What is the overall process of photosynthesis in terms of light-dependent reactions and the Calvin cycle?

What is the overall process of photosynthesis in terms of light-dependent reactions and the Calvin cycle?

• A. Light reactions convert light energy to chemical energy (ATP, NADPH) and split water; Calvin cycle fixes CO2 into sugar using ATP and NADPH produced.
• B. Light reactions occur in the mitochondria and produce glucose directly.
• C. Calvin cycle uses light energy to synthesize ATP.
• D. Both stages release CO2 as a waste product.

Answer: (A)

Photosynthesis happens in two linked stages. The light-dependent reactions capture light energy to power the production of ATP and NADPH and to split water, releasing oxygen as a byproduct. These reactions take place in the thylakoid membranes of chloroplasts. The Calvin cycle then uses the ATP and NADPH from the light reactions to fix carbon dioxide into sugar, a process that occurs in the stroma. Through a series of steps, CO2 is built up into glyceraldehyde-3-phosphate and ultimately converted into glucose and other carbohydrates. The crucial connection is that ATP and NADPH generated by the light reactions provide the energy and reducing power needed for carbon fixation in the Calvin cycle. Choices that place light reactions in the mitochondria, claim they produce glucose directly, or state that the Calvin cycle uses light energy to make ATP are not accurate. Photosynthesis consumes CO2 rather than releasing it, and the stages are linked by the ATP and NADPH produced in the light-dependent reactions.

Photosynthesis happens in two linked stages. The light-dependent reactions capture light energy to power the production of ATP and NADPH and to split water, releasing oxygen as a byproduct. These reactions take place in the thylakoid membranes of chloroplasts. The Calvin cycle then uses the ATP and NADPH from the light reactions to fix carbon dioxide into sugar, a process that occurs in the stroma. Through a series of steps, CO2 is built up into glyceraldehyde-3-phosphate and ultimately converted into glucose and other carbohydrates. The crucial connection is that ATP and NADPH generated by the light reactions provide the energy and reducing power needed for carbon fixation in the Calvin cycle.

Choices that place light reactions in the mitochondria, claim they produce glucose directly, or state that the Calvin cycle uses light energy to make ATP are not accurate. Photosynthesis consumes CO2 rather than releasing it, and the stages are linked by the ATP and NADPH produced in the light-dependent reactions.