This guide walks through the key facts you need for GCSE: animal and plant cells, specialised cells, microscopes, and mitosis. Keep your spec open while you read and tick things off as you go.

1. Animal and plant cells – the basics

Both animal and plant cells are eukaryotic cells. That means they:

• Have a nucleus containing DNA
• Have their genetic material inside a membrane
• Contain membrane-bound organelles (little structures with specific jobs)

Animal cell structures you must know

You should be able to label and explain the function of these parts:

• Nucleus – contains genetic material (DNA) that controls the activities of the cell
• Cytoplasm – jelly-like substance where most chemical reactions happen, containing enzymes
• Cell membrane – controls what goes in and out of the cell
• Mitochondria – where aerobic respiration happens, releasing energy
• Ribosomes – where proteins are made

If the question says "name two sub-cellular structures" from an animal cell, these are your go‑to answers.

Extra structures in plant cells

Plant cells have all of the above, plus:

• Cell wall – made of cellulose; strengthens the cell and gives it support
• Chloroplasts – contain chlorophyll; where photosynthesis happens
• Permanent vacuole – filled with cell sap; helps keep the cell turgid (swollen and firm)

Exam tip:

• If they ask "How is a plant cell different from an animal cell?", mention at least two from: cell wall, chloroplasts, permanent vacuole.

2. Prokaryotic cells – bacteria

Bacterial cells are prokaryotic. Compared to eukaryotic cells they are:

• Smaller and simpler
• Do not have a true nucleus

Key structures:

• Chromosomal DNA – a single circular strand of DNA that floats freely in the cytoplasm
• Plasmids – small loops of extra DNA, carrying genes for things like antibiotic resistance
• Cell membrane – controls what enters and leaves
• Cell wall – provides support and protection (different material from plant cell walls)

Some bacteria also have:

• Flagellum (flagella) – a tail-like structure that helps the cell move

Exam tip:

• If they ask "How is a bacterial cell different from a plant cell?", say: no true nucleus, no chloroplasts, no permanent vacuole, different cell wall.

3. Specialised cells and how they link to function

You must be able to explain how certain cells are adapted to their function. Don’t just list features – say why they matter.

Sperm cell (animal)

Function: to carry the male DNA to the egg and fertilise it.

Adaptations:

• Long tail (flagellum) – helps it swim to the egg
• Lots of mitochondria – provide energy for swimming
• Streamlined head – easier to move
• Acrosome (enzymes in the tip) – helps digest through the egg cell membrane

Nerve cell (neurone)

Function: to carry electrical signals around the body.

Adaptations:

• Long axon – carries impulses over long distances
• Branched endings (dendrites) – connect to lots of other neurones
• Myelin sheath (in many neurones) – insulates the axon and speeds up the impulse

Muscle cell

Function: to contract and relax to cause movement.

Adaptations:

• Long, thin cells that can shorten
• Lots of mitochondria – provide energy for contraction
• Often form muscle fibres by joining together

Root hair cell (plant)

Function: to absorb water and mineral ions from the soil.

Adaptations:

• Long "hair" extension – increases surface area for absorption
• Thin cell wall – easier for water to enter
• Many mitochondria – for active transport of minerals

Palisade cell (plant)

Function: to carry out photosynthesis in leaves.

Adaptations:

• Packed with chloroplasts – lots of chlorophyll to absorb light
• Near the top of the leaf – receives more light
• Tall, thin shape – many can fit into a small space

Exam tip:

• When a question says "Explain how the cell is adapted", always link feature → function.
  For example: "The root hair cell has a long projection, which increases surface area so more water can be absorbed."

4. Microscopes – light vs electron

GCSE expects you to know the difference between light and electron microscopes and why we use them.

