Learning objectives
- Draw and label a typical plant cell
- State the function of each organelle
- List three differences between plant and animal cells
1. The three plant-only structures
The cell wall is made of cellulose. It is rigid and fully permeable, giving the cell its fixed shape and preventing bursting when water enters by osmosis.
Chloroplasts contain chlorophyll and are the site of photosynthesis. The large central vacuole stores cell sap and, when full, presses the cytoplasm against the wall to create turgor pressure — the reason a well-watered plant stands upright.
- Cell wall — cellulose, rigid, fully permeable, mechanical support
- Chloroplast — contains chlorophyll, traps light energy
- Central vacuole — stores sap, maintains turgidity
2. Structures shared with animal cells
The nucleus controls all cell activities and carries DNA. Mitochondria release energy by aerobic respiration. Ribosomes make protein, the endoplasmic reticulum transports materials, and the Golgi body packages and secretes them.
The plasma membrane is partially permeable and controls what enters and leaves — remember: the wall is fully permeable, the membrane is partially permeable. That distinction is a very common exam trap.
3. Turgor, plasmolysis and wilting
In pure water the vacuole fills and the cell becomes turgid. In a strong salt or sugar solution water leaves by osmosis, the cytoplasm shrinks away from the wall, and the cell is said to be plasmolysed. At field scale this is exactly what wilting looks like — and why a root-rot or vascular-wilt pathogen produces the same visible symptom as drought.
Key definitions
- Turgor pressure
- Pressure of the vacuole contents pushing the cytoplasm against the cell wall.
- Plasmolysis
- Shrinking of the cytoplasm away from the cell wall due to water loss by osmosis.
- Organelle
- A specialised structure inside a cell that performs a specific function.
Exam tips
- Always use a sharp pencil, single clean lines and horizontal label lines with no arrowheads.
- If asked for differences, answer in pairs (plant has X, animal has none) — never list only the plant feature.
Practice exam questions & model answers
Q1.State three structural differences between a plant cell and an animal cell.
A plant cell has a cellulose cell wall while an animal cell has only a plasma membrane; a plant cell has chloroplasts while an animal cell has none; a plant cell has one large central vacuole while an animal cell has small, temporary vacuoles or none.
Q2.Why does a plant cell not burst when placed in distilled water?
The rigid cellulose cell wall resists further expansion once the cell is fully turgid, so inward pressure balances the osmotic uptake of water and the cell cannot burst.
Q3.Distinguish between the cell wall and the plasma membrane.
The cell wall is non-living, made of cellulose and fully permeable, providing support. The plasma membrane is living, made of lipids and proteins, and is partially permeable, controlling movement of substances into and out of the cell.
Continue revising
Photosynthesis: Process, Equation and Limiting Factors
BotanyLeaf Structure, Stomata and Transpiration
Agricultural SciencePlant Nutrition, NPK and Soil Fertility
Plant PathologyPlant Pathology Basics: Pathogens, Disease Triangle and Koch's Postulates
Put the theory to work — diagnose a real leaf photo or browse the disease library.