$$\text{ATP} + \text{H}_2\text{O} \rightarrow \text{ADP} + \text{P}_i + \text{energy}$$

$$\text{Ca}^{2+}$$ binds to troponin, causing tropomyosin to shift and expose myosin-binding sites

Question 1

Which of the following best describes the structural organization of skeletal muscle from largest to smallest unit?

Accepted Answer

Muscle, fascicle, muscle fiber, myofibril, sarcomere

Question 2

During muscle contraction, which band of the sarcomere shortens, and which remains unchanged?

Accepted Answer

I band shortens, A band remains unchanged

Question 3

According to the sliding filament theory, what is the primary role of ATP in muscle contraction?

Accepted Answer

ATP binds to myosin, causing the myosin head to release from actin

Question 4

Which equation best represents the hydrolysis of ATP during muscle contraction?

Accepted Answer

$$	ext{ATP} + 	ext{H}_2	ext{O} ightarrow 	ext{ADP} + 	ext{P}_i + 	ext{energy}$$

Question 5

What is the function of troponin in skeletal muscle contraction?

Accepted Answer

Troponin binds calcium ions, causing tropomyosin to move and expose myosin-binding sites on actin

Question 6

Which of the following best explains why muscle cramps occur?

Accepted Answer

Insufficient ATP prevents myosin from releasing actin, resulting in sustained contraction

Question 7

A patient is experiencing muscle weakness due to a defect in acetylcholine release at the neuromuscular junction. Which process is directly affected?

Accepted Answer

Transmission of the action potential to the muscle fiber

Question 8

Which muscle type is responsible for involuntary movements such as peristalsis in the digestive tract?

Accepted Answer

Smooth muscle

Question 9

During muscle contraction, which of the following events occurs first?

Accepted Answer

Calcium ions bind to troponin

Question 10

Which of the following is a correct sequence of events in the actin-myosin interaction cycle?

Accepted Answer

Myosin head binds to actin, ATP binds to myosin, myosin releases actin, ATP hydrolyzed, myosin reattaches

Question 11

Which of the following best describes the role of calcium ions ($$	ext{Ca}^{2+}) in $$muscle contraction?

Accepted Answer

$$	ext{Ca}^{2+}$$ binds to troponin, causing tropomyosin to shift and expose myosin-binding sites

Question 12

Which of the following is NOT a function of skeletal muscle?

Accepted Answer

Pumping blood

Question 13

A muscle twitch is best described as:

Accepted Answer

A single, brief contraction and relaxation cycle in a muscle fiber

Question 14

Which of the following statements about cardiac muscle is correct?

Accepted Answer

Cardiac muscle cells are striated and connected by intercalated discs

Question 15

Which process is directly responsible for muscle growth after exercise?

Accepted Answer

Hypertrophy, or increase in the size of existing muscle fibers

Question 16

Which of the following best explains the effect of a toxin that blocks acetylcholine receptors at the neuromuscular junction?

Accepted Answer

Muscle contraction is inhibited

Question 17

Which equation represents the relationship between force ($$F$$), mass ($$m$$), and acceleration ($$a) in $$muscle contraction?

Accepted Answer

$$F = m 	imes a$$

Question 18

Which of the following is a characteristic unique to smooth muscle compared to skeletal muscle?

Accepted Answer

Smooth muscle contracts involuntarily

Question 19

A marathon runner experiences muscle fatigue after prolonged activity. Which of the following best explains this phenomenon?

Accepted Answer

Accumulation of lactic acid due to anaerobic metabolism

Muscle Structure and Function: Mechanisms of Animal Movement

Study Guide - Practice Questions