Which of the following are reactants of the Calvin cycle?

• A. CO\(_2\), ATP, and NADPH
• B. Pyruvate, NADPH, and O\(_2\)
• C. O\(_2\), ATP, and FADH\(_2\)
• D. Glucose, NADH, and CO\(_2\)

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the Calvin cycle, which is part of photosynthesis and occurs in the stroma of chloroplasts. It is responsible for synthesizing glucose from carbon dioxide using energy from ATP and NADPH.
2. Step 2: Identify the reactants of the Calvin cycle. These include CO\(_2\) (carbon dioxide), ATP (adenosine triphosphate), and NADPH (nicotinamide adenine dinucleotide phosphate). These molecules provide the carbon and energy required for the cycle.
3. Step 3: Eliminate incorrect options by analyzing their components. For example, pyruvate and O\(_2\) are not involved in the Calvin cycle; they are associated with cellular respiration. Similarly, FADH\(_2\) and NADH are electron carriers used in respiration, not photosynthesis.
4. Step 4: Recognize that glucose is a product of the Calvin cycle, not a reactant. This helps eliminate options that list glucose as a reactant.
5. Step 5: Confirm that the correct answer is CO\(_2\), ATP, and NADPH, as these are the essential reactants required for the Calvin cycle to proceed.