BiologyNEB 2082 (MCQs)
If a plant is placed in a sealed bell jar with limited oxygen, how will its energy production be affected over time? a) ATP production will increase due to higher glycolysis. b) The plant will rely…
1If a plant is placed in a sealed bell jar with limited oxygen, how will its energy production be affected over time? a) ATP production will increase due to higher glycolysis. b) The plant will rely on anaerobic respiration producing less ATP. c) The citric acid cycle will become faster to make up for lack of oxygen. d) The electron transport chain will continue functioning normally. GROUP: A | Section : II (Zoology) | 6 × 1 = 6
Answer
Answer
b) The plant will rely on anaerobic respiration producing less ATP.
In the presence of limited oxygen, aerobic respiration (which yields approximately 36–38 ATP per glucose molecule) is inhibited because oxygen is the final electron acceptor in the electron transport chain (ETC). Without sufficient oxygen, the ETC stops, and the citric acid cycle also halts due to the accumulation of NADH and FADH₂. Consequently, the plant cells switch to anaerobic respiration (fermentation), which involves only glycolysis. Glycolysis produces a net gain of only 2 ATP per glucose molecule, significantly less than aerobic respiration. Therefore, overall ATP production decreases over time.
- Option (a) is incorrect because while glycolysis may initially increase, the total ATP yield is much lower than in aerobic conditions.
- Option (c) is incorrect because the citric acid cycle requires NAD⁺ and FAD, which are regenerated by the ETC; without oxygen, these carriers remain reduced, stopping the cycle.
- Option (d) is incorrect because the ETC depends on oxygen as the terminal electron acceptor; without it, the chain backs up and ceases function.
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