Question 1

Which of the following best describes the immediate source of energy for skeletal muscle contraction after stored ATP is depleted?

Accepted Answer

The creatine phosphate reaction catalyzed by creatine kinase

Question 2

A sprinter uses maximal effort for a 10-second dash. Which energy system is primarily supplying ATP during this time?

Accepted Answer

Creatine phosphate reaction

Question 3

Which equation correctly represents the reaction catalyzed by creatine kinase during muscle contraction?

Accepted Answer

$$\mathrm{ADP} + \mathrm{Creatine~phosphate} \xrightarrow{CK} \mathrm{ATP} + \mathrm{Creatine}$$

Question 4

Why does creatine supplementation have minimal effect on endurance-type activities?

Accepted Answer

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

Question 5

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

Accepted Answer

Kidney damage

Question 6

During intense exercise, when oxygen is limited, what is the fate of pyruvate produced by glycolysis in skeletal muscle?

Accepted Answer

It is converted into lactic acid

Question 7

Which of the following statements about glycolytic (anaerobic) catabolism is correct?

Accepted Answer

It splits one glucose molecule into two pyruvate molecules and yields two net ATP

Question 8

After several minutes of sustained muscle activity, which energy system is the dominant source of ATP?

Accepted Answer

Oxidative (aerobic) catabolism

Question 9

Which protein in muscle fibers stores oxygen for use during oxidative catabolism?

Accepted Answer

Myoglobin

Question 10

A patient is experiencing muscle fatigue after a long run. Which fuel source is most likely being used for ATP production at this stage?

Accepted Answer

Fatty acids and amino acids via oxidative catabolism

Question 11

Which of the following best explains why muscle fibers only store a few seconds’ worth of ATP?

Accepted Answer

ATP is unstable and cannot be stored in large amounts

Question 12

Which of the following is a correct sequence of energy source utilization during a 2-minute high-intensity exercise?

Accepted Answer

Creatine phosphate → glycolytic catabolism → oxidative catabolism

Question 13

Which of the following statements about creatine as a dietary supplement is TRUE?

Accepted Answer

Quality control is left to the manufacturer, and the active ingredient may not always be present

Question 14

If a muscle fiber is stimulated 100 times per second, which of the following is most likely to occur?

Accepted Answer

Fused (complete) tetanus

Question 15

Which of the following best describes the effect of the botulinum toxin on skeletal muscle?

Accepted Answer

It blocks acetylcholine release, preventing muscle contraction

Question 16

A muscle fiber is overly stretched before contraction. What is the expected effect on tension production?

Accepted Answer

Tension production decreases because myosin heads cannot effectively bind actin

Question 17

Which type of skeletal muscle fiber is best adapted for prolonged, low-intensity activities such as maintaining posture?

Accepted Answer

Type I (slow oxidative) fibers

Question 18

Which of the following is a characteristic of Type II (fast-twitch) muscle fibers?

Accepted Answer

Rapid contraction and reliance on glycolytic energy sources

Question 19

A patient receives a vaccination against Clostridium tetani. What is the primary purpose of this vaccine?

Accepted Answer

To prevent excessive stimulation and tetanic spasms of skeletal muscles

Question 20

Which of the following best explains why tension is highest during fused (complete) tetanus compared to a single twitch?

Accepted Answer

Calcium ion concentration in the cytosol remains high, allowing more crossbridges to form

Energy Sources for Skeletal Muscle Contraction - 10.5-10.6

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