Summative Practice Chapter 7 – Question 1 – 5 (Form 4 Biology Textbook Exercise and Answer)

Question 1:
What are the uses of alcohol fermentation products?

Ethanol is used in the production of beer and wine. Carbon dioxide is used in breadmaking to help the dough rise.

Question 2:
Why do muscles carry out cellular respiration that produces lactic acid during vigorous training?

To provide the energy needed as well as enabling an individual to carry out activities.

Question 3:
Why does cellular respiration in muscles that produce lactic acid supply less energy compared to aerobic respiration?

This is because glucose oxidation is incomplete and a part of the chemical energy is still tied in the lactic acid molecule.

Question 4:
Explain why an individual usually feels tired faster compared with an athlete, when both of them are running together.

An athlete usually has more mitochondria in the muscle cells. Increased uptake of oxygen and oxidation of lactic acid reduces muscle fatigue.

Question 5:
A 100-metre sprinter usually holds his breath while running compared with a long-distance runner. After running, the sprinter needs seven litres of oxygen to remove the lactic acid in his muscle cells. Explain this difference between the sprinter and the long-distance runner.

100 m runners complete the race fast by holding their breath. By doing so, the runner uses existing oxygen efficiently. However, lactic acid is accumulated because the oxygen supply to the muscles is insufficient. On the other hand, long distance runners who run at a slower speed are able to dispose off the lactic acid accumulated in the early stages of running. Long distance runners cannot hold their breath because lactic acid accumulation causes rapid muscle fatigue. As such, long distance runners need to breath throughout the race.

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