Refer to the graph below, showing the capacity of three systems that provide ATP for muscle contraction. Which of the following statements is true?
A) The system of curve A metabolizes carbohydrates to pyruvate and lactate.
B) The system of curve B comes on line within seconds but lacks sustained efficiency.
C) The system of curve B uses ATP produced by oxidative metabolism.
D) The system of curve C uses preformed ATP and creatine phosphate.
E) The system of curve C enables fast-twitch fibers to generate force quickly.

Question

Refer to the graph below, showing the capacity of three systems that provide ATP for muscle contraction. Which of the following statements is true? 
A) The system of curve A metabolizes carbohydrates to pyruvate and lactate. 
B) The system of curve B comes on line within seconds but lacks sustained efficiency. 
C) The system of curve B uses ATP produced by oxidative metabolism. 
D) The system of curve C uses preformed ATP and creatine phosphate. 
E) The system of curve C enables fast-twitch fibers to generate force quickly.

Quizplus · Accepted Answer

Curve B represents the phosphagen system, which provides ATP quickly but has limited capacity and cannot sustain muscle contractions for extended periods of time. Curve A represents the glycolytic system, which metabolizes carbohydrates to produce ATP but also produces lactate as a byproduct. Curve C represents the oxidative system, which uses preformed ATP and creatine phosphate and enables slow-twitch fibers to generate force over long periods of time. Therefore, choice B is the only true statement based on the information provided in the graph.

Refer to the Graph Below, Showing the Capacity of Three