Why is it necessary for six molecules of CO\(_2\) to enter the chloroplast during photosynthesis?

• A. To produce one molecule of glucose (C\(_6\)H\(_{12}\)O\(_6\))
• B. To initiate the light-dependent reactions
• C. To generate six molecules of ATP
• D. To release six molecules of oxygen (O\(_2\))

Answer: (A)

Verified step by step guidance

1. Understand the process of photosynthesis: Photosynthesis occurs in two main stages - the light-dependent reactions and the Calvin cycle (light-independent reactions). The Calvin cycle is where carbon dioxide (CO\(_2\)) is used to synthesize glucose (C\(_6\)H\(_{12}\)O\(_6\)).
2. Recall the molecular formula of glucose: Glucose has the chemical formula C\(_6\)H\(_{12}\)O\(_6\), which means it contains six carbon atoms. These carbon atoms must come from the CO\(_2\) molecules that enter the chloroplast.
3. Determine the role of CO\(_2\) in the Calvin cycle: During the Calvin cycle, each molecule of CO\(_2\) contributes one carbon atom. To form one molecule of glucose, six carbon atoms are required, which means six molecules of CO\(_2\) are necessary.
4. Eliminate incorrect options: The light-dependent reactions do not directly require CO\(_2\), as they focus on capturing light energy to produce ATP and NADPH. Similarly, CO\(_2\) is not directly involved in generating ATP or releasing oxygen (O\(_2\)), as these processes occur during the light-dependent reactions.
5. Conclude the correct answer: The six molecules of CO\(_2\) are required to provide the carbon atoms needed to synthesize one molecule of glucose (C\(_6\)H\(_{12}\)O\(_6\)) during the Calvin cycle.