Question 1

Which muscle fiber type is most resistant to fatigue and primarily uses fatty acids as its main fuel source?

Accepted Answer

Type I (Slow-twitch, oxidative)

Question 2

During the initial 10 seconds of intense muscle activity, which ATP regeneration pathway is most active?

Accepted Answer

Creatine phosphate system (phosphocreatine)

Question 3

What is the correct sequence of events in excitation-contraction coupling in skeletal muscle?

Accepted Answer

Acetylcholine release → Depolarization of sarcolemma → Action potential travels down T-tubules → Ca$$^{2+}$$ release from sarcoplasmic reticulum

Question 4

Which enzyme catalyzes the reaction $$	ext{Phosphocreatine} + 	ext{ADP} ightleftharpoons 	ext{Creatine} + 	ext{ATP} in $$muscle cells?

Accepted Answer

Creatine kinase

Question 5

A sprinter completes a 100-meter dash in under 10 seconds. Which metabolic pathway is primarily responsible for ATP regeneration during this activity?

Accepted Answer

Creatine phosphate system

Question 6

Which of the following best describes the role of Ca$$^{2+} in $$muscle contraction?

Accepted Answer

Ca$$^{2+}$$ binds to troponin C, exposing actin binding sites

Question 7

Which regulatory molecule inhibits glycolysis in resting muscle by acting on phosphofructokinase-1 (PFK-1)?

Accepted Answer

Citrate

Question 8

During prolonged aerobic exercise, which hormone is primarily responsible for activating hormone-sensitive lipase in adipose tissue, leading to increased blood fatty acids?

Accepted Answer

Epinephrine

Question 9

Which of the following is a direct effect of AMP-activated protein kinase (AMPK) activation in exercising muscle?

Accepted Answer

Activation of glycolysis and glycogenolysis

Question 10

In the context of muscle contraction, what is the role of ATP during the detachment phase?

Accepted Answer

ATP binding to myosin causes release from actin

Question 11

Which metabolic adaptation is most likely to occur in skeletal muscle after endurance training?

Accepted Answer

Increase in oxidative enzyme activity and capillary density

Question 12

During high-intensity exercise lasting longer than 10 seconds, which pathway is responsible for the production of ATP and lactate?

Accepted Answer

Anaerobic glycolysis from muscle glycogen

Question 13

Which of the following best explains the fate of lactate produced during anaerobic glycolysis in muscle?

Accepted Answer

It is exported to the liver for gluconeogenesis via the Cori cycle

Question 14

Which of the following is a consequence of increased citrate levels in resting muscle?

Accepted Answer

Inhibition of PFK-1 and activation of ACC, leading to decreased fatty acid oxidation

Question 15

Which signaling pathway is activated by epinephrine to stimulate glycogenolysis in skeletal muscle?

Accepted Answer

Epinephrine → Gs protein → adenylate cyclase → cAMP → PKA → phosphorylase kinase

Question 16

Which of the following changes is NOT a typical metabolic effect of endurance training in skeletal muscle?

Accepted Answer

Decrease in lactate clearance

Question 17

During prolonged exercise, which substrate becomes the dominant fuel for muscle after glycogen stores are depleted?

Accepted Answer

Fatty acids

Question 18

Which of the following best describes the effect of AMPK activation on fatty acid metabolism in muscle?

Accepted Answer

AMPK activation decreases malonyl-CoA, relieving inhibition of CPT I and increasing fatty acid oxidation

Question 19

Which of the following is a direct effect of training on muscle fiber composition?

Accepted Answer

Shift toward more oxidative Type IIa fibers

Question 20

A patient with a deficiency in creatine kinase would most likely experience which symptom during short, intense exercise?

Accepted Answer

Rapid fatigue due to inability to regenerate ATP quickly

Biochemistry of Skeletal Muscle: Integrated Musculoskeletal System

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