3.2 Read the extract below on cellular respiration.

Aerobic and anaerobic respiration are used to supply energy during exercise. During certain types of exercise, for example, athletic events such as 100m, 200m, 1500m and 3000m the muscles are unable to obtain sufficient oxygen for the removal of large quantities of lactic acid from the muscle cells. When sprinting an athlete cannot possibly inhale more than the fraction of oxygen required, and the body goes into an "oxygen debt". "Oxygen debt" can be defined as the extra oxygen needed to normalize the process after strenuous exercise. This debt can only be repaired by rapid breathing after the sprint ended.

[Adapted from: Neuroscience & Bio behavioural Review, 2023.]

3.2.1 Name TWO end products of aerobic respiration in muscle cells.
3.2.2 In which athletic event does athletes mostly experience the effect of anaerobic respiration in their bodies?
3.2.3 Explain the impact of the item named in QUESTION 3.2.2 on the body.
3.2.4 What conclusion can be made with regards to anaerobic respiration and glucose?

Aerobic respiration occurs in the presence of oxygen and is a highly efficient way of producing energy in the form of ATP (adenosine triphosphate). The two main end products of aerobic respiration in muscle cells are:

Carbon dioxide (CO2)
Water (H2O)

These products are released after glucose is fully oxidized in a series of reactions.

3.2.2 In which athletic event do athletes mostly experience the effect of anaerobic respiration in their bodies?

Anaerobic respiration, which does not require oxygen, typically becomes significant in short, intense bursts of exercise where oxygen demand exceeds supply. Athletes are most likely to experience the effects of anaerobic respiration during events such as the 100m and 200m sprints.

3.2.3 Explain the impact of the item named in QUESTION 3.2.2 on the body.

During short sprints like the 100m or 200m, an athlete's muscles might rely heavily on anaerobic respiration due to rapid exertion and limited oxygen supply. This process results in the accumulation of lactic acid as a by-product. The build-up of lactic acid can lead to muscle fatigue and discomfort, known as "the burn." After the event, the body needs to process this lactic acid, typically by converting it back to pyruvate during recovery, which requires additional oxygen, known as the "oxygen debt."

3.2.4 What conclusion can be made regarding anaerobic respiration and glucose?

From the discussion, we can conclude that anaerobic respiration is a less efficient process than aerobic respiration in terms of ATP production per glucose molecule. It results in the partial breakdown of glucose and leads to quicker onset of muscle fatigue due to lactic acid production. This pathway becomes crucial during exertions when oxygen supply is insufficient to meet energetic demands quickly.