Mark the following statements as true or false. If a statement is false, correct it to make a true statement.


d. A muscle fiber changes length during isotonic concentric and isotonic eccentric contractions.

Which of the following statements accurately describes the role of ATP in a muscle contraction?

a. ATP is directly responsible for the power stroke.

b. ATP moves troponin and tropomyosin away from actin.

c. ATP breaks the actin/myosin attachment and 'cocks' the myosin head.

d. ATP causes the myofilaments to shorten.

A muscle fiber relaxes when:

a. the concentration of Ca2+ in the cytosol returns to resting levels.

b. the supply of ATP is exhausted.

c. Ca2+ flood the cytosol.

d. acetylcholine is released from the axon terminal and the sarcolemma depolarizes.

Which of the following energy sources would provide the majority of the ATP for a person running a 26-mile marathon?

a. Stored ATP

b. Glycolytic catabolism

c. Oxidative catabolism

d. Creatine phosphate

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

b. Stimulation by a motor neuron before a muscle fiber has fully relaxed results in a condition called wave summation.