Cambridge O Level Biology · Syllabus 5090 · Plant Nutrition
Nitrate Ions
What is Nitrate Ions?
Mineral ions absorbed from the soil by plant roots and used as a source of nitrogen. The nitrogen is needed to make amino acids, which are used to build proteins. A shortage of nitrate ions causes poor or stunted growth, and older leaves may turn yellow. Nitrate ions are a building material, not a source of energy.
This definition is part of the Plant Nutrition chapter in Cambridge O Level Biology.
Common mistakes with Nitrate Ions
- “Nitrate ions supply the plant with energy.” Why it is wrong: energy in a plant is released by respiring carbohydrate. Nitrate contributes atoms, not energy. Say instead Nitrate ions supply nitrogen for making amino acids, and therefore proteins. A shortage causes poor or stunted growth.
Questions students ask about Nitrate Ions
Do nitrate ions give a plant energy?
No. Nitrate ions supply nitrogen, which the plant uses to make amