By Thread Academy · 10 September 2026 · Biology
Plant cells and animal cells share most of their machinery — both have a nucleus, cytoplasm, cell membrane, mitochondria, and ribosomes — but they are not identical. Plant cells carry three extra structures that animal cells lack, and each one reveals something about what it means to be a plant.
Describing a typical animal cell
Picture an animal cell under a light microscope. You would see a roughly round or irregular blob, bounded by a thin cell membrane. Inside, the large dark nucleus usually stands out first, with the jelly-like cytoplasm filling the rest. At this magnification the mitochondria are just tiny threads or dots, and ribosomes are far too small to see at all. That is worth remembering: exam diagrams often simplify or exaggerate, and "what you can see under a light microscope" is a favourite exam distinction.
The membrane deserves special attention. It is not a rigid wall — it is a flexible boundary that lets the cell change shape and, in some cells, move. White blood cells, for example, engulf invading bacteria by changing shape and wrapping their membrane around them. That flexibility would be impossible with a stiff outer wall, which is one reason animal cells do not have one.
The three plant-only structures
Plant cells contain three structures that animal cells do not. Each one solves a problem that plants, being rooted in place and feeding by photosynthesis, must solve.
The cell wall
Outside the cell membrane, plant cells have a rigid cell wall made of cellulose. It gives the cell its fixed, regular shape — often drawn as a rectangle with straight edges — and it provides strength and support. When water enters a plant cell by osmosis, the cell swells against the wall, becoming turgid. This pressure keeps stems upright and leaves spread out to catch light. Without the wall, plant cells would burst from the water pressure, and land plants could not support themselves.
Chloroplasts
Chloroplasts are the sites of photosynthesis. They contain chlorophyll, the green pigment that absorbs light energy, and they use it to power the reaction that builds glucose from carbon dioxide and water. A leaf cell in bright light can contain dozens of chloroplasts. Animal cells have no need for them — animals get their energy by eating other organisms, not by capturing sunlight.
The permanent vacuole
Plant cells contain a large permanent vacuole: a sac filled with cell sap, a solution of sugars, salts, and pigments. It has three jobs worth knowing. It stores dissolved substances and can store waste. It pushes the cytoplasm against the cell wall, helping to keep the cell turgid. And it keeps the cell from drying out by acting as a water reserve. Animal cells may have small temporary vacuoles, but they do not have a single large permanent one.
Side-by-side comparison
Here is the comparison laid out plainly, which is exactly how exam mark schemes like to see it:
Structures found in both: nucleus, cytoplasm, cell membrane, mitochondria, ribosomes. Same jobs in both cell types.
Structures only in plant cells: cell wall (strength, support, regular shape), chloroplasts (photosynthesis), permanent vacuole (storage, turgor, water reserve).
Shape: animal cells are typically irregular or rounded because they lack a rigid wall; plant cells are typically regular and rectangular in diagrams because the cell wall fixes their shape.
The key exam skill is not just listing the differences but explaining them. "Plants have chloroplasts" earns a mark; "plants have chloroplasts because they photosynthesise, while animals obtain energy by feeding" earns both.
Specialised cells: structure matches function
One of the most beautiful patterns in biology is that a cell's structure fits its job. Two examples you should know well:
The root hair cell
Root hair cells absorb water and mineral ions from the soil. To do this efficiently, they are specialised in two ways. First, each cell has a long, thin root hair — a projection that enormously increases the surface area exposed to the soil, so more water and ions can be absorbed at once. Second, they contain many mitochondria. That is because absorbing mineral ions often means moving them against a concentration gradient — from soil where they are scarce into the root where they are already concentrated — and that process, active transport, needs energy. The mitochondria supply it.
The red blood cell
Red blood cells carry oxygen around the body, and their structure is stripped down for the task. They have no nucleus, which leaves more room for haemoglobin, the red pigment that binds oxygen. They are biconcave discs — flattened with a thinner centre — which gives a large surface area relative to their volume, so oxygen diffuses in and out quickly, and lets them squeeze through narrow capillaries. No other cell in the body looks quite like one, and that is the point.
Worked example: the "explain the adaptation" question
Try this exam-style question: A student observes that leaf cells near the top of a leaf contain more chloroplasts than cells deeper inside. Suggest why.
A good answer links structure to function in two steps. First, chloroplasts carry out photosynthesis, which needs light energy. Second, the cells near the top receive the most light, so placing more chloroplasts there maximises the rate of photosynthesis. Adapters of cells — and of whole tissues — are placed where they are needed. Notice that the question never used the word "adaptation," but it is testing exactly that idea: structure matched to function by position.
Another classic: Explain why a plant cell can absorb water by osmosis without bursting, while an animal cell placed in pure water might burst. The answer is the cell wall. In the plant cell, water enters, the vacuole swells, and the cell pushes against the rigid cellulose wall — pressure builds, but the wall holds, and the cell becomes turgid instead of bursting. The animal cell has only a flexible membrane, so with no wall to resist the swelling, it can rupture. One structure, two very different outcomes.
Key takeaways
- Animal and plant cells share the nucleus, cytoplasm, cell membrane, mitochondria, and ribosomes.
- Only plant cells have a cell wall (cellulose; strength, shape, and turgor), chloroplasts (photosynthesis via chlorophyll), and a permanent vacuole (storage, turgor, water reserve).
- In comparisons, always link each difference to the plant's or animal's way of life — that is what earns full marks.
- Specialised cells show structure matched to function: root hair cells have a huge surface area and many mitochondria for active transport; red blood cells have no nucleus and a biconcave shape for efficient oxygen transport.
- When answering "suggest why" questions, connect the structure to its function and the cell's location or role in one clear chain of reasoning.