During periods of strenuous exercise or prolonged fasting, glycogen stored in liver and muscle cells is depleted - VCE - SSCE Biology - Question 8 - 2007 - Paper 1
Question 8
During periods of strenuous exercise or prolonged fasting, glycogen stored in liver and muscle cells is depleted. All glucose in the blood and cells may be completel... show full transcript
Worked Solution & Example Answer:During periods of strenuous exercise or prolonged fasting, glycogen stored in liver and muscle cells is depleted - VCE - SSCE Biology - Question 8 - 2007 - Paper 1
Step 1
Identify the context: Glycogen depletion
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Answer
During intense physical activity or extended fasting, the body primarily uses glycogen for energy. Once glycogen stores are exhausted, it must rely on other energy sources.
Step 2
Assess accessible compounds
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Answer
When glycogen and glucose are depleted, the body can utilize several alternative sources for energy. The options are: lipids, DNA, starch, and proteins.
Step 3
Evaluate each option
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Answer
Lipid: Fats can be broken down into fatty acids and glycerol for energy production, making them a feasible source.
DNA: Not a primary energy source as its function is mainly genetic information storage.
Starch: While it is a polysaccharide, it must be digested first to glucose, which is likely depleted in this context.
Protein: Can be catabolized to produce energy but is typically used as a last resort due to its importance in cellular functions.
Step 4
Conclusion
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Answer
Given all considerations, lipids are the most accessible compound for glycolysis after glucose and glycogen depletion. Hence, the answer is A. lipid.
