Question

review the schematic diagram of photosynthesis and the involvement of the chloroplast in this process. which statement below is accurate? a adp ⇌ atp occurs regardless of the presence of solar energy b atp and nadph are utilized in the stroma to break down water and produce hydrogen ions. c carbon dioxide is critical to the initiation of the light independent reactions occurring in the stroma. d carbon dioxide combines with water in the thylakoid membranes to produce stored chemical energy in the form of atp.

Explanation:

• Option A: The conversion of ADP to ATP (photophosphorylation) in photosynthesis requires solar energy (light - dependent reactions), so A is incorrect.
• Option B: ATP and NADPH produced in the light - dependent reactions (thylakoid membranes) are used in the stroma for the light - independent reactions (Calvin cycle) to fix carbon, not to break down water. Water is broken down in the light - dependent reactions in the thylakoid membranes, so B is incorrect.
• Option C: The light - independent reactions (Calvin cycle) in the stroma start with the fixation of carbon dioxide. So carbon dioxide is essential for initiating these reactions, and C is correct.
• Option D: Carbon dioxide is fixed in the stroma (not thylakoid membranes) during the Calvin cycle, and ATP is produced in the thylakoid membranes during the light - dependent reactions, not by the combination of carbon dioxide and water in thylakoid membranes, so D is incorrect.

Answer:

C. Carbon dioxide is critical to the initiation of the light independent reactions occurring in the stroma.