Light microscopes

• Use light and lenses to form an image
• Let us see large sub-cellular structures, like nuclei and cell walls
• Can be used to look at living cells
• Lower magnification and resolution than electron microscopes

Electron microscopes

• Use electrons instead of light
• Have much higher magnification and resolution
• Let us see small structures like mitochondria or ribosomes in more detail
• Can’t be used on living samples (vacuum needed)

Key definitions:

• Magnification – how many times bigger the image is than the real object
• Resolution – how clear the image is; the ability to distinguish between two points

Exam formula:

You must know:

> magnification = image size ÷ real size

All three values must be in the same units.

Example:

• A cell is 0.02 mm long in real life but appears 20 mm long in the image.

Convert to the same units:

• Real size = 0.02 mm
• Image size = 20 mm

Magnification = 20 ÷ 0.02 = 1000×

5. Using standard form and units

Cell sizes are tiny, so exam questions often use standard form.

Common units:

• 1 m = 1000 mm
• 1 mm = 1000 µm (micrometres)
• 1 µm = 1000 nm (nanometres)

Make sure you can convert between them. For example:

• 0.005 mm = 5 × 10⁻³ mm = 5 µm

Exam tip:

• Underline the units given in the question.
• Convert everything to the same unit before using the magnification formula.

6. Cell division – mitosis basics

GCSE focuses on mitosis – the type of cell division used for growth and repair.

Before a cell divides:

• It grows and increases the number of sub-cellular structures (like mitochondria and ribosomes)
• It duplicates its DNA, forming X-shaped chromosomes (each arm a chromatid)

During mitosis:

1. Chromosomes line up in the centre of the cell
2. The two arms of each chromosome are pulled apart to opposite ends of the cell
3. Membranes form around each set of chromosomes, forming two nuclei
4. Finally, the cytoplasm and cell membrane divide

End result:

• Two identical daughter cells, with the same number of chromosomes as the original cell

7. Stem cells – brief overview

You’ll usually meet stem cells at the end of the cell biology topic.

• Stem cells are undifferentiated cells that can divide to produce more cells of the same type, or differentiate into specialised cells
• Embryonic stem cells can turn into most types of cell
• Adult stem cells (e.g. in bone marrow) can usually form only certain types of cell

Uses (and issues):

• Can be used to replace damaged cells (e.g. in spinal injuries or diabetes)
• Ethical concerns around the use of embryonic stem cells

Exam tip:

• If a question is about "advantages" and "disadvantages" of stem cell use, mention both medical benefits and ethical concerns.

8. Quick check: exam-style questions

Try these without looking at the notes, then mark your answers.

1. Name three structures found in plant cells but not animal cells.
2. Explain one way a sperm cell is adapted to its function.
3. Describe the difference between prokaryotic and eukaryotic cells.
4. State the formula for magnification and describe what "resolution" means.
5. A cell is 0.04 mm long in real life. On the diagram, it measures 40 mm. Calculate the magnification.
6. Describe what happens during mitosis.

Answers (roughly):

1. Cell wall, chloroplasts, permanent vacuole.
2. Long tail for swimming; many mitochondria for energy; acrosome with enzymes to digest egg membrane.
3. Prokaryotic cells are smaller, simpler, and have no true nucleus; their DNA is a loop in the cytoplasm, often with plasmids.
4. Magnification = image size ÷ real size. Resolution is how clearly we can see detail – the ability to distinguish between two close points.
5. Magnification = 40 ÷ 0.04 = 1000×.
6. Chromosomes duplicate, line up in the centre, are pulled apart to opposite sides, and the cell splits into two identical daughter cells.

9. How to revise cell biology effectively

• Make one page of notes with diagrams of an animal cell, a plant cell, and a bacterial cell
• Quiz yourself on definitions (magnification, resolution, mitosis, stem cell)
• Practise calculations using past paper questions
• Explain specialised cells out loud to someone else – if you can teach it, you know it

Do a quick 10–15 minute recap of this topic every few days. Cell biology is foundation content – once it’s solid, the rest of GCSE Biology feels much less of a headache.