Animal and Plant Cell Differences

This lesson covers the structural differences between animal and plant cells as required by the Edexcel GCSE Combined Science specification (1SC0). You need to identify structures found in both cell types, explain the functions of structures unique to plant cells, and understand why certain structures are only found in some plant cells.

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Structures Common to Both Cell Types

Animal cells and plant cells are both eukaryotic. They share several sub-cellular structures:

Organelle	Function
Nucleus	Contains genetic material (DNA); controls cell activities
Cell membrane	Controls the passage of substances into and out of the cell
Cytoplasm	Jelly-like substance where most chemical reactions occur
Mitochondria	Site of aerobic respiration — energy is transferred from glucose
Ribosomes	Site of protein synthesis

These organelles are essential for basic cell functions — storing genetic information, carrying out chemical reactions, producing proteins and releasing energy through respiration.

Exam Tip: When asked to "compare" animal and plant cells, always state the similarities first, then clearly describe the differences. This shows the examiner you understand both cell types.

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Structures Found Only in Plant Cells

Plant cells contain three additional structures that are not found in animal cells:

Cell Wall

• Made of cellulose (a tough carbohydrate).
• Located outside the cell membrane.
• Provides structural support and protection.
• Prevents the cell from bursting (lysing) when it absorbs water by osmosis.
• The cell wall is freely permeable — it allows all molecules to pass through. It is the cell membrane that controls what enters and leaves.

Permanent Vacuole

• A large, central, fluid-filled compartment.
• Contains cell sap — a dilute solution of sugars, mineral salts and sometimes pigments.
• Maintains turgor pressure — the pressure of the cell sap pushing against the cell wall, which keeps the cell firm and supports the plant.
• When a plant cell loses too much water, the vacuole shrinks and the cell becomes flaccid (loses turgidity). The plant wilts.

Chloroplasts

• Green, disc-shaped organelles.
• Contain the pigment chlorophyll, which absorbs light energy.
• The site of photosynthesis — carbon dioxide and water are converted into glucose and oxygen.
• Not all plant cells contain chloroplasts — only cells in green parts of the plant (e.g. leaf mesophyll cells). Root cells do not photosynthesise and therefore lack chloroplasts.

graph LR
    subgraph Plant Cell Only
        A[Cell wall - cellulose]
        B[Permanent vacuole - cell sap]
        C[Chloroplasts - photosynthesis]
    end
    subgraph Both Cell Types
        D[Nucleus]
        E[Cell membrane]
        F[Cytoplasm]
        G[Mitochondria]
        H[Ribosomes]
    end

Exam Tip: A common mistake is saying that "plant cells have a cell wall instead of a cell membrane". This is wrong — plant cells have both a cell wall AND a cell membrane. The cell wall is outside the membrane.

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Comparison Table

Feature	Animal Cell	Plant Cell
Nucleus	✓	✓
Cell membrane	✓	✓
Cytoplasm	✓	✓
Mitochondria	✓	✓
Ribosomes	✓	✓
Cell wall (cellulose)	✗	✓
Permanent vacuole	✗ (may have small, temporary vacuoles)	✓ (large, central)
Chloroplasts	✗	✓ (in green parts only)
Shape	Irregular (rounded)	Regular, rectangular (due to cell wall)

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Why Do Plant Cells Need These Extra Structures?

Plants are autotrophs — they make their own food through photosynthesis. This requires chloroplasts. Because plants cannot move to find water or shelter, they need a rigid cell wall for structural support. The permanent vacuole stores dissolved substances and maintains turgor pressure, keeping the plant upright.

Turgor and Plasmolysis

When a plant cell is in a dilute solution (e.g. pure water), water moves into the cell by osmosis. The vacuole swells, pushing the cytoplasm against the cell wall. The cell becomes turgid (firm). The rigid cell wall prevents the cell from bursting.

When a plant cell is in a concentrated solution, water leaves the cell by osmosis. The vacuole shrinks and the cell membrane pulls away from the cell wall. This is called plasmolysis and the cell is said to be plasmolysed.

Exam Tip: Animal cells do not have a cell wall, so in a very dilute solution they can take in too much water and burst (lyse). Plant cells do not burst because the cell wall provides support.

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Specialised Cells

Not all animal and plant cells look the same. Many cells are specialised — their structure is adapted for a specific function. For example:

Cell	Type	Key Adaptation
Red blood cell	Animal	No nucleus — more room for haemoglobin; biconcave disc shape for large surface area
Sperm cell	Animal	Streamlined shape and tail (flagellum) for swimming; many mitochondria for energy
Root hair cell	Plant	Long, thin extension increases surface area for absorbing water and minerals
Palisade mesophyll cell	Plant	Packed with chloroplasts near the top of the leaf for maximum photosynthesis

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Summary

• Animal and plant cells both contain a nucleus, cell membrane, cytoplasm, mitochondria and ribosomes.
• Plant cells additionally have a cellulose cell wall, a permanent vacuole (containing cell sap) and chloroplasts (in green parts).
• The cell wall provides structural support and prevents the cell from bursting.
• The permanent vacuole maintains turgor pressure, keeping the cell and plant firm.
• Chloroplasts are the site of photosynthesis — not all plant cells have them.
• Animal cells have an irregular shape; plant cells have a regular, rectangular shape.
• Both cell types can be specialised for particular functions.

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Deeper Look: Specialised Plant and Animal Cells

Being able to identify a cell from its structural adaptations is a common exam skill. Each specialised cell has features that fit its particular function, and you should be able to explain how each adaptation helps the cell perform its job.

Red Blood Cells (Erythrocytes)

Red blood cells carry oxygen around the body. Their adaptations include: