The ratio of CO₂, NADPH₂, and ATP molecules required to synthesize starch from the output of the Calvin cycle is:
Correct answer: C. 6, 12, 18
- A. 1, 2, 3
- B. 3, 6, 9
- C. 6, 12, 18
- D. 12, 24, 36
Explanation
To synthesize one molecule of glucose through the Calvin cycle, 6 molecules of CO₂, 12 molecules of NADPH₂, and 18 molecules of ATP are needed. Glucose is the monomeric unit of starch, and thus the base ratio of 6:12:18 reflects the necessary inputs for glucose formation. Starch is a polymer of glucose, indicating that the Calvin cycle's foundational ratio is essential for forming the building blocks of starch. Option C correctly identifies this ratio. The other options either underestimate or overestimate the required amounts of each molecule, reflecting a misunderstanding of the biochemical requirements for glucose and subsequent starch synthesis.
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Cellular respiration explains how cells release energy from glucose through glycolysis, the link reaction, Krebs cycle and electron transport chain. It includes ATP production, substrate-level and oxidative phosphorylation, aerobic versus anaerobic respiration, and the roles of mitochondria, oxygen and fermentation in energy transfer.
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