What organelle is the site of photosynthesis in plants?

1. Analyze the question The question asks which organelle in a plant cell is where photosynthesis takes place.

2. Explain the concept Photosynthesis is the process by which green plants use light energy to make food (glucose) from carbon dioxide and water:

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in the presence of light and chlorophyll)

This process needs chlorophyll, the green pigment that traps light energy. Chlorophyll is found inside special organelles called chloroplasts.

3. Step-by-step solution Let's check each option:

• A. Chloroplasts contain chlorophyll. The grana (stacks of thylakoids) carry out the light reaction, and the stroma carries out the dark reaction (Calvin cycle). This is where photosynthesis happens. ✅
• B. Ribosomes are the site of protein synthesis, not photosynthesis. ❌
• C. Cytoplasm is the jelly-like fluid where many reactions occur, such as glycolysis, but it is not the photosynthesis site. ❌
• D. Mitochondria are the site of aerobic respiration, which releases energy (ATP). They are the "powerhouse" of the cell. ❌

4. Answer The correct option is A. Chloroplasts.

5. Exam tip Match each organelle to its job:

• Chloroplast → Captures light (photosynthesis)
• Mitochondria → Makes energy (respiration)
• Ribosome → Runs protein production

Remember that chloroplasts are found only in plant cells (and algae), not in animal cells. JAMB often tests this contrast.