In eukaryotic plant cells, where does photosynthesis primarily occur?

• A. In the mitochondrion, primarily on the inner mitochondrial membrane
• B. In the chloroplast, mainly in the thylakoid membranes (light reactions) and stroma (Calvin cycle)
• C. In the cytosol, where chlorophyll captures light energy
• D. In the nucleus, where photosynthetic genes are transcribed

Answer: (B)

Verified step by step guidance

1. Identify the organelle responsible for photosynthesis in eukaryotic plant cells. Photosynthesis occurs in the chloroplast, which is a specialized organelle.
2. Understand the structure of the chloroplast, which contains thylakoid membranes and stroma. The thylakoid membranes are where the light-dependent reactions take place.
3. Recognize that the light-dependent reactions capture light energy using chlorophyll and convert it into chemical energy (ATP and NADPH) in the thylakoid membranes.
4. Know that the Calvin cycle, or light-independent reactions, occurs in the stroma of the chloroplast, where ATP and NADPH are used to fix carbon dioxide into glucose.
5. Conclude that photosynthesis primarily occurs in the chloroplast, with light reactions in the thylakoid membranes and the Calvin cycle in the stroma, not in mitochondria, cytosol, or nucleus.