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Q1 - Skeletal Muscle Energy Sources

Theoretical 1 Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license
Muscle Physiology

Skeletal muscle can be active over short or long times. There are several energy sources, each affecting the strength and endurance of muscles.

Energy contribution curves A-D over time, with E (Energy) on the y-axis and t (Time) on the x-axis. X marks Minutes, Y marks Hours. Curve A peaks sharply within the first minute then drops. Curve B peaks around 2-4 minutes then declines. Curve C rises slowly and plateaus at a high level over hours. Curve D rises after A and B subside and sustains at a moderate level. E = Energy, t = Time, X = Minutes, Y = Hours.

Match the corresponding curves (A-D), showing the contribution of each energy source to power generation, with the corresponding energy source (1-4):

  1. Aerobic oxidation: muscle glycogen, plasma glucose or liver glycogen
  2. Aerobic oxidation: adipose tissue triglycerides and plasma fatty acids
  3. ATP + creatine phosphate
  4. Anaerobic oxidation: muscle glycogen
Q1.1. Aerobic oxidation: muscle glycogen, plasma glucose or liver glycogen corresponds to which curve?
Q1.2. Aerobic oxidation: adipose tissue triglycerides and plasma fatty acids corresponds to which curve?
Q1.3. ATP + creatine phosphate corresponds to which curve?
Q1.4. Anaerobic oxidation: muscle glycogen corresponds to which curve?
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Question reproduced from IBO 2023, Theoretical Paper 1, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF