Question

a weightlifter is using heavy weights in short bursts for a competition. because his muscle cells need to do this, which of the following processes is most likely going on in the muscles of the weightlifter as he competes in the event?
a as the cells run out of oxygen, they die off gradually and the weightlifter’s muscles have fewer contracting fibers.
b as the cells runs out of oxygen, they will continue to make the same amount of atp, since oxygen is not required to make atp.
c the cells will never run out of oxygen if the weightlifter is breathing.
d as the cells run out of oxygen they switch to anaerobic respiration, which allows the cells to make small amounts of atp in the absence of oxygen.

Explanation:

During short - burst, heavy - weight lifting (anaerobic exercise), muscle cells quickly use up available oxygen. Then, they switch to anaerobic respiration (like lactic acid fermentation) to produce ATP. Option A is wrong because cells don't just die off gradually. Option B is wrong as anaerobic respiration produces less ATP than aerobic respiration. Option C is wrong because in short bursts, oxygen in muscle cells can be depleted even if the weightlifter is breathing. Option D correctly describes the switch to anaerobic respiration for ATP production in oxygen - limited, short - burst exercise.

Answer:

D. As the cells run out of oxygen they switch to anaerobic respiration, which allows the cells to make small amounts of ATP to the muscles