Questions: Where does the Calvin cycle take place? Select one: a. chlorophyll molecule b. cytoplasm surrounding the chloroplast c. thylakoid membrane d. outer membrane of the chloroplast e. stroma of the chloroplast

The answer is the last one (e): stroma of the chloroplast.

Explanation for each option:

a. Chlorophyll molecule: Incorrect. Chlorophyll is a pigment involved in capturing light energy during the light-dependent reactions of photosynthesis, not where the Calvin cycle occurs.

b. Cytoplasm surrounding the chloroplast: Incorrect. The cytoplasm is the fluid outside the chloroplasts in the cell, and the Calvin cycle takes place inside the chloroplast.

c. Thylakoid membrane: Incorrect. The thylakoid membrane is where the light-dependent reactions of photosynthesis occur, not the Calvin cycle.

d. Outer membrane of the chloroplast: Incorrect. The outer membrane is part of the chloroplast's boundary and does not host the Calvin cycle.

e. Stroma of the chloroplast: Correct. The Calvin cycle, also known as the light-independent reactions or dark reactions, takes place in the stroma of the chloroplast, where it uses ATP and NADPH produced in the light-dependent reactions to fix carbon dioxide into glucose.

In summary, the Calvin cycle occurs in the stroma of the chloroplast.