The cell is the basic unit of life. Every living organism is made of cells: from a single-celled amoeba to a human body with 37 trillion cells. WAEC Biology expects you to know the organelles in animal and plant cells, what they look like, and what they do.
Organelles common to both animal and plant cells
• Cell membrane: controls what enters and leaves the cell. Selectively permeable. • Nucleus: contains DNA (the genetic information). Controls all cell activities. Has a nuclear membrane and nucleolus inside. • Cytoplasm: jelly-like fluid where chemical reactions happen. • Mitochondria: the powerhouse: produces ATP through respiration. More mitochondria = more energy needed. • Ribosomes: manufacture proteins from amino acids (translation). • Endoplasmic reticulum (ER): rough ER carries ribosomes and transports proteins; smooth ER makes lipids.
Organelles found ONLY in plant cells
• Cell wall: rigid layer made of cellulose. Provides support and shape. • Chloroplasts: contain chlorophyll: absorb sunlight for photosynthesis. Have double membrane and grana inside. • Large central vacuole: stores water and maintains turgor pressure. Makes the plant rigid. • Plasmodesmata: channels through the cell wall connecting adjacent plant cells.
Key differences: animal vs plant
Animal cell: no cell wall, no chloroplasts, small vacuoles, has centrioles (for cell division). Plant cell: has cell wall, chloroplasts, large central vacuole, no centrioles. Memory trick: 'Plants have CCC': Cell wall, Chloroplasts, Central vacuole.
Key points
- Nucleus = control centre (DNA)
- Mitochondria = energy (ATP) production
- Chloroplasts = photosynthesis (plants only)
- Cell wall = support (plants only, made of cellulose)
- Ribosomes = protein synthesis
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WAEC tip
WAEC often asks you to draw and label a cell. Practise your diagram: label at least 6 organelles. Unlabelled diagrams score zero for that part.
Practise this
Draw a labelled diagram of a plant cell and an animal cell. Then list three differences between them in a table.
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