Final answer:
During peak levels of muscle exertion, the mitochondria can supply about 80 percent of the energy required by the muscle.
Step-by-step explanation:
During peak levels of muscle exertion, the mitochondria can supply about 80 percent of the energy required by the muscle. When the muscle is working at its maximum capacity, the mitochondria play a crucial role in generating ATP (adenosine triphosphate), which is the energy currency of cells. ATP is produced through aerobic respiration, which takes place in the mitochondria, and this process can supply the majority of the energy needed by the muscle during peak exertion.