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

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

Question 1

Which of the following best describes the main function of skeletal muscle tissue?

Accepted Answer

Moves or stabilizes the position of the skeleton; guards entrances and exits to the digestive, respiratory, and urinary tracts; generates heat; protects internal organs.

Question 2

Which structure is responsible for transmitting the action potential deep into the muscle fiber, triggering calcium release from the sarcoplasmic reticulum?

Accepted Answer

T tubule

Question 3

During muscle contraction, which of the following changes occur in the sarcomere?

Accepted Answer

The H zone and I band shorten, while the A band remains the same length.

Question 4

Which protein blocks the active site on actin in a resting muscle, preventing myosin binding?

Accepted Answer

Tropomyosin

Question 5

What is the role of ATP in muscle contraction and relaxation?

Accepted Answer

ATP is required to detach the myosin head from actin and to reset the myosin head for another cycle.

Question 6

A patient with Duchenne Muscular Dystrophy (DMD) lacks which protein, leading to progressive muscle weakness?

Accepted Answer

Dystrophin

Question 7

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

Accepted Answer

Muscle → Fascicle → Muscle fiber → Myofibril → Sarcomere

Question 8

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

Accepted Answer

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

Question 9

Which of the following is true regarding the neuromuscular junction?

Accepted Answer

Acetylcholine (ACh) is released from the motor neuron and binds to receptors on the sarcolemma, causing sodium ions to enter the muscle fiber.

Question 10

Which of the following best explains why males are more commonly affected by Duchenne Muscular Dystrophy (DMD)?

Accepted Answer

DMD is an X-linked recessive disorder, so males (with only one X chromosome) are more likely to express the disease.

Question 11

During the contraction cycle, what triggers the exposure of the active site on actin?

Accepted Answer

Release of calcium ions from the sarcoplasmic reticulum, which bind to troponin

Question 12

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

Accepted Answer

Circulating blood throughout the body

Question 13

Which band in the sarcomere remains unchanged during muscle contraction?

Accepted Answer

A band

Question 14

What is the primary effect of the absence of dystrophin in Duchenne Muscular Dystrophy?

Accepted Answer

Muscle fibers are not properly anchored to the extracellular matrix, leading to damage during contraction.

Question 15

Which of the following steps occurs LAST in the muscle contraction cycle?

Accepted Answer

Myosin reactivation (ATP hydrolysis resets myosin head)

Question 16

Which of the following best describes the relationship between sarcomere length and muscle tension?

Accepted Answer

Maximum tension is generated when there is optimal overlap between thick and thin filaments.

Question 17

Which of the following is a plausible consequence of repeated muscle contractions without sufficient relaxation?

Accepted Answer

Muscle will enter a state of tetanus, where tension remains high and contractions fuse.

Question 18

Which of the following is the correct sequence of events for muscle contraction at the molecular level?

Accepted Answer

Calcium binds to troponin → Tropomyosin moves → Myosin binds to actin → Power stroke → ATP binds to myosin → Myosin detaches

Question 19

Which of the following best explains why ATP is required for muscle relaxation?

Accepted Answer

ATP is required to detach myosin from actin, allowing the muscle fiber to return to its resting state.

Skeletal Muscle Tissue: Structure, Function, and Contraction Mechanisms

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