Topic 2.1 · Core
Plant and Animal Cell Structure
Plant and animal cells share five structures without exception, and a typical plant cell adds three more on top. Almost every mark in this section comes down to whether you can name those eight structures precisely and place each one correctly on a diagram — not whether you know that cells exist.
What both cell types have
A plant cell and an animal cell both contain a cell membrane, cytoplasm, a nucleus, ribosomes and mitochondria. Both types of cell need to control what crosses their boundary, carry out chemical reactions, build proteins, release energy, and control their own activities — and that shared list of jobs is exactly why both cells carry the same five structures. There is no shortcut version of this list worth learning instead of the real one.
Structures, and what each one actually does
| Structure | Animal cell | Plant cell | Function |
|---|---|---|---|
| Cell membrane | Present | Present, just inside the cell wall | Controls the movement of substances into and out of the cell |
| Cytoplasm | Present | Present | Where many of the cell’s chemical reactions take place |
| Nucleus | Present in a typical cell | Present in a typical cell | Contains the genetic material and controls the cell’s activities |
| Ribosomes | Present | Present | Site of protein synthesis |
| Mitochondria | Present | Present | Site of aerobic respiration, which releases energy for the cell’s activities |
| Cell wall | Absent | Present | Supports the cell and helps it keep its shape; in plants it is made of cellulose |
| Chloroplasts | Absent | Present in photosynthetic cells | Site of photosynthesis; the chlorophyll inside absorbs light energy |
| Vacuole | No large permanent vacuole | A large permanent vacuole is typical | Contains cell sap and helps support the cell when full of water |
Notice that the function column never repeats itself. That is deliberate on Cambridge’s part, not an accident of how this table happens to be laid out: the nucleus controls, the mitochondrion respires, the membrane controls movement, and the wall supports. Swapping two of these functions onto the wrong structure is the single most common way marks are lost in this unit, so it is worth reading the four bolded functions above out loud until none of them feel interchangeable.
Why the differences exist
The three plant extras are not random trivia — each one tracks how a plant cell actually lives. A plant cell is fixed in place and makes its own food, so it needs a rigid wall for support and chloroplasts to capture light. An animal cell moves around and takes in food that is already made, so a rigid wall would only get in the way, and chloroplasts would have nothing useful to do. That reasoning is also the safest way to hold the list in your head under exam pressure: ask what the cell has to do for a living, and the structures it needs follow from the answer.
How to identify a cell from a diagram or image
Use position and relationship, not the artwork style. In a plant cell, the cell wall forms the outer boundary, with the cell membrane lying immediately inside it. The nucleus usually appears as a distinct body within the cytoplasm. A large plant vacuole occupies much of the centre of the cell, pushing the cytoplasm into a thinner layer near the edge, and chloroplasts appear as smaller bodies scattered through the cytoplasm of a photosynthetic cell. Mitochondria and ribosomes may be labelled even in a diagram where they could not actually be resolved at that magnification under a light microscope — a label tells you what is present, not what is visible to the naked eye.
Shape can support an identification, but should never be the only evidence you use. A cell wall often makes plant cells look more regular, while animal cells can take on many different shapes — but “it looks rectangular” is not a biological argument, and an examiner will not accept it as one. Check for a cell wall first; it is the most decisive single piece of evidence available to you.
Qualifiers worth holding onto
Not every plant cell contains chloroplasts — a root hair cell growing underground has none, because it has no access to light and therefore no use for them. That means the absence of visible chloroplasts does not prove a cell is an animal cell; the cell wall is the stronger and more reliable piece of evidence. Likewise, “every plant cell has one large permanent vacuole” describes the typical mature-cell model, not an exceptionless rule that applies to every plant cell you could ever be shown.
Where marks are actually lost
Cell wall and cell membrane are not the same structure, and confusing them is the most frequent error in this unit. The wall gives structural support and sits outside the membrane; the membrane controls what moves into and out of the cell. A plant cell has both — having a wall never means a plant cell lacks a membrane. In the other direction, an animal cell’s outer boundary is the cell membrane only, so labelling it “cell wall” on a diagram scores nothing.
It is also worth being precise about the vacuole: the structure Cambridge is contrasting is specifically the large cell-sap vacuoleof a mature plant cell. Simply writing “it has a vacuole” is not on its own proof that a cell is a plant cell, so lean on the cell wall as your decisive piece of evidence rather than the vacuole alone.
Once you can place these eight structures with confidence, the next step is knowing how to identify a bacterial cell as well — see bacterial cell structure — because a cell wall on its own does not distinguish a plant cell from a bacterium.