Overview
What you’ll learn
- Label and compare the parts of plant, animal and bacterial cells, and state what each part does.
- Explain how structure suits function in ciliated cells, root hair cells, palisade mesophyll cells, neurones, red blood cells and gametes.
- Order the levels of organisation from cell to organism with real examples.
- Rearrange and use magnification = image size ÷ actual size, in mm and µm.
- Convert between millimetres and micrometres without slipping a factor of 1000 (Supplement).
Syllabus checklist (0610)
Statements are paraphrased and grouped by tier. Core is studied by everyone; Supplement is examined on the Extended papers only.
Core — every candidate
- 2.1Describe and compare the structure of a plant cell with an animal cell: cell wall, cell membrane, nucleus, cytoplasm, chloroplasts, ribosomes, mitochondria, vacuoles.
- 2.1Describe the structure of a bacterial cell: cell wall, cell membrane, cytoplasm, ribosomes, circular DNA, plasmids.
- 2.1Identify the cell structures listed for plant, animal and bacterial cells in diagrams and images.
- 2.1Describe the functions of the cell structures listed for plant, animal and bacterial cells.
- 2.1State that new cells are produced by division of existing cells.
- 2.1State that specialised cells have specific functions: ciliated cells (movement of mucus in the trachea and bronchi), root hair cells (absorption), palisade mesophyll cells (photosynthesis), neurones (conduction of electrical impulses), red blood cells (transport of oxygen) and sperm and egg cells (reproduction).
- 2.1Describe the meaning of the terms cell, tissue, organ, organ system and organism, illustrated by syllabus examples.
- 2.2State and use the formula: magnification = image size ÷ actual size.
- 2.2Calculate magnification and size of biological specimens using millimetres as units.
Supplement — Extended candidates only
- 2.2Convert measurements between millimetres (mm) and micrometres (µm).
In 30 seconds
- 1Plant and animal cells both have a cell membrane, cytoplasm, nucleus, ribosomes and mitochondria; only plant cells have a cellulose cell wall, chloroplasts and a large permanent vacuole.
- 2A bacterial cell has no nucleus: its circular DNA floats free in the cytoplasm, often with small rings of DNA called plasmids.
- 3New cells come only from division of existing cells — there is no other source of cells.
- 4Specialised cells match structure to job: ciliated cells sweep mucus, root hair cells absorb, palisade cells photosynthesise, neurones conduct impulses, red blood cells carry oxygen, sperm and egg cells reproduce.
- 5Levels of organisation: cell → tissue → organ → organ system → organism, e.g. muscle cell → muscle tissue → heart → circulatory system → human.
- 6Magnification = image size ÷ actual size; keep units the same first, and remember 1 mm = 1000 µm (Supplement).
Notes · 1 of 5
Plant and animal cell structure
The five parts every cell shares, the three parts only plant cells have, and what each structure does.
A labelled diagram you should be able to draw from memory: an animal cell as a rounded blob with the cell membrane as its outer edge, cytoplasm filling the interior, a large nucleus, small dots for ribosomes and oval shapes for mitochondria. A plant cell is a rectangle (because of the rigid wall) with all of the same parts plus a stiff outer cellulose cell wall, green chloroplasts and one large vacuole in the middle.
| Structure | Found in | Function |
|---|---|---|
| Cell membrane | Plant, animal, bacterial | Controls which substances enter and leave the cell |
| Cytoplasm | Plant, animal, bacterial | Jelly-like fluid where most chemical reactions happen |
| Nucleus | Plant, animal | Contains DNA and controls the activities of the cell |
| Ribosomes | Plant, animal, bacterial | Site of protein synthesis |
| Mitochondria | Plant, animal | Site of aerobic respiration, releasing energy from nutrients |
| Cell wall | Plant (cellulose), bacterial (not cellulose) | Supports the cell and gives it a fixed shape; stops plant cells bursting |
| Chloroplasts | Plant only | Contain chlorophyll and absorb light energy for photosynthesis |
| Vacuoles | Plant (one large permanent vacuole) | Stores cell sap — water and dissolved substances — helping keep the cell firm |
| Circular DNA | Bacterial | Carries the genetic information, free in the cytoplasm (no nucleus) |
| Plasmids | Bacterial | Small rings of DNA that can be exchanged between bacteria |
The comparison the exam loves: both cell types have a cell membrane, cytoplasm, nucleus, ribosomes and mitochondria. A plant cell adds a cellulose cell wall, chloroplasts and a large permanent vacuole. Chloroplasts are found only in the cells of the green parts of the plant — root cells have no chloroplasts because no light reaches them.
