Q: Which equation best represents the action of the Na+/K+ pump in maintaining resting membrane potential in skeletal muscle cells?

$$3\text{Na}^+ \text{out} : 2\text{K}^+ \text{in}$$

Q: Which equation best represents the net ATP yield from aerobic cellular respiration of one glucose molecule?

$$\text{Glucose} + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + 36\text{ATP}$$

Question 1

Which of the following best describes the structural difference between skeletal, cardiac, and smooth muscle tissue?

Accepted Answer

Skeletal muscle fibers are cylindrical, multinucleate, and striated; cardiac muscle fibers are branched, striated, and have intercalated discs; smooth muscle fibers are spindle-shaped, uninucleate, and lack striations.

Question 2

During muscle contraction, which event directly triggers the exposure of the myosin binding site on actin?

Accepted Answer

Calcium ions bind to troponin, causing tropomyosin to move away from the binding site.

Question 3

Which equation best represents the action of the Na+/K+ pump in maintaining resting membrane potential in skeletal muscle cells?

Accepted Answer

$$3	ext{Na}^+ 	ext{out} : 2	ext{K}^+ 	ext{in}$$

Question 4

A patient presents with muscle weakness due to an autoimmune disease that destroys acetylcholine receptors at the neuromuscular junction. Which condition is most likely?

Accepted Answer

Myasthenia gravis

Question 5

Which of the following best explains why the A-band remains the same length during muscle contraction?

Accepted Answer

The A-band contains the region of overlap between thick and thin filaments, and the thick filaments do not change length.

Question 6

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

Accepted Answer

ACh is released, binds to receptors, Na+ channels open, action potential generated, Ca2+ released from SR, contraction begins.

Question 7

Which muscle fiber type is most resistant to fatigue and why?

Accepted Answer

Slow fibers, because they have a robust capillary network and contain myoglobin.

Question 8

A muscle is stimulated at a frequency that does not allow complete relaxation between twitches, resulting in near-peak tension. What is this phenomenon called?

Accepted Answer

Incomplete tetanus

Question 9

Which of the following best describes the role of creatine phosphate in muscle contraction?

Accepted Answer

It converts ADP to ATP, providing a rapid source of energy.

Question 10

During peak muscle activity, which metabolic pathway is primarily responsible for ATP production, and what is a major byproduct?

Accepted Answer

Glycolysis; lactic acid

Question 11

Which equation best represents the net ATP yield from aerobic cellular respiration of one glucose molecule?

Accepted Answer

$$	ext{Glucose} + 6	ext{O}_2 ightarrow 6	ext{CO}_2 + 6	ext{H}_2	ext{O} + 36	ext{ATP}$$

Question 12

Which of the following best explains muscle hypertrophy?

Accepted Answer

Increase in muscle size due to repeated exhaustive stimulation, resulting in more mitochondria, glycogen, myofibrils, and myofilaments.

Question 13

Which of the following is true regarding muscle tone?

Accepted Answer

Muscle tone is the resting tension in skeletal muscle, maintained by some motor units always being active.

Question 14

Which statement best describes the Cori cycle during muscle activity?

Accepted Answer

Lactate produced in muscles is converted to glucose in the liver, which is then returned to muscles.

Question 15

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

Accepted Answer

Titin connects thick filaments to Z-lines and helps recoil the sarcomere after contraction.

Question 16

A muscle contraction in which the muscle length does not change, but tension increases, is called:

Accepted Answer

Isometric contraction

Question 17

Which of the following is a real-life example of a second-class lever in the human body?

Accepted Answer

Plantar flexion (standing on tiptoe)

Question 18

Which protein is responsible for holding F-actin strands together in the thin filament?

Accepted Answer

Nebulin

Question 19

Which clinical condition is characterized by sustained, powerful muscle contractions due to a bacterial toxin that inhibits motor neuron inhibition?

Accepted Answer

Tetanus

Skeletal Muscle Tissue and the Muscular System: Structure, Function, and Physiology

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