Biology 5090/11 — May/June 2021

Walkthrough

This question tests whether you know the differences between plant and animal cells. Both cell types share a cell membrane, cytoplasm and a nucleus, but plant cells have three extra structures that animal cells lack: a cell wall (made of cellulose, providing support), chloroplasts (containing chlorophyll for photosynthesis) and a sap vacuole (containing cell sap).

Going through each option:

• A — cell membrane and cytoplasm are present in both cell types, so this option is wrong.
• B — all three structures (cell wall, chloroplasts, sap vacuole) are found only in plant cells. This is correct.
• C — only the cell wall is plant-specific; cell membrane and cytoplasm are in both.
• D — only chloroplasts are plant-specific; cytoplasm and nucleus are in both.

Key Takeaways

This question tests the key differences between plant and animal cells. A good way to remember them is to think about what a plant needs that an animal doesn't: a cell wall for support, chloroplasts for photosynthesis, and a sap vacuole for storage and turgor. These three structures together are the classic "plant-only" set in 5090 exams.

Common Mistakes

• Choosing C — this happens when a student knows the cell wall is plant-only but forgets that the cell membrane and cytoplasm are present in both cell types.
• Confusing the sap vacuole with the cell membrane — the vacuole is a large central plant structure, not the outer boundary.
• Forgetting that the cell membrane is a universal structure — it is present in all cells, plant and animal.

Things to Be Careful About

• The question asks for structures present in plant cells but not in animal cells. Make sure every structure in the option is plant-only, not just one of them.
• Remember that the cell wall is made of cellulose, which is a key fact that distinguishes it from the cell membrane.
• This is a recall question — there is no need to overthink it. If you remember the three plant-only structures, you can answer it quickly.