Wherever a cell exists, it came from another cell: new cells are produced by division of existing cells. This is why a cut heals (skin cells divide to replace lost ones) and why a growing seedling gains cells by division at its root and shoot tips.
Notes · 2 of 5
Bacterial cell structure
How a bacterial cell differs from a plant or animal cell — no nucleus, circular DNA, plasmids.
A bacterial cell is far simpler than a plant or animal cell. Its parts are: a cell wall (made of a material that is not cellulose) for support and shape; a cell membrane just inside the wall controlling entry and exit; cytoplasm; ribosomes for building proteins; and genetic material that is not enclosed in a nucleus — a single loop of circular DNA in the cytoplasm, often accompanied by plasmids, which are small extra rings of DNA.
A labelled diagram to picture: a capsule shape; outermost the wall, then the membrane, then cytoplasm containing scattered ribosomes, one long tangled loop (the circular DNA) and two or three tiny circles (plasmids). There is no nucleus, no mitochondria and no chloroplasts.
Plasmids matter far beyond exams: they are the reason bacteria are so useful in biotechnology and genetic modification, because a useful human gene can be inserted into a plasmid and the bacteria will then make the human protein (Topic 17).
Notes · 3 of 5
Specialised cells
Six cells you must know, each with a structure matched to its specific function.
A specialised cell has a structure suited to one specific function. The syllabus expects you to know these six, what each one does, and one structural feature that suits the job:
| Cell | Specific function | Feature that suits the job |
|---|---|---|
| Ciliated cell | Movement of mucus in the trachea and bronchi | Cilia (hair-like projections) sweep in one rhythm; many mitochondria power them |
| Root hair cell | Absorption of water and mineral ions | Long protrusion gives a huge surface area; no chloroplasts underground |
| Palisade mesophyll cell | Photosynthesis | Packed with chloroplasts, near the top of the leaf where light is strongest |
| Neurone | Conduction of electrical impulses | Long axon carries impulses long distances; branches connect to many other cells |
| Red blood cell | Transport of oxygen | Biconcave shape gives a large surface area; contains haemoglobin; no nucleus, so more haemoglobin fits |
| Sperm and egg cells (gametes) | Reproduction | Sperm: flagellum to swim. Egg: large, stores energy for the early embryo |
In a diagram question you may be asked to identify these cells. The picture cues: ciliated cells line the airways in a sheet with hair-like tops; root hair cells sit in a root with one long extension each; palisade cells are upright blocks stuffed with dark-staining chloroplasts; neurones are star-shaped cells with very long thin fibres; red blood cells are red discs, dented in the middle.
Notes · 4 of 5
From cell to organism
Cell, tissue, organ, organ system, organism — with the syllabus examples for each step.
| Level | Meaning | Example |
|---|---|---|
| Cell | The smallest living unit | Muscle cell; palisade mesophyll cell |
| Tissue | A group of cells with similar structure, working together to do one job | Muscle tissue; mesophyll tissue in a leaf |
| Organ | A structure made of several tissues working together to do one job | The heart; the leaf |
| Organ system | A group of organs working together to do one big job | The circulatory system; the shoot system |
| Organism | All the organ systems working together | A human; a flowering plant |
Run one chain the whole way in both kingdoms. Human: muscle cell → muscle tissue → heart → circulatory system → human. Plant: palisade mesophyll cell → mesophyll tissue → leaf → shoot system → flowering plant. Exam questions often give you a jumbled list and ask you to order it from smallest to largest — always check whether the smallest item named is a cell or a tissue before you start.
