What are the main components of a cell according to the Cambridge IGCSE Biology syllabus?

In the Cambridge IGCSE Biology syllabus, the main components of a cell include the cell membrane, cytoplasm, nucleus, mitochondria, and ribosomes. Plant cells also have a cell wall, chloroplasts, and a large central vacuole. Each component plays a specific role in the cell's structure and function.

How does the structure of the cell membrane contribute to its function?

The cell membrane is composed of a phospholipid bilayer with embedded proteins. This structure allows it to be selectively permeable, controlling the movement of substances in and out of the cell. The fluid nature of the membrane enables flexibility and the ability to self-repair, which is crucial for maintaining homeostasis.

What is the role of mitochondria in cell organisation?

Mitochondria are known as the powerhouses of the cell. They are responsible for producing ATP through the process of cellular respiration. This energy is essential for various cellular processes, making mitochondria crucial for the overall organisation and function of the organism.

How do plant and animal cells differ in terms of structure?

Plant and animal cells differ in several ways. Plant cells have a rigid cell wall, chloroplasts for photosynthesis, and a large central vacuole for storage and maintaining cell turgidity. In contrast, animal cells lack these structures but have centrioles involved in cell division. These differences reflect their distinct roles in the organism's life processes.

Why is the nucleus considered the control center of the cell?

The nucleus is considered the control center of the cell because it houses the cell's genetic material, DNA. This genetic information is crucial for regulating cell activities, including growth, metabolism, and reproduction. The nucleus also coordinates the synthesis of proteins, which are vital for cell function and organisation.

Why is "Saying animal cells have a cell wall." a common mistake in Cell Structure and Organisation?

Why it happens: Both have a cell membrane; students conflate them. How to avoid it: ANIMAL cells: only cell MEMBRANE (flexible). PLANT cells: cell wall (cellulose, rigid) + cell membrane (just inside the wall).

Why is "Defining mitochondria as 'powerhouse of the cell'." a common mistake in Cell Structure and Organisation?

Why it happens: It's the popular phrase. How to avoid it: Cambridge wants "site of aerobic respiration" or "releases energy from glucose". 'Powerhouse' is too vague for marks.

Why is "Confusing 'organ' with 'organ system'." a common mistake in Cell Structure and Organisation?

Why it happens: Both involve multiple tissues. How to avoid it: Organ: ONE structure (heart). Organ SYSTEM: multiple organs working together (circulatory system: heart + blood vessels + blood).

Why is "Saying plant cells have 'a vacuole' without specifying 'large permanent'." a common mistake in Cell Structure and Organisation?

Why it happens: Animal cells can have small temporary vacuoles too. How to avoid it: Specify LARGE PERMANENT (sap) vacuole for plants. Animal cells have TEMPORARY vacuoles (food vacuoles in white blood cells, contractile vacuoles in protozoa).

Organisation of the OrganismCambridge IGCSE Biology (0610)

Cell Structure and Organisation

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Cell Structure and Organisation — Cambridge IGCSE 0610 Biology Extended (2026)

What's inside a cell, what each part does, and how cells specialise. Plus the difference between animal and plant cells. Cambridge wants the FUNCTION named, not just the organelle.

What you’ll learn

Mapped to the Cambridge IGCSE 0610 syllabus (2026-2028).

2.1 — Identify and describe the structures and functions of cell organelles.
2.1 — Compare animal and plant cells.
2.1 — State the levels of organisation: cell → tissue → organ → organ system → organism.

Animal vs plant cells

Plant cells have cell wall + chloroplasts + permanent vacuole. Animal cells don't.

Both animal and plant cells have:

Cell membrane (selectively permeable barrier).
Cytoplasm (jelly-like material where reactions happen).
Nucleus (contains DNA, controls cell).
Mitochondria (respiration sites).
Ribosomes (protein synthesis).

Plant cells ALSO have (animal cells don't):

Cellulose cell wall — rigid, outside the membrane. Gives shape and support.
Chloroplasts — green organelles containing chlorophyll. Site of photosynthesis.
Large permanent vacuole — fluid-filled sac of cell sap. Provides turgor (firmness).

Drawing tips for Cambridge.

Animal cell: roughly round/blob shape, no cell wall.
Plant cell: rectangular shape (because of cell wall), label cell wall AND membrane separately.

Worked qualitative. Why are plant cells more rigid than animal cells?

Cellulose cell wall: holds shape mechanically.
Vacuole full of water: pushes outward against the wall (turgor pressure).
Together: rigid box-like shape.

Cambridge tip. When labelling diagrams, label BOTH the cell wall AND the cell membrane in plant cells — they're different structures. Many students label only one.

Animal: membrane, cytoplasm, nucleus, mitochondria, ribosomes.
Plant: ALL OF ABOVE + cell wall + chloroplasts + vacuole.
Cell wall = cellulose, RIGID, plant only.
Both have cell membrane.

Organelle functions in detail

Memorise the FUNCTION, not just the name. Cambridge mark schemes need the function.

