Edexcel IGCSE Biology · Spec 2.2-2.4
Animal and Plant Cells
The parts of animal and plant cells, what each part does, and the features found only in plant cells.
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Animal and Plant Cells
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Explained
Animal and plant cells: eight structures worth knowing properly
A cell diagram is easy to label and surprisingly easy to lose marks on. Questions rarely ask you simply to point at the nucleus. They describe what a structure does and expect you to name it, or name it and expect you to say what it does. Eight structures are examinable, and each needs to be known both ways round.
The eight, and what each one is for
- Nucleus: contains the genetic material and controls the cell's activities.
- Cytoplasm: the jelly like material where many of the cell's chemical reactions happen.
- Cell membrane: controls what moves into and out of the cell.
- Mitochondria: where aerobic respiration takes place.
- Ribosomes: where proteins are made.
- Cell wall: a cellulose layer that supports and strengthens a plant cell.
- Chloroplast: contains chlorophyll, and is where photosynthesis happens.
- Large permanent vacuole: contains cell sap and helps keep a plant cell firm.
Five shared, three plant
A typical animal cell and a typical plant cell both have a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. The plant cell adds a cellulose cell wall, chloroplasts and a large permanent vacuole.
The word "typical" is doing something here. Not every plant cell has chloroplasts. Root cells do not, because there is no light underground, and a question that mentions roots is usually testing exactly that.
Two pairs that get confused
The cell wall and the cell membrane are not alternative names for the same thing. The membrane is present in every cell and controls what passes through it. The wall is made of cellulose, sits outside the membrane, is found in plant cells, and does a structural job rather than a controlling one.
Chloroplast and chlorophyll are also different. The chloroplast is the organelle. Chlorophyll is the green pigment inside it that absorbs light. Writing that a cell contains "chlorophylls" where you mean chloroplasts loses the mark, because the two words name different things.
What examiners say about this topic
Principal examiner reports for Edexcel International GCSE Biology show a question asking candidates to state what is meant by the term organelle. One response is recorded as gaining no credit because it did not refer to a specific function of an organelle.
That is the pattern worth taking from this topic. General statements like "it helps the cell work" earn nothing. Name the structure, then say precisely what it does: mitochondria release energy by aerobic respiration, ribosomes make proteins, chloroplasts absorb light for photosynthesis.
Linking structures to what a cell actually does
Cells that need a lot of energy tend to have many mitochondria. Cells that make a lot of protein have many ribosomes. A palisade cell near the top of a leaf is packed with chloroplasts because that is where the light arrives.
If a question gives you an unfamiliar cell and asks you to suggest its job, count the organelles it has been drawn with. That is usually the clue you are being offered.
Spec 2.2-2.4
What you need to know
- Identify the parts of animal and plant cells
- Describe the function of each part
- Compare plant and animal cells
Active recall
Quick check
Answer each question before opening the answer.
Which three structures are found in a plant cell but not an animal cell?
A cellulose cell wall, chloroplasts and a permanent vacuole.
State the function of mitochondria and ribosomes.
Mitochondria — site of aerobic respiration (release energy); ribosomes — site of protein synthesis.
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