised cells with a similar structure and function.

What forms an organ?

A number of different tissues working together to perform a specific function.

What organ is part of the digestive system?

The stomach.

What do glands in the digestive system produce?

Digestive juices containing enzymes.

What is the function of the stomach in digestion?

Produces hydrochloric acid to kill bacteria and provide the optimum pH for enzyme action.

What does the small intestine do?

Absorbs soluble molecules into the blood.

What does the liver produce?

Bile, which helps with the digestion of lipids.

What do large intestines do?

Absorb water from undigested food to produce faeces.

What are enzymes?

Biological catalysts that increase the rate of reaction without being used up.

What is the Lock and Key Hypothesis?

The shape of the substrate is complementary to the shape of the active site, forming an enzyme-substrate complex.

What happens to enzymes at high temperatures?

They become denatured and can no longer work.

What is the optimum temperature for most enzymes?

Around 37 degrees Celsius.

What is an example of a carbohydrase?

Amylase, which breaks down starch into maltose.

What do proteases convert?

Proteins into amino acids.

What do lipases convert?

Lipids into fatty acids and glycerol.

What is the blood vessel that carries blood away from the heart?

Arteries.

What is the main function of veins?

Carry blood towards the heart.

What are capillaries special for?

Allow substances to move between blood and cells.

What happens in the alveoli?

Gas exchange occurs, where oxygen and carbon dioxide are exchanged.

What are the components of blood?

Plasma, red blood cells, white blood cells, and platelets.

What is the role of platelets?

Help form blood clots at the site of a wound.

What is coronary heart disease?

When coronary arteries become blocked with fatty material.

What is the purpose of a stent?

Keeps arteries open to allow blood flow.

What do statins do?

Decrease LDL cholesterol levels to reduce risk of heart disease.

What is the difference between communicable and non-communicable diseases?

Communicable diseases are infectious, non-communicable diseases are not.

What is health defined as?

A state of physical, mental, and social well-being, not merely the absence of disease.

What is type 2 diabetes associated with?

Obesity affects the body's metabolism and sugar uptake.

What factors affect health?

Diet, stress, and life situations.

What is the role of xylem in plants?

Transport water and minerals from roots to other parts of the plant.

What does phloem do?

Translocate food substances throughout the plant.

What is transpiration?

The loss of water vapour from the leaves and stems of a plant.

How do guard cells function?

They open and close stomata based on water availability.

What does an increase in temperature do to transpiration?

It increases the rate of transpiration.

Describe how the structure of arteries, veins, and capillaries are related to their functions

• Arteries have thick muscular and elastic walls to withstand and maintain high pressure.

• Small lumen to help maintain pressure.

• Veins have thinner walls because blood is at lower pressure.

• Large lumen to help blood flow.

• Valves in veins prevent backflow.

• Capillaries have walls one cell thick to allow fast diffusion of substances like oxygen and glucose.

Explain why heart rate and breathing rate increase during exercise

• Muscles need more energy for contraction.

• Increased rate of aerobic respiration.

• More oxygen and glucose needed.

• Heart rate increases to pump more blood (carrying oxygen and glucose) to muscles.

• Breathing rate and breath volume increase to bring more oxygen into blood and remove carbon dioxide faster.

• Helps maintain a concentration gradient for diffusion of gases.

Describe what happens to the blood flow through the heart when a person starts exercising and explain why these changes happen

• Heart contracts faster and more forcefully.

• Increased blood flow through pulmonary circulation (lungs) to pick up more oxygen.

• Increased blood flow through systemic circulation (body) to deliver more oxygen and glucose to muscles.

• Higher cardiac output (amount of blood pumped per minute).

• Needed to meet increased demand for respiration.

• Reduces risk of anaerobic respiration and lactic acid build-up.

Explain the process of oxygen debt and how the body deals with it after exercise

• During intense exercise, anaerobic respiration occurs because oxygen supply is insufficient.

• Anaerobic respiration produces lactic acid.

• Oxygen debt: extra oxygen needed after exercise to break down lactic acid into carbon dioxide and water.

• Heart rate remains high after exercise to pump oxygenated blood around.

• Breathing rate remains high to supply oxygen to muscles.

• Liver also helps break down lactic acid.

Compare aerobic and anaerobic respiration during exercise

• Aerobic respiration requires oxygen; anaerobic does not.

• Aerobic releases more energy (efficient); anaerobic releases much less.

• Aerobic respiration produces carbon dioxide and water; anaerobic produces lactic acid.

• Anaerobic occurs when exercise is very intense.

• Lactic acid causes muscle fatigue and requires oxygen debt to be removed.

• Aerobic respiration is the normal method during moderate exercise.

Evaluate the advantages and disadvantages of anaerobic respiration during intense exercise

• Advantage: Can continue producing energy when oxygen is in short supply.

• Advantage: Allows muscles to keep working for a short time.

• Disadvantage: Produces lactic acid, causing fatigue and pain.

• Disadvantage: Less energy released compared to aerobic respiration.

• Disadvantage: Requires oxygen debt to be repaid afterwards.

• Overall: Anaerobic respiration is useful short-term but unsustainable long-term.

Describe two ways in which red blood cells are adapted to their function

• Biconcave shape increases surface area for oxygen diffusion.

• No nucleus to allow more room for haemoglobin.

• Contain haemoglobin to carry oxygen.

State three substances transported by the plasma in blood

• Carbon dioxide.

• Glucose.

• Urea (also accept hormones, antibodies)

Suggest three ways the body responds to increase oxygen supply during exercise

• Increased heart rate.

• Increased breathing rate.

• Blood vessels dilate to muscles. This enhances oxygen delivery to tissues and improves aerobic respiration efficiency.

Give three differences between arteries and veins

• arteries have thick walls; veins have thinner walls.

• Arteries have small lumen; veins have larger lumen.

• Veins have valves; arteries do not.

Describe how the structure of a capillary helps it perform its function

• Walls one cell thick for quick diffusion.

• Very small diameter (short distance to body cells).

• Permeable walls allow exchange of substances.

• Network of capillaries gives large surface area.

Explain why heart rate remains high after intense exercise

• o deliver extra oxygen to muscles.

• To repay the oxygen debt.

• To break down lactic acid.

• To remove carbon dioxide quickly.

Describe two differences between aerobic and anaerobic respiration and explain why anaerobic respiration occurs

• Aerobic uses oxygen; anaerobic does not.

• Aerobic releases more energy.

• Anaerobic occurs when oxygen supply cannot meet energy demand during intense exercise.

Explain how valves in veins help maintain blood flow

• Blood in veins under low pressure.

• Valves prevent backflow of blood.

• Blood flows in one direction toward the heart.

• Helps return blood to the heart efficiently.