Notes · 5 of 5
Magnification and size of specimens
The one equation for this topic, worked in both directions, plus the mm–µm conversion.
Drawings and micrographs are bigger than the real thing. The relationship is magnification = image size ÷ actual size, and it rearranges: actual size = image size ÷ magnification. The golden rule is to put both measurements in the same units first — usually millimetres, because a ruler measures images in mm.
Supplement: millimetres and micrometres convert by a factor of 1000: 1 mm = 1000 µm and 1 µm = 0.001 mm. So the mitochondrion above is 0.015 mm = 15 µm. Cells are usually quoted in µm: a human cheek cell is around 60 µm across, a bacterium around 1–5 µm, a chloroplast around 4 µm. If an answer in mm has an ugly number of zeros, it probably wants to be in µm.
- 1Same units
Convert the image size or the actual size so both are in mm (or both in µm).
- 2Choose the rearrangement
Asked for magnification? Divide image by actual. Asked for size? Divide image by magnification.
- 3Sanity-check
A cell should come out in µm-scale numbers; if you get 0.00006 mm, switch to µm (0.06 µm would be far too small for a cell — check your division).
Revise
Key terms
The words examiners expect you to use precisely.
- Cell membrane
- The boundary of a cell that controls which substances enter and leave.
- Nucleus
- The structure that contains the DNA and controls the activities of the cell.
- Cytoplasm
- The jelly-like contents of a cell where most chemical reactions take place.
- Mitochondrion
- The cell structure where aerobic respiration releases energy from nutrients.Plural: mitochondria.
- Ribosome
- The tiny structure in the cytoplasm where proteins are assembled.
- Chloroplast
- The plant cell structure containing chlorophyll, where photosynthesis happens.
Show 7 more key termsShow fewer key terms
- Cell wall
- The rigid outer layer of plant (cellulose) and bacterial (non-cellulose) cells that supports the cell and fixes its shape.
- Vacuole
- The large plant cell compartment storing cell sap (water and dissolved substances), keeping the cell firm.
- Plasmid
- A small ring of DNA in a bacterial cell, separate from the circular chromosome.
- Specialised cell
- A cell with a structure suited to one specific function.
- Tissue
- A group of cells with similar structure working together to carry out one function.
- Organ
- A structure made of several tissues working together to carry out one function, such as the heart or a leaf.
- Magnification
- How many times larger an image is than the actual specimen: image size ÷ actual size.Written with a × sign and no units.
Revise
Common mistakes
Where students most often lose marks in this topic — and what to do instead.
Mistake: Giving plant-only parts to animal cells.
Animal cells have no cellulose cell wall, no chloroplasts and no large permanent vacuole.
Instead: Only plant cells have all three: cell wall, chloroplasts, large permanent vacuole.
Mistake: Saying bacteria have a nucleus.
The defining feature of bacteria is that their circular DNA is NOT enclosed in a nucleus.
Instead: Bacterial DNA is free in the cytoplasm; plasmids are extra small DNA rings.
Show 10 more mistakesShow fewer mistakes
Mistake: Calling the vacuole "full of air".
The vacuole contains cell sap — a solution of water, sugars and salts.
Instead: The vacuole stores cell sap and helps keep plant cells firm (turgid).
Mistake: Putting ribosomes in charge of respiration.
Ribosomes build proteins; mitochondria carry out aerobic respiration.
Instead: Mitochondria = respiration and energy release; ribosomes = protein synthesis.
Mistake: Saying red blood cells have no nucleus "so they can carry more oxygen".
Haemoglobin carries oxygen; losing the nucleus leaves more room for haemoglobin.
Instead: No nucleus → more haemoglobin fits → more oxygen can be transported.
Mistake: Ordering tissue before cell in levels of organisation.
Tissues are built FROM cells, so the cell level comes first.
Instead: Cell → tissue → organ → organ system → organism.
Mistake: Leaving units on a magnification.
