Q: Which equation best represents the relationship between ATP hydrolysis and muscle contraction?

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

Question 1

Which of the following best describes the process by which muscle tissue transforms chemical energy into mechanical energy?

Accepted Answer

Muscle tissue uses ATP to generate cycling cross bridges and tension, converting chemical potential energy into mechanical energy.

Question 2

Which type of muscle tissue is striated, voluntary, and responsible for movement of bones?

Accepted Answer

Skeletal muscle

Question 3

A patient suffers from a genetic disorder that affects the protein dystrophin. Which of the following is most likely to occur?

Accepted Answer

The structural integrity of the sarcolemma is compromised, leading to muscle weakness.

Question 4

Which of the following is NOT a characteristic shared by all muscle tissue types?

Accepted Answer

Striation

Question 5

During the sliding filament model of contraction, what happens to the H zone and A band?

Accepted Answer

The H zone disappears and the A bands move closer together.

Question 6

Which equation best represents the relationship between ATP hydrolysis and muscle contraction?

Accepted Answer

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

Question 7

Which structure in skeletal muscle fiber stores calcium ions and releases them during muscle contraction?

Accepted Answer

Sarcoplasmic reticulum

Question 8

A muscle fiber is stimulated by a motor neuron. Which neurotransmitter is released at the neuromuscular junction to initiate contraction?

Accepted Answer

Acetylcholine (ACh)

Question 9

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

Accepted Answer

ATP is no longer produced, so myosin heads remain bound to actin, causing muscles to stay contracted.

Question 10

Which of the following is the correct sequence of events for excitation-contraction (E-C) coupling in skeletal muscle?

Accepted Answer

Action potential propagates along sarcolemma, travels down T tubules, triggers Ca$$^{2+}$$ release from SR, Ca$$^{2+}$$ binds to troponin, cross bridges form.

Question 11

Which of the following best describes the role of T tubules in muscle contraction?

Accepted Answer

They transmit action potentials deep into the muscle fiber, triggering Ca$$^{2+}$$ release from the sarcoplasmic reticulum.

Question 12

Which of the following is a function of the elastic filament titin in the myofibril?

Accepted Answer

It helps the muscle fiber recoil after stretch and resists excessive stretching.

Question 13

A muscle fiber is unable to contract even though it receives a normal action potential. Which of the following is the most likely cause?

Accepted Answer

Insufficient Ca$$^{2+}$$ release from the sarcoplasmic reticulum prevents cross bridge formation.

Question 14

Which of the following best describes the arrangement of thick and thin filaments in a sarcomere?

Accepted Answer

Thick filaments are surrounded by a hexagonal arrangement of six thin filaments.

Question 15

Which of the following is true regarding the role of calcium ions in muscle contraction?

Accepted Answer

Calcium binds to troponin, causing tropomyosin to move and expose binding sites on actin for myosin.

Question 16

Which of the following best explains why skeletal muscle fibers are multinucleated?

Accepted Answer

They are formed by the fusion of multiple myoblasts during development.

Question 17

Which of the following is the correct order of events at the neuromuscular junction leading to muscle contraction?

Accepted Answer

AP arrives at axon terminal, Ca$$^{2+}$$ channels open, ACh released, ACh binds to receptors, Na$$^+$$ enters muscle fiber, AP generated in sarcolemma.

Question 18

Which of the following best describes the function of the perimysium in skeletal muscle?

Accepted Answer

It surrounds fascicles, which are groups of muscle fibers.

Question 19

Which of the following is a direct muscle attachment to bone?

Accepted Answer

Epimysium fused to periosteum of bone or perichondrium of cartilage.

Question 20

Which of the following is true regarding the refractory period during an action potential in muscle fibers?

Accepted Answer

A muscle fiber cannot be stimulated again until repolarization is complete.

Chapter 9 A- Muscle Tissue: Structure, Function, and Contraction Mechanisms

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