Question 1

Which of the following processes supplies ATP for the first few seconds of muscle contraction before other sources are utilized?

Accepted Answer

Immediate cytosolic reactions using stored ATP and creatine phosphate

Question 2

During muscle contraction, ATP is required for all of the following EXCEPT:

Accepted Answer

Synthesizing glycogen from glucose

Question 3

Which equation correctly represents the reaction catalyzed by creatine kinase in muscle fibers?

Accepted Answer

$$\mathrm{Creatine~phosphate} + \mathrm{ADP} \rightarrow \mathrm{ATP} + \mathrm{Creatine}$$

Question 4

A sprinter is running a 100-meter dash lasting about 10 seconds. Which energy source is primarily used during this activity?

Accepted Answer

Immediate cytosolic reactions using stored ATP and creatine phosphate

Question 5

After immediate energy sources are depleted, which process supplies ATP for up to 40 seconds of sustained muscle contraction?

Accepted Answer

Glycolysis breaking down glucose to pyruvate

Question 6

Which statement best describes glycolysis in muscle cells?

Accepted Answer

It breaks down glucose into pyruvate in the cytosol and does not require oxygen directly

Question 7

Which of the following is TRUE regarding oxidative catabolism in muscle fibers?

Accepted Answer

It requires oxygen directly and occurs in mitochondria

Question 8

A marathon runner relies on which energy source after several minutes of continuous activity?

Accepted Answer

Oxidative catabolism

Question 9

Which molecule acts as an oxygen carrier within muscle fibers, releasing oxygen as needed during aerobic metabolism?

Accepted Answer

Myoglobin

Question 10

Which of the following best explains why creatine supplementation may have minimal effects on endurance-type activities?

Accepted Answer

Endurance activities rely primarily on oxidative catabolism, which does not use creatine phosphate as a major ATP source

Question 11

Which of the following is a potential risk associated with excessive creatine supplementation?

Accepted Answer

Kidney damage and unnecessary weight gain due to water retention

Question 12

Which of the following equations correctly represents the net ATP yield from glycolysis of one glucose molecule?

Accepted Answer

$$\mathrm{Glucose} \rightarrow 2~\mathrm{Pyruvate} + 2~\mathrm{ATP} + 2~\mathrm{NADH}$$

Question 13

Which of the following is the final electron acceptor in oxidative catabolism within mitochondria?

Accepted Answer

Oxygen ($$O_2)$$

Question 14

A patient with a genetic defect in myoglobin synthesis would most likely experience which symptom during prolonged exercise?

Accepted Answer

Reduced ability to store and release oxygen in muscle fibers, leading to early fatigue

Question 15

Which of the following statements about muscle energy sources is CORRECT?

Accepted Answer

Glucose is the preferred fuel for muscle fibers during oxidative catabolism

Question 16

Which process is most responsible for the rapid production of ATP during the first 10 seconds of maximal muscle contraction?

Accepted Answer

Creatine phosphate donation of phosphate to ADP

Question 17

If a muscle cell is deprived of oxygen, which process will continue to supply ATP for a short period?

Accepted Answer

Glycolytic catabolism

Question 18

Which of the following best explains why muscle fibers can use fatty acids and amino acids as fuel during oxidative catabolism?

Accepted Answer

Fatty acids and amino acids are broken down in mitochondria to produce ATP when glucose is unavailable

Question 19

Which of the following is a real-world consequence of ATP depletion in muscle fibers during intense exercise?

Accepted Answer

Muscle fatigue occurs due to inability to maintain ion gradients and crossbridge cycling

Energy Sources for Skeletal Muscle Contraction

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