Fast muscle fibers contain a high proportion of myofibrils, which allows the fibers to generate high amounts of force. However, this leaves little room in the fibers for other cellular components, including mitochondria. The opposite is true for slow muscle fibers. Does this information support or refute what you know about the fatigue-susceptibility of fast and slow fibers? Why or why not?
A) It supports it because if fast fibers have less room for mitochondria than slow fibers do, they cannot produce as much ATP and thus are less fatigue-resistant than slow fibers.
B) It supports it because if fast fibers have less room for mitochondria than slow fibers do, they can produce more ATP than slow fibers and thus are more fatigue-resistant than slow fibers.
C) It refutes it because if fast fibers have less room for mitochondria than slow fibers do, they can produce more ATP than slow fibers and thus are less fatigue-resistant than slow fibers.
D) It refutes it because if fast fibers have less room for mitochondria than slow fibers do, they cannot produce as much ATP and thus are more fatigue-resistant than slow fibers.

Question

Quizplus · Accepted Answer

The information presented supports the idea that fast fibers are more susceptible to fatigue than slow fibers because they have less room for mitochondria, which are responsible for producing ATP, the energy source required for muscle contractions. Without sufficient ATP production, fast fibers will tire out quicker and be less fatigue-resistant than slow fibers.

Fast Muscle Fibers Contain a High Proportion of Myofibrils, Which