Last reviewed: 25 October 2026
Every living thing is made of cells, and understanding them unlocks much of junior school biology, from nutrition and transport to reproduction. This guide explains the parts of plant and animal cells, how they differ, how cells are organised into larger structures and the diagrams that examiners expect learners to draw and label.
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What a Cell Is
The cell is the basic unit of life. Some organisms, such as amoeba and bacteria, are made of a single cell. Others, including plants and animals, are made of millions of cells working together. Most cells are too small to see without a microscope.
Parts of an Animal Cell
- Cell membrane: a thin layer around the cell that controls what enters and leaves.
- Cytoplasm: a jelly-like substance where most chemical reactions take place.
- Nucleus: controls the cell’s activities and contains genetic material.
- Mitochondria: where respiration releases energy from food.
- Vacuoles: small and temporary in animal cells.
Parts of a Plant Cell
A plant cell has all the parts of an animal cell, plus three more:
- Cell wall: a tough layer made of cellulose outside the membrane, giving the cell a fixed shape and support.
- Chloroplasts: contain the green pigment chlorophyll, which traps light energy for photosynthesis.
- Large central vacuole: filled with cell sap; it keeps the cell firm.
Plant and Animal Cells Compared
Plant cells usually have a regular, box-like shape because of the cell wall, while animal cells are often rounded or irregular. Plant cells have chloroplasts and a large permanent vacuole; animal cells do not. A typical exam question asks for three differences, so learn these three: cell wall, chloroplasts and large vacuole.
Using a Microscope
Learners should know the main parts of a light microscope: eyepiece lens, objective lenses, stage, mirror or light source, and coarse and fine focus knobs. Magnification = eyepiece magnification × objective magnification. An eyepiece of ×10 with an objective of ×40 gives ×400. When preparing an onion cell slide, a thin layer of onion skin is placed on a slide with a drop of iodine or water and covered gently with a cover slip to avoid air bubbles.
Specialised Cells
Cells change their structure to do particular jobs:
- Red blood cells have no nucleus and a disc shape, giving more room and surface area to carry oxygen.
- Nerve cells are long and thin to carry messages over long distances.
- Root hair cells have a long extension that increases surface area for absorbing water and minerals.
- Sperm cells have a tail for swimming.
- Palisade cells in leaves are packed with chloroplasts for photosynthesis.
Levels of Organisation
In many-celled organisms, cells are organised in levels:
- Cell: for example, a muscle cell.
- Tissue: a group of similar cells doing the same job, such as muscle tissue.
- Organ: different tissues working together, such as the heart or a leaf.
- Organ system: organs working together, such as the circulatory or digestive system.
- Organism: the whole living thing.
Drawing and Labelling Tips
Use a sharp pencil, draw clean lines without shading, make the diagram large enough to read, and draw label lines with a ruler so they touch the part named. Give the diagram a title. These small habits earn marks in practical and written work.
Revise and Practise
Draw both cells from memory, then check against your notes. Use the Grade 8 Integrated Science papers for exam practice and see the Grade 9 Integrated Science page. The exam countdown gives five free daily questions and the What to Revise report shows weak areas. Full papers with answers come with the Monthly Pass (KSh 500 by M-Pesa).