Nucleus.

Spherical / oval; usually largest visible structure.
Surrounded by nuclear membrane.
Contains DNA arranged in chromosomes.
Controls all cell activities by directing protein synthesis.

Cell membrane.

Thin, FLEXIBLE outer boundary.
Made of lipids and proteins (a phospholipid bilayer).
SELECTIVELY PERMEABLE: lets some substances through, blocks others.
Controls what enters and leaves the cell.

Cytoplasm.

Jelly-like material filling the cell (mostly water).
Where most chemical reactions occur.
Contains organelles suspended within.

Mitochondrion.

Sausage-shaped, with double membrane.
Site of AEROBIC RESPIRATION.
Releases ENERGY from glucose (using O₂; producing CO₂ and water).
Cells with high energy demand (muscle, sperm, liver) have many mitochondria.

Ribosome.

Tiny dots; can be free in cytoplasm or attached to membranes.
Site of PROTEIN SYNTHESIS.
All cells have ribosomes (because all cells need to make proteins).

Chloroplast (plant only).

Lens-shaped, GREEN (contains chlorophyll).
Site of PHOTOSYNTHESIS.
Use light energy + CO₂ + water → glucose + O₂.

Cell wall (plant only).

Rigid outer layer of CELLULOSE fibres.
OUTSIDE the cell membrane.
Gives shape and prevents bursting.
Fully permeable (in contrast to the selectively permeable cell membrane inside).

Permanent vacuole (plant only).

Large fluid-filled sac inside cells.
Contains CELL SAP (water + dissolved substances).
Provides TURGOR PRESSURE — pressing against the cell wall, keeping the plant firm.
A wilted plant has lost vacuole pressure.

Nucleus: DNA, control.
Cell membrane: selectively permeable.
Mitochondria: respiration / energy.
Ribosome: protein synthesis.
Chloroplast: photosynthesis (plant).
Cell wall: cellulose, rigid (plant).
Vacuole: turgor (plant).

Levels of organisation

Cell → tissue → organ → organ system → organism. Each level builds on the one below.

Five levels (smallest to largest).

1. Cell. Single unit. Carries out all life processes (in a single cell organism) or a specialised role (in a multicellular organism).

2. Tissue. A group of SIMILAR cells working together for a shared function.

Muscle tissue: cells that contract.
Xylem tissue: dead, hollow cells transporting water in plants.
Epithelial tissue: lining cells (gut wall, skin surface).

3. Organ. A structure made of DIFFERENT tissues working together.

Heart: muscle tissue + connective tissue + nervous tissue + blood vessels — all working to pump blood.
Leaf: epidermis + palisade mesophyll + spongy mesophyll + xylem + phloem — all working to photosynthesise.
Kidney: many tissue types working to filter blood.

4. Organ system. A group of organs working together for a major function.

Digestive system: mouth + oesophagus + stomach + intestines + liver + pancreas.
Circulatory system: heart + blood vessels + blood.
Respiratory system: lungs + trachea + diaphragm.

5. Organism. A whole living thing — combination of organ systems working together.

Worked qualitative. "Is the eye a cell, tissue, organ, or organ system?" The eye contains DIFFERENT tissues (lens, retina, cornea, muscles, blood vessels) working together — so it's an ORGAN.

Worked qualitative. Place the following in order: muscle cell, leg, leg muscle (biceps), human, muscular system. Cell → tissue (muscle tissue / biceps belly) → organ (a single muscle like biceps) → organ system (muscular system) → organism (human).

Cell → tissue → organ → organ system → organism.
Tissue: similar cells.
Organ: different tissues.
Organ system: different organs.
Each level integrates the one below.

How it’s examined

Cell structure appears every Paper 2 (3-5 marks: label diagram, state functions) and Paper 4 (5-7 marks: distinguish animal/plant, link to specialised cells). Examiner reports flag students stating only the name of an organelle without its function, and confusing cell wall with cell membrane.

Sources: Cambridge IGCSE Biology 0610 syllabus 2026-2028 (2.1); 0610/22 May/Jun 2024 — Q4 (cell structure); 0610 Examiner Reports 2022-2024. Last reviewed 2026-05-07.

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Step-by-step worked examples — Cell Structure and Organisation

Step-by-step solutions to past-paper-style questions on cell structure and organisation, written exactly the way a tutor would explain them at the board.

