Which of the following organelles is found only in plant cells?

Step 1: Analyze the question We need the organelle that occurs only in plant cells, not in animal cells.

Step 2: Review the concept Plant and animal cells share many organelles, but plants have a few special ones:

• Cell wall (made of cellulose)
• Large permanent vacuole
• Plastids (including chloroplasts, chromoplasts and leucoplasts)

Step 3: Check each option

• A. Mitochondria: Found in both plant and animal cells. They carry out aerobic respiration, so this is not correct.
• B. Ribosomes: Found in both. They make proteins. Not correct.
• C. Lysosomes: Mainly characteristic of animal cells, and they are present in animal cells generally. In plants, the vacuole performs a similar role. Lysosomes are not an organelle found only in plants, so this is not correct.
• D. Plastids: Found only in plant cells (and some algae). Chloroplasts, which contain chlorophyll for photosynthesis, are the best-known plastids. Animal cells do not have them. Correct.

Step 4: Answer The correct option is **D.

Exam tip: To remember what is unique to plants, think "CCV": Cell wall, Chloroplasts (plastids), Vacuole (large and permanent). Anything on that list is a good candidate when a question asks what is found only in plant cells.