Which of the following is an input required for the Calvin cycle (light-independent reactions) in photosynthesis?

• A. CO\(_2\), ATP, and NADPH
• B. H\(_2\)O, ADP, and NADP\(^+\)
• C. Glucose, NADH, and CO\(_2\)
• D. O\(_2\), ATP, and FADH\(_2\)

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the Calvin cycle, which is the light-independent reaction in photosynthesis. It occurs in the stroma of chloroplasts and uses energy from ATP and NADPH produced during the light-dependent reactions to convert CO\(_2\) into glucose.
2. Step 2: Identify the key inputs required for the Calvin cycle. These include CO\(_2\) (as the carbon source), ATP (as the energy source), and NADPH (as the reducing agent providing electrons).
3. Step 3: Analyze the options provided in the question. Compare each set of inputs to the known requirements of the Calvin cycle.
4. Step 4: Eliminate incorrect options. For example, H\(_2\)O, ADP, and NADP\(^+\) are outputs of the light-dependent reactions, not inputs for the Calvin cycle. Similarly, glucose is a product of photosynthesis, not an input, and NADH and FADH\(_2\) are involved in cellular respiration, not photosynthesis.
5. Step 5: Select the correct answer based on the inputs required for the Calvin cycle: CO\(_2\), ATP, and NADPH.