Animal, plant and fungal cells are all eukaryotic, so the differences between them are smaller than students expect. The more interesting cases are the ones that break the pattern completely — cells with no nucleus at all, and cells so big you can see them without a microscope.
📚 What you need to know
Animal, plant and fungal cells share all the main organelles; they differ mainly in walls, plastids and vacuoles.
Plant walls are cellulose; fungal walls are chitin; animal cells have no wall.
Some cells are atypical — they do not fit the standard description of a cell.
Striated muscle fibres are very large and have many nuclei in one membrane.
Aseptate fungal hyphae are long threads with many nuclei and no dividing walls between them.
Giant algae such as Acetabularia are single cells several centimetres long.
Red blood cells and phloem sieve tube elements lose their nucleus as they mature.
These cases mean cell theory is qualified, not rejected.
Animal, plant and fungal cells
Start with what they share, because that is most of it: plasma membrane, cytoplasm, nucleus, mitochondria, ER, Golgi, ribosomes, vesicles. Now the differences.
Fungal cells have a wall and often a vacuole, which makes them look plant-like at a glance. The absence of chloroplasts is the giveaway — fungi cannot photosynthesise.
Feature
Animal
Plant
Fungal
Cell wall
None
Cellulose
Chitin
Chloroplasts
None
Present in cells that get light
None
Vacuole
Small and temporary
One large permanent one
Often present, smaller
Nutrition
Heterotrophic, takes in food
Autotrophic, makes food
Heterotrophic, absorbs digested food
Stored carbohydrate
Glycogen
Starch
Glycogen
Centrioles
Present
Absent in flowering plants
Absent in most
Fungi are heterotrophs, but they feed differently from animals. They release enzymes onto their food, digest it outside the body, and then absorb the small molecules. That is why a fungal cell has a wall but no chloroplast — it needs support and protection, not a way of making sugar.
Cells that break the rules
The standard description of a cell is: one nucleus, one plasma membrane, small enough to need a microscope. Several real cells ignore parts of that.
The muscle fibre and the hypha break the same rule in different ways: both are one continuous piece of cytoplasm containing many nuclei.
Atypical cell
What is unusual
Why it is like that
Striated muscle fibre
Up to 30 cm long, with many nuclei sharing one plasma membrane
It forms when many cells fuse together, so contraction can be coordinated along the whole fibre
Aseptate fungal hyphae
Long threads of cytoplasm with many nuclei and no cross walls
Materials can flow freely along the thread, which helps the fungus spread and feed quickly
Giant algae, such as Acetabularia
A single cell several centimetres long, visible without a microscope
It shows a cell does not have to be microscopic to work
Red blood cells
No nucleus and no mitochondria in mature cells
More room for haemoglobin, and they do not use up the oxygen they carry
Phloem sieve tube elements
Lose the nucleus and most organelles as they mature
Leaves a clear tube for sap to flow through; a companion cell keeps them alive
The pattern to notice. Every atypical cell is unusual for a reason connected to its job. Muscle fuses so it contracts as one unit. Red blood cells drop the nucleus to carry more oxygen. Hyphae skip the cross walls so material moves freely. If you can give the reason as well as the oddity, you are answering at the level the question wants.
What this means for cell theory
An exam question will sometimes ask whether these examples disprove cell theory. They do not, and the reasoning matters more than the answer.
Cell theory is supported by an enormous number of observations across every kingdom.
A handful of exceptions shows the theory does not describe every case perfectly.
So the theory is qualified — kept, with the exceptions noted — rather than rejected.
This is normal in science. Theories get refined by awkward evidence far more often than they get replaced.
🧠
Which rule is broken?
Muscle and hyphae break one nucleus per cell. Giant algae break cells are microscopic. Red blood cells and sieve tubes break every cell has a nucleus. Sort them by the rule and you will never mix them up.
Worked examples
WE 1
Distinguish a plant cell from a fungal cell
State two features that could be used to distinguish a plant cell from a fungal cell. (2 marks)
Feature 1: the wall
A plant cell wall is made of cellulose, while a fungal wall is made of chitin.
Feature 2: chloroplasts
Plant cells exposed to light contain chloroplasts; fungal cells never do.
Cellulose versus chitin, and chloroplasts present versus absent“cell wall present” is not a difference — both have one, so name the material
WE 2
Explain an atypical cell
Striated muscle fibres contain many nuclei within a single plasma membrane. Explain how this arises and why it is useful. (3 marks)
Point 1: how it forms
Many separate cells fuse together during development, keeping all their nuclei.
Point 2: the result
This produces one very long fibre with a single continuous cytoplasm.
Point 3: why it helps
The whole fibre can be controlled and contract as one unit, and many nuclei can supply enough mRNA for a cell that size.
Fusion of many cells, giving one long fibre that contracts together“explain” wants the reason, so an oddity without a purpose scores badly
WE 3
Discuss the effect on cell theory
Discuss whether atypical cells such as giant algae disprove cell theory. (3 marks)
Point 1: what they show
Giant algae are single cells several centimetres long, so not all cells are microscopic as usually described.
Point 2: the other side
They still have a plasma membrane, cytoplasm, DNA and ribosomes, so they fit the main claims of cell theory.
Point 3: the judgement
The theory is therefore qualified rather than disproved, because the weight of evidence still supports it.
Exceptions refine the theory; they do not overturn it“discuss” means give both sides and then reach a clear judgement
💡 Exam tips
Name wall materials: cellulose for plants, chitin for fungi, peptidoglycan for bacteria.
Learn one atypical example for each broken rule, with a reason attached.
Say qualified, not disproved, when discussing exceptions.
Red blood cells lose the nucleus and the mitochondria — the second point is often forgotten.
Use the term aseptate for hyphae with no cross walls.
If asked for differences, give both sides of each one.
⚠ Common mistakes
Saying fungi have chloroplasts. They are heterotrophs and cannot photosynthesise.
Writing that plant cells have no mitochondria. Every plant cell respires.
Saying atypical cells prove cell theory wrong. They qualify it.
Calling a muscle fibre many cells. It is one cell containing many nuclei.
Claiming all cells are microscopic. Giant algae and muscle fibres are not.
Forgetting that sieve tube elements need a companion cell to survive without a nucleus.
Up next: Cell Types & Structures (Skills) — how to work out what kind of cell you are looking at, and how to link a structure to the job it does.
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