Where does the Calvin cycle take place in plant chloroplasts?

Where does the Calvin cycle take place in plant chloroplasts?

• A. Thylakoid membrane
• B. Nucleolus
• C. Matrix
• D. Stroma

Answer: (D)

The Calvin cycle occurs in the stroma, the fluid-filled space inside the chloroplasts surrounding the thylakoid membranes. In the stroma, CO2 is fixed into organic molecules by RuBisCO and converted into sugars using ATP and NADPH produced by the light-dependent reactions in the thylakoid membranes. The other locations don’t fit: the thylakoid membranes are where the light-driven reactions take place; the nucleolus is a region inside the nucleus; and the matrix is the interior of mitochondria.

The Calvin cycle occurs in the stroma, the fluid-filled space inside the chloroplasts surrounding the thylakoid membranes. In the stroma, CO2 is fixed into organic molecules by RuBisCO and converted into sugars using ATP and NADPH produced by the light-dependent reactions in the thylakoid membranes. The other locations don’t fit: the thylakoid membranes are where the light-driven reactions take place; the nucleolus is a region inside the nucleus; and the matrix is the interior of mitochondria.