Which statement about slow-twitch and fast-twitch muscles is true?
A) The first is smooth muscle and the second is skeletal muscle.
B) They express different genes coding for their myosin molecules.
C) Fast-twitch muscles occur only in mammals.
D) They typically have similar numbers of mitochondria per cell.
E) They both compensate for low ATPase activity by recycling their actin-myosin bridges.

Question

Quizplus · Accepted Answer

Slow-twitch and fast-twitch muscles express different genes coding for their myosin molecules. Slow-twitch muscles contain more myosin with a slow ATPase activity, while fast-twitch muscles contain more myosin with a fast ATPase activity. This difference in myosin expression and activity contributes to the different functional properties of these two muscle types. The other choices are incorrect.

Which Statement About Slow-Twitch and Fast-Twitch Muscles Is True