1Compare animal and plant cells
Core• cell structure
Question
List THREE structures found in plant cells but NOT in typical animal cells, and give the function of each.
Step-by-step solution
1. Step 1
  Cellulose cell wall: rigid, gives shape and support to the cell.
2. Step 2
  Chloroplasts: contain chlorophyll, site of photosynthesis.
3. Step 3
  Large permanent vacuole (sap vacuole): contains cell sap, helps maintain turgor pressure for support.
Answer
Cell wall (support), chloroplasts (photosynthesis), large permanent vacuole (turgor / storage).
2Match organelles to functions
Core• Adapted from 0610/22 May/Jun 2024 Q4• organelles
Question
State the function of: (a) nucleus, (b) mitochondrion, (c) ribosome, (d) cell membrane.
Step-by-step solution
1. Step 1
  (a) Nucleus: contains the DNA / genetic material; controls the activity of the cell.
2. Step 2
  (b) Mitochondrion: site of (aerobic) respiration; releases energy from glucose.
3. Step 3
  (c) Ribosome: site of protein synthesis.
4. Step 4
  (d) Cell membrane: controls what enters and leaves the cell (selectively permeable).
Answer
Nucleus → DNA / control. Mitochondrion → respiration / energy. Ribosome → protein synthesis. Cell membrane → controls movement of substances.
Examiner tip
"Powerhouse" alone isn't enough for mitochondria — Cambridge wants "site of (aerobic) respiration" or "releases energy".
3Order the levels of organisation
Core• organisation
Question
Place these in order from smallest to largest: organ, tissue, organism, cell, organ system.
Step-by-step solution
1. Step 1
  Cells (smallest) → tissues (groups of similar cells with a function) → organs (different tissues working together) → organ systems (organs cooperating) → organism (whole living thing).
Answer
Cell → tissue → organ → organ system → organism.

Key Definitions and Keywords — Cell Structure and Organisation

Definitions to memorise and the exact keywords mark schemes credit for cell structure and organisation answers — sharpened from recent examiner reports for the 2026 0610 sitting.

Cell
Examiner keyword
The basic unit of life — the smallest structure capable of independent life processes.
Nucleus
Membrane-bound structure containing DNA; controls cell activity.
Cytoplasm
Jelly-like substance inside the cell membrane where most chemical reactions take place; contains organelles.
Cell membrane
Examiner keyword
Selectively permeable layer that controls what enters and leaves the cell.
Mitochondrion
Organelle where aerobic respiration takes place; releases energy from glucose.
Ribosome
Tiny organelle where protein synthesis occurs.
Chloroplast
Organelle containing chlorophyll; site of photosynthesis (plant cells only).
Permanent vacuole
Large fluid-filled sac in plant cells containing cell sap; provides turgor pressure for support.
Cellulose cell wall
Rigid outer layer of plant cells made of cellulose; gives shape and support.
Tissue
Examiner keyword
A group of cells with similar structures, working together to perform a shared function.
Example
Muscle tissue, xylem tissue, epithelial tissue.
Organ
Examiner keyword
A structure made up of different tissues working together to perform specific function(s).
Example
Heart, leaf, kidney.
Organ system
A group of organs working together to perform a specific function.
Example
Digestive system: mouth, oesophagus, stomach, intestines, etc.

Common Mistakes and Misconceptions — Cell Structure and Organisation

The traps other students keep falling into on cell structure and organisation questions — taken from recent Cambridge IGCSE 0610 examiner reports and mark schemes — and how to avoid them.

✕Saying animal cells have a cell wall.
Why it happens
Both have a cell membrane; students conflate them.
How to avoid it
ANIMAL cells: only cell MEMBRANE (flexible). PLANT cells: cell wall (cellulose, rigid) + cell membrane (just inside the wall).
✕Defining mitochondria as 'powerhouse of the cell'.
Why it happens
It's the popular phrase.
How to avoid it
Cambridge wants "site of aerobic respiration" or "releases energy from glucose". 'Powerhouse' is too vague for marks.
✕Confusing 'organ' with 'organ system'.
Why it happens
Both involve multiple tissues.
How to avoid it
Organ: ONE structure (heart). Organ SYSTEM: multiple organs working together (circulatory system: heart + blood vessels + blood).
✕Saying plant cells have 'a vacuole' without specifying 'large permanent'.
Why it happens
Animal cells can have small temporary vacuoles too.
How to avoid it
Specify LARGE PERMANENT (sap) vacuole for plants. Animal cells have TEMPORARY vacuoles (food vacuoles in white blood cells, contractile vacuoles in protozoa).

Practice questions

Exam-style questions with step-by-step worked solutions. Try one before checking the method.

Past paper style quiz

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Cell Structure and Organisation — frequently asked questions

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Cell Structure and Organisation

Short Study Notes in the form of Slides

Detailed Study Notes

What you’ll learn

How it’s examined

1Compare animal and plant cells

2Match organelles to functions

3Order the levels of organisation

Cell

Nucleus

Cytoplasm

Cell membrane

Mitochondrion

Ribosome

Chloroplast

Permanent vacuole

Cellulose cell wall

Tissue

Organ

Organ system

✕Saying animal cells have a cell wall.

✕Defining mitochondria as 'powerhouse of the cell'.

✕Confusing 'organ' with 'organ system'.

✕Saying plant cells have 'a vacuole' without specifying 'large permanent'.

Practice questions

Past paper style quiz

Assess your understanding

Cell Structure and Organisation — frequently asked questions