Question

figure 1. atp production by three metabolic pathways following the start of an intense period of exercise
which of the following correctly uses the data to justify the claim that the phosphagen system is an immediate, short - term source of atp for muscle cells?
a atp production by the phosphagen system increases and decreases rapidly following the start of the exercise period.
b atp production by the phosphagen system increases gradually and continuously throughout the entire exercise period.
c the atp produced by the phosphagen system contains more energy per molecule than does the atp produced by the other pathways.
d atp hydrolysis in muscle cells occurs immediately after the start of the exercise period but stops before the end of the exercise period.

Explanation:

The claim is about the phospagen system being an immediate, short - term source. Option A shows rapid increase and decrease in ATP production by the phospagen system after exercise starts, which is consistent with it being an immediate, short - term source. Option B describes a gradual and continuous increase which is not short - term. Option C is about energy per molecule, not about short - term production. Option D is about ATP hydrolysis, not production by the phospagen system.

Answer:

A. ATP production by the phospagen system increases and decreases rapidly following the start of the exercise period.