Magnification is a ratio: the units of image size and actual size cancel.
Instead: Write ×800, never "×800 mm".
Mistake: Dividing image size by actual size when asked for the actual size.
The equation rearranges; using it un-rearranged inflates the answer by the magnification.
Instead: Actual size = image size ÷ magnification.
Mistake: Converting mm to µm by dividing by 1000.
A micrometre is a thousandth of a millimetre, so there are MORE µm than mm in the same length.
Instead: 1 mm = 1000 µm: multiply mm by 1000; divide µm by 1000 to get mm (Supplement).
Mistake: Adding chloroplasts to every plant cell in a diagram.
Root cells and other underground cells have no chloroplasts — there is no light there.
Instead: Chloroplasts appear in the green, light-exposed parts of a plant.
Mistake: Saying the cell wall controls which substances enter and leave a cell.
The cellulose wall (and the bacterial wall) is freely permeable — dissolved substances pass through it easily.
Instead: The **cell membrane** is the partially permeable barrier that **controls which substances enter and leave** the cell; the wall only gives support.
Mistake: Confusing an organ with an organ system.
One organ is made of several tissues working together; an organ system is several organs working together, so the system is a level higher.
Instead: Cell → tissue (similar cells) → **organ** (different tissues) → **organ system** (group of organs) → organism.
Check yourself
Quick quiz
26 questions with instant explanations. About 5 minutes.
Question 1 of 3
- Question 1: current question
- Question 2: not answered
- Question 3: not answered
Compare plant and animal cell structures
Which structure is found in a plant cell but not in an animal cell?
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Practise
Topical questions
14 exam-style questions with model answers and mark schemes.
A set of structured and calculation questions matched to this topic, in three tiers, each with a model answer, mark scheme and examiner tip.
Practise topical questionsExam practice
Practice paper
A 30-mark paper set out like a Cambridge paper, with a separate mark scheme. Give yourself 40 min.
Question paper
Topic 2 Practice Paper
30 marks · 40 min · 5 pages
10 multiple-choice questions and structured questions with answer lines. Topic 2: cell structure in plants, animals and bacteria, specialised cells, levels of organisation, magnification calculations.
Mark scheme
PROTopic 2 Practice Paper — mark scheme
Answers · Marking points · 3 pages
Model answers with a mark for each creditworthy point — for marking at home or in class.
Which paper covers this topic?
Paper 1 / 2
Multiple choice (45 min, 40 marks)
Core and Extended versions
Paper 3 / 4
Theory, short and structured (1 h 15, 80 marks)
Core and Extended versions
Paper 5 / 6
Practical test or Alternative to Practical (40 marks)
Experimental skills
Want a full paper? Try the Paper 2-style multiple choice, Paper 4-style structured or Paper 6-style practical sets.
Questions
Frequently asked questions
Which parts do plant and animal cells share?
Five: the cell membrane, cytoplasm, nucleus, ribosomes and mitochondria. A plant cell adds three extras — a cellulose cell wall, chloroplasts and a large permanent vacuole.
How do I remember what mitochondria and ribosomes do?
Link each organelle to its verb: mitochondria release energy in respiration; ribosomes build proteins. If a question says "releases energy", think mitochondria; if it says "makes protein", think ribosomes.
What magnification calculations do I need to be able to do?
All three rearrangements of magnification = image size ÷ actual size, with both lengths in the same units. Extended candidates also convert between mm and µm (1 mm = 1000 µm). Practice with ugly numbers — real cells give answers like 0.004 mm.
Is a virus a cell?
No. A virus is a protein coat around genetic material — no cytoplasm, no membrane-bound machinery, no cell structures at all, which is why it is not classified in any kingdom and never appears in this topic’s cell diagrams.
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No. Cambridge IGCSE and Cambridge are trademarks of Cambridge University Press & Assessment. QuizQuip is independent — not affiliated with, endorsed by, or connected to Cambridge. All our notes and questions are original material written against the published 0610 syllabus.
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Topic 3: Movement into and out of cells