IGCSE Biology glossary
Nitrate ion
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 mineral ion (NO3-) absorbed by plant roots that provides nitrogen for the synthesis of amino acids and proteins. Without sufficient nitrate, plants show stunted growth because they cannot make the proteins needed for cell growth.
What to include in an exam answer
State the pathway: nitrate ions provide nitrogen, which is used to make amino acids, which are joined to make proteins. This three-step chain is a frequent 3-mark question.
Example in context
Explain why a plant deficient in nitrate ions grows slowly (3 marks): Nitrate ions provide nitrogen for making amino acids. Without nitrate, the plant cannot synthesise enough amino acids to make proteins. Proteins are needed for growth, so growth is stunted.
Related syllabus topic
Plant nutrition