IGCSE Biology glossary
Cell membrane
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
A thin, partially permeable barrier surrounding every living cell that controls which substances enter and leave. It is made of a phospholipid bilayer with embedded proteins and is present in both plant and animal cells.
What to include in an exam answer
Always call it 'partially permeable', not 'semi-permeable'. In osmosis questions, name the membrane explicitly to earn the mark.
Example in context
Explain why the cell membrane is important for osmosis (2 marks): The cell membrane is partially permeable, allowing water molecules to pass through while restricting larger solute molecules.
Related syllabus topic
Organisation of the organism