Question 1: During exercise, the body's demand for energy increases, leading to changes in the respiration rate and heart rate to supply more oxygen to the muscles. These responses are crucial for maintaining activity and preventing fatigue.

Answer: The body increases respiration rate and heart rate to deliver more oxygen and remove waste products like carbon dioxide during exercise.

Question 2: Define aerobic respiration and explain its role during exercise.

Answer: Aerobic respiration is the process of releasing energy from glucose using oxygen, providing a sustained energy supply during exercise.

Question 3: What are the main differences between aerobic and anaerobic respiration?

Answer: Aerobic respiration uses oxygen and produces more energy, carbon dioxide, and water, while anaerobic respiration occurs without oxygen, producing less energy and lactic acid.

Question 4: Explain why muscles produce lactic acid during vigorous exercise.

Answer: Muscles produce lactic acid during vigorous exercise because, in the absence of sufficient oxygen, they switch to anaerobic respiration to generate energy.

Question 5: Describe two physiological changes that occur in the body during exercise to meet increased energy demands.

Answer: Increase in respiration rate and heart rate.

Question 6: Calculate the amount of energy (in joules) released from the complete oxidation of 1 gram of glucose, given that the energy released per mole is approximately 2870 kJ. (Atomic mass of glucose = 180 g/mol)

Answer: Energy (J) = (mass of glucose in grams / molar mass) × energy per mole = (1 g / 180 g) × 2870 kJ × 1000 J / 1 kJ = (0.00556 mol) × 2870 kJ × 1000 J / 1 kJ ≈ 15,950 J

Question 7: Identify three variables that could be controlled in an experiment to measure the effect of exercise intensity on respiration rate.

Answer: Exercise intensity, duration of exercise, and environmental temperature.

Question 8: Describe a simple experiment to investigate how exercise affects breathing rate. Include the variables involved and safety precautions.

Answer: Students could measure their resting breathing rate, then perform a set amount of vigorous exercise (e.g., jumping jacks), and measure their breathing rate immediately after. Variables include exercise intensity and duration. Safety precautions include warming up beforehand, avoiding overexertion, and ensuring a safe environment free from obstacles.

Question 9: Data shows that after exercise, a person's breathing rate increases from 12 breaths per minute to 24 breaths per minute. Explain the physiological reason for this change.

Answer: The increase in breathing rate helps supply more oxygen to muscles and remove carbon dioxide produced during increased metabolic activity.

Question 10: In what ways does regular physical activity improve the efficiency of the respiratory system?

Answer: Regular activity increases lung capacity, strengthens respiratory muscles, and improves oxygen uptake efficiency.

Question 11: Explain how the body’s energy systems adapt during sustained exercise over a long period.

Answer: During sustained exercise, the body increases the efficiency of aerobic respiration, develops more mitochondria in muscle cells, improves oxygen delivery via cardiovascular adaptations, and enhances fat utilisation for energy.