Question 1

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

Accepted Answer

They transmit the action potential deep into the muscle fiber, ensuring synchronized contraction.

Question 2

A patient is experiencing muscle weakness due to a defect in the sarcoplasmic reticulum. Which process is most directly affected?

Accepted Answer

Release and reuptake of calcium ions during muscle contraction and relaxation.

Question 3

Which of the following correctly matches the muscle term with its definition?

Accepted Answer

Agonist: The primary muscle responsible for a movement.

Question 4

During the sliding filament mechanism of muscle contraction, which sequence of events is correct?

Accepted Answer

Ca$$^{2+}$$ binds to troponin, tropomyosin shifts, myosin binds to actin, power stroke occurs.

Question 5

Which of the following best explains why cardiac muscle cannot undergo tetanus (sustained contraction)?

Accepted Answer

Cardiac muscle cells have long refractory periods due to prolonged Ca$$^{2+}$$ influx.

Question 6

A neuron receives multiple excitatory and inhibitory inputs at its dendrites. Which process determines whether an action potential will be generated?

Accepted Answer

Integration of postsynaptic potentials at the axon hillock.

Question 7

Which of the following is a characteristic of fast glycolytic (Type IIb) skeletal muscle fibers?

Accepted Answer

Low myoglobin content and rapid fatigue.

Question 8

Which of the following best describes the difference between isotonic and isometric muscle contractions?

Accepted Answer

Isotonic contractions involve muscle shortening or lengthening with constant tension; isometric contractions involve tension without changing muscle length.

Question 9

Which of the following statements about the plasma membrane is correct?

Accepted Answer

It consists of a phospholipid bilayer with embedded proteins and cholesterol.

Question 10

A red blood cell is placed in a hypotonic solution. What will happen to the cell, and why?

Accepted Answer

It will swell and possibly burst because water moves in by osmosis.

Question 11

Which of the following glial cells is responsible for forming the myelin sheath in the central nervous system?

Accepted Answer

Oligodendrocytes

Question 12

Which of the following best describes the role of the neuromuscular junction?

Accepted Answer

It is the site where a motor neuron communicates with a skeletal muscle fiber to initiate contraction.

Question 13

Which of the following is true regarding the propagation of an action potential along a myelinated axon?

Accepted Answer

The action potential jumps from one node of Ranvier to the next, a process called saltatory conduction.

Question 14

Which of the following best describes the function of the Z disc in a sarcomere?

Accepted Answer

It separates one sarcomere from the next and anchors thin filaments.

Question 15

Which of the following is a function of the respiratory muscles?

Accepted Answer

They facilitate the movement of air into and out of the lungs by changing thoracic volume.

Question 16

Which of the following best explains why smooth muscle can maintain contractions for long periods with minimal energy expenditure?

Accepted Answer

Smooth muscle uses a latch-bridge mechanism that allows sustained tension with low ATP consumption.

Question 17

Which of the following neural circuits is best suited for amplifying a signal to activate multiple effectors, such as in a withdrawal reflex?

Accepted Answer

Diverging circuit

Question 18

Which of the following best describes the role of ATP in muscle contraction?

Accepted Answer

ATP hydrolysis energizes the myosin head, allowing it to bind to actin and perform the power stroke.

Question 19

A patient presents with muscle spasms due to excessive acetylcholine in the synaptic cleft. Which of the following best explains this phenomenon?

Accepted Answer

Acetylcholinesterase is inhibited, preventing breakdown of acetylcholine.

Question 20

Which of the following best describes the difference between facilitated diffusion and active transport across the plasma membrane?

Accepted Answer

Facilitated diffusion moves substances down their concentration gradient without energy; active transport moves substances against their gradient using ATP.

Skeletal Muscles, Membrane Transport, and Excitable Cells: Study Guide

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