Q: Which of the following equations correctly 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 difference between the contraction mechanisms of skeletal and smooth muscle cells?

Accepted Answer

Skeletal muscle contraction is initiated by calcium binding to troponin, whereas smooth muscle contraction is initiated by calcium binding to calmodulin.

Question 2

A patient is injected with curare, a toxin that blocks acetylcholine receptors at the neuromuscular junction. What is the most immediate effect on skeletal muscle contraction?

Accepted Answer

Muscle fibers will not contract because the action potential cannot be transmitted across the neuromuscular junction.

Question 3

Which structural protein is mutated in Duchenne muscular dystrophy, leading to muscle fiber fragility?

Accepted Answer

Dystrophin

Question 4

During the contraction cycle, which step directly requires the hydrolysis of ATP?

Accepted Answer

Re-cocking of the myosin head

Question 5

A muscle fiber is stimulated at a frequency that does not allow complete relaxation between stimuli, resulting in increased tension. What is this phenomenon called?

Accepted Answer

Wave summation

Question 6

Which of the following best explains why rigor mortis occurs after death?

Accepted Answer

ATP is no longer produced, so myosin heads cannot detach from actin.

Question 7

Which of the following is the correct order of connective tissue layers from superficial to deep in a skeletal muscle?

Accepted Answer

Epimysium, perimysium, endomysium

Question 8

A marathon runner is likely to have a higher proportion of which muscle fiber type in their leg muscles?

Accepted Answer

Slow oxidative fibers

Question 9

Which of the following best describes the role of the sarcoplasmic reticulum in muscle contraction?

Accepted Answer

It stores and releases calcium ions necessary for contraction.

Question 10

Which of the following equations correctly 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 11

Which of the following best explains why a muscle can generate its greatest tension at an optimal length?

Accepted Answer

There is maximal overlap between thick and thin filaments, allowing the most cross-bridges to form.

Question 12

Which of the following is a key difference between single-unit and multiunit smooth muscle?

Accepted Answer

Single-unit smooth muscle fibers are connected by gap junctions, allowing coordinated contraction, while multiunit smooth muscle fibers are not.

Question 13

Which of the following best describes the function of myoglobin in skeletal muscle fibers?

Accepted Answer

It binds oxygen for use during aerobic respiration.

Question 14

A muscle is producing force but not changing length. What type of contraction is this?

Accepted Answer

Isometric contraction

Question 15

Which of the following is NOT a source of ATP for muscle contraction?

Accepted Answer

Glycogenolysis without ATP production

Question 16

Which of the following best describes the role of satellite cells in skeletal muscle?

Accepted Answer

They fuse with muscle fibers to aid in growth and repair.

Question 17

Which of the following is a characteristic of fast glycolytic muscle fibers?

Accepted Answer

Large diameter and rapid, powerful contractions

Question 18

Which of the following events must occur at the neuromuscular junction for a muscle to relax?

Accepted Answer

Acetylcholine is broken down by acetylcholinesterase.

Question 19

Which of the following best explains why a small motor unit allows for fine motor control?

Accepted Answer

It contains fewer muscle fibers per neuron, allowing for precise movements.

Question 20

Which of the following best describes the function of titin in the sarcomere?

Accepted Answer

It anchors thick filaments to the Z disc and provides elasticity.

Anatomy & Physiology Exam 3 Review: Muscle Tissue Study Guidance

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