Question 1

Which of the following statements best describes the role of the sarcoplasmic reticulum (SR) in skeletal muscle contraction?

Accepted Answer

The SR stores and releases calcium ions, which are essential for initiating muscle contraction.

Question 2

During a muscle twitch, which phase corresponds to the time when calcium ions are actively pumped back into the sarcoplasmic reticulum?

Accepted Answer

The relaxation period

Question 3

A patient is experiencing muscle fatigue after prolonged exercise. Which of the following is LEAST likely to contribute to this fatigue?

Accepted Answer

Increased synthesis of myoglobin

Question 4

Which equation correctly represents the net ATP yield from glycolysis of one glucose molecule under anaerobic conditions?

Accepted Answer

$$2 	ext{ ATP}$$

Question 5

Which protein is found in thin filaments and directly binds to calcium ions to initiate contraction?

Accepted Answer

Troponin

Question 6

A muscle fiber is stimulated repeatedly at a high frequency, resulting in sustained contraction without relaxation. What is this phenomenon called?

Accepted Answer

Tetanus

Question 7

Which of the following best explains why slow-twitch muscle fibers are more resistant to fatigue than fast-twitch fibers?

Accepted Answer

Slow-twitch fibers have more mitochondria and rely on oxidative metabolism for ATP production.

Question 8

Which of the following is NOT a property of muscle cells?

Accepted Answer

Osmosis

Question 9

A motor unit consists of:

Accepted Answer

A single motor neuron and all the muscle fibers it innervates

Question 10

Which of the following best describes the function of acetylcholine (ACh) at the neuromuscular junction?

Accepted Answer

ACh binds to receptors on the muscle cell membrane, causing sodium channels to open and initiate an action potential.

Question 11

Which of the following muscle types is involuntary and found only in the heart?

Accepted Answer

Cardiac muscle

Question 12

Which of the following correctly matches the band or line in a sarcomere with its description?

Accepted Answer

A band: region where both thick and thin filaments overlap

Question 13

If oxygen is not available during muscle contraction, pyruvate is converted to which molecule?

Accepted Answer

Lactic acid

Question 14

Which of the following is the correct sequence of events in skeletal muscle contraction after an action potential reaches the axon terminal?

Accepted Answer

ACh release → ACh binds to receptors → Na$$^+$$ influx → action potential in muscle fiber

Question 15

Which of the following statements about myofibrils is TRUE?

Accepted Answer

Myofibrils are cylindrical organelles composed of bundles of specialized proteins for contraction.

Question 16

A muscle fiber is unable to respond to a second stimulus during which phase?

Accepted Answer

Refractory period

Question 17

Which of the following is a function of muscle tissue?

Accepted Answer

Stabilizing joints

Question 18

Which of the following best describes the process of recruitment in muscle contraction?

Accepted Answer

Increasing the number of motor units stimulated to produce greater force

Question 19

Which of the following is the main source of energy for muscle contraction during the first few seconds of intense activity?

Accepted Answer

ATP stored in the muscle fiber

Question 20

Which of the following statements about fast-twitch muscle fibers is CORRECT?

Accepted Answer

Fast-twitch fibers have fewer mitochondria and rely mainly on glycolytic catabolism for ATP production.

Muscle Tissue: Structure, Function, and Physiology

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