Migrating birds often cross the Gulf of Mexico in a single flight, and their flight muscles demand extreme endurance. An examination of the muscles used to perform this activity would show that they
A) have substantial reserves of fuel.
B) have low levels of ATPase activity.
C) are well-supplied with blood vessels.
D) have many mitochondria.
E) All of the above

Question

Quizplus · Accepted Answer

Migrating birds need to fly extended distances without stopping. This activity requires their flight muscles to have substantial reserves of fuel - this rules out option B. Additionally, these muscles should have low levels of ATPase activity because if they burned through their fuel too fast, they could not generate sufficient energy for the duration of their journey. Furthermore, their muscles should be well-supplied with blood vessels to provide oxygen and nutrients for energy production to the muscle fibers. Finally, the muscles used by migrating birds for flight contain many mitochondria - organelles that generate ATP by oxidative phosphorylation via the electron transport chain, which drive the birds' flight muscles.

Migrating Birds Often Cross the Gulf of Mexico in a Single