A rabbit fleeing a coyote and a duck\'s extended flight during migration both in

Question

A rabbit fleeing a coyote and a duck's extended flight during migration both involve muscular activity with high demands for metabolic fuel. However, the source of fuel and the pathways for ATP production differ. A rabbit's short-term need for ATP is supplied by the breakdown of stored glycogen and glycolysis under anaerobic conditions. ATP for a duck's extended flight is supplied by the breakdown of fats to acetyl-CoA, the citric acid cycle, and oxidative phosphorylation. The short-term intense run and the long-term flight require coordinated regulatory controls on the central metabolic pathways of glycolysis, citric acid cycle, and oxidative phosphorylation. Match the actions of metabolic regulators with the type of muscular activity. Short-term, intense muscular activity Long-term, continuous muscular activity

Explanation / Answer

Answer:

Short-term, intense muscular activity:

i. Low [O2] inhibits the citric acid cycle

ii. High [AMP] stimulates PFK-1 activity

iii. Low [acetyl-CoA] relieves pyruvate kinase inhibition

Long-term, continuous muscular activity:

i. High [ATP] inhibits PFK-1

ii. Citrate inhibits PFK-1

Explanation:

Under resting conditions, [ATP] is high and [AMP] low because the total adenine nucleotide pool is constant. [Citrate] and [acetyl-CoA] are intermediate because O2 is not limiting and the citric acid cycle is functioning.

Under conditions of active exertion, O2 becomes limiting and ATP synthesis decreases. Consequently, [ATP] is relatively low and [AMP] relatively high, compared with aerobic conditions. [Citrate] and [acetyl-CoA] are low. These changes release the inhibition of glycolysis and stimulate lactic acid production.

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