IGCSE Biology glossary
Mitochondrion
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
An organelle with a folded inner membrane where aerobic respiration takes place, releasing energy from glucose. Cells with high energy demands, such as muscle cells and sperm cells, contain large numbers of mitochondria.
What to include in an exam answer
The plural is 'mitochondria'. Always link it to aerobic respiration and energy release. If asked why a particular cell has many mitochondria, explain that the cell requires a lot of energy.
Example in context
Explain why sperm cells have many mitochondria (2 marks): Sperm cells need a lot of energy for movement/swimming to reach the egg, so mitochondria carry out aerobic respiration to release this energy.
Related syllabus topic
Organisation of the organism