Exam Frequency Analysis
Past paper frequency (2018 to 2024)
This topic accounts for approximately 18% of your exam marks.
stable
Very High
Stable18%
Cell structure and organelle function appear on nearly every paper; one of the highest-frequency topics.
A side-by-side comparison
| Feature | Animal cell | Plant cell |
|---|---|---|
| Nucleus | Yes | Yes |
| Cytoplasm | Yes | Yes |
| Cell membrane | Yes | Yes |
| Mitochondria | Yes | Yes |
| Ribosomes | Yes | Yes |
| Cell wall | No | Yes (cellulose) |
| Chloroplasts | No | Yes (in leaf and stem cells) |
| Permanent vacuole | No (only small temporary vacuoles) | Yes, large and central |
| Overall shape | Irregular, flexible | Fixed shape (rectangular or "box-like") because of the cell wall |
| Storage carbohydrate | Glycogen | Starch (in roots and tubers) or sucrose (in fruit) |
Why plants have what they have
Plants need three extra structures that animals do not:
- A cell wall: plants do not have a skeleton, so each individual cell has to be rigid. The cellulose wall gives the plant body its shape and stops the cell from bursting when water rushes in.
- Chloroplasts: plants make their own food by photosynthesis, so they need an organelle that contains chlorophyll to capture light energy. Animals are heterotrophs and eat ready-made food, so they have no need for chloroplasts.
- A large permanent vacuole: plants control their support hydraulically. A full vacuole pushes outwards on the cell wall, making the cell turgid and keeping the plant standing up. When the vacuole loses water, the cell becomes flaccid and the plant wilts.
