Bioenergetics: Exercise

Question 1

Why does more respiration need to be done during exercise?

Answer 1

More energy is required due to:
- more muscular contraction being done
- heart rate increasing
- breathing rate increasing

Question 2

Why does heart rate increase during exercise? (2)

Answer 2

• to increase blood flowing to muscles which provides them with more oxygen and more glucose and removes CO₂ and lactic acid more quickly (from the muscles

Question 3

Why does breathing rate increase during exercise? (2)

Answer 3

• to get more oxygen into the blood (1) for use in respiration (1)
• to remove more CO₂ (1) produced in respiration (1)

Question 4

How is lactic acid transported away from the muscles?

Answer 4

• blood flow through muscles transports lactic acid to the liver
• here it is oxidised back to glucose

Question 5

Explain why a person with a leaking heart valve has difficulty exercising. (4 marks)

Answer 5

• backflow can occur
• so less blood will be able to be pumped to the body
• less O₂ will be supplied to muscles
• so less aerobic respiration occurs
• less energy is released
• less muscle contraction
• anaerobic respiration takes place, causing oxygen debt and the build up of lactic acid
• build up of lactic acid causes muscle fatigue
• less CO₂ is removed from blood