Cell structure and organelles
Animal and plant cell structures and what each one does.
Learning objectives
What you need to be able to do
Teacher-mapped phrasing — check against the official Cambridge syllabus for exact wording.
- 2.1.1Describe and compare the structure of animal and plant cells.
- 2.1.2State the functions of the main cell structures.
6 minute read
Cell structure and organelles
Every living thing is built from cells. The differences between an animal cell and a plant cell explain much of the difference between animals and plants.
Structures in both animal and plant cells
- Cell membrane — a partially permeable barrier controlling what enters and leaves.
- Cytoplasm — the jelly-like medium where most chemical reactions happen.
- Nucleus — contains the DNA, controlling the cell's activities and inheritance.
- Mitochondria — the site of aerobic respiration, releasing energy. Cells that need a lot of energy, such as muscle cells, contain many of them.
- Ribosomes — where proteins are made.
Extra structures found only in plant cells
- Cell wall made of cellulose — rigid, freely permeable, and gives the cell its shape and support. Note it is not the same as the membrane, and it does not control what enters.
- Chloroplasts — contain chlorophyll and are the site of photosynthesis. Root cells have none, because there is no light underground.
- Permanent vacuole — a large sac of cell sap that pushes outwards, keeping the cell firm.
Why the differences matter
A plant cannot move to find food, so it makes its own by photosynthesis (chloroplasts) and needs to hold itself upright without a skeleton (cell wall and vacuole). An animal moves to find food, so it needs flexibility rather than rigidity.
Think of it like this
A plant cell is a water balloon inside a cardboard box: the vacuole pushes outwards, the rigid wall resists, and the tension between them is what keeps a stem standing up.
Worked examples
Method, step by step
A muscle cell contains far more mitochondria than a fat storage cell. Explain why.
- 1Mitochondria are the site of aerobic respiration, which releases energy.
- 2Muscle cells contract, which requires a great deal of energy.
- 3More mitochondria means more respiration and so more energy released per second.
Muscle cells need a lot of energy for contraction, and mitochondria are where aerobic respiration releases that energy, so more mitochondria are needed.
Common misconceptions
- Saying the cell wall controls what enters the cell — it is freely permeable and structural; the partially permeable *membrane* does the controlling.
- Thinking all plant cells have chloroplasts. Root cells do not, because they receive no light.
- Believing animal cells have small vacuoles "like plants". Animal cells may have small temporary vacuoles, but not the large permanent sap-filled one.
In the exam
- When asked to compare animal and plant cells, name the three plant-only structures — cell wall, chloroplasts, permanent vacuole — and give a function, not just the name.
- Link organelle number to cell function: "many mitochondria because it needs a lot of energy for..." earns the mark that simply naming mitochondria does not.