In order to function, the cells of the brain need large amounts of energy. Any reduction in the
function of these cells can have serious consequences for the body. For example, a loss of
oxygen supply to the brain can cause unconsciousness within 5–10 seconds.
Which of the following statements are true?
1 Neurons in the brain are capable of relying on anaerobic respiration for long
periods of time.
2 The homeostatic systems of the body will constantly have to work to resist
temperature increases in the brain.
3 An overdose of insulin in the body could produce a serious loss of brain function,
such as inducing a coma.
4 During normal functioning of neurons in the brain, high levels of carbon dioxide
could be produced.

Answer:

Statement 1 is not true. In the opening paragraph you are told that oxygen supply is essential for
neurons in the brain to function for more than 5 – 10 seconds. Anaerobic respiration cannot,
therefore, be used for prolonged periods of time.
Statement 2 is true because a by-product of aerobic respiration is heat so as respiration occurs, the
body will have to work to counteract the corresponding increase in temperature.
Statement 3 is true. Too much insulin will lower body glucose levels and this could prevent sufficient
respiration from occurring, resulting in a lack of energy and therefore brain function.
Statement 4 is true because carbon dioxide is produced during aerobic respiration.
The answer is G