Which of the following occurs in the stroma of the chloroplast?

• A. Light-dependent reactions
• B. Calvin cycle
• C. Glycolysis
• D. Citric acid cycle

Answer: (B)

Verified step by step guidance

1. Understand the structure of the chloroplast: The chloroplast has two main regions, the thylakoid and the stroma. The thylakoid is where light-dependent reactions occur, while the stroma is the fluid-filled space surrounding the thylakoids.
2. Review the processes listed in the question: Light-dependent reactions occur in the thylakoid membrane, glycolysis occurs in the cytoplasm of the cell, and the citric acid cycle occurs in the mitochondria. The Calvin cycle, however, takes place in the stroma of the chloroplast.
3. Recall the purpose of the Calvin cycle: It is a light-independent reaction that uses ATP and NADPH (produced during light-dependent reactions) to convert carbon dioxide into glucose through a series of enzymatic steps.
4. Understand the key steps of the Calvin cycle: The cycle includes three main phases—carbon fixation, reduction, and regeneration of RuBP (ribulose-1,5-bisphosphate). These processes occur in the stroma.
5. Conclude that the correct answer is the Calvin cycle, as it is the only process listed that occurs in the stroma of the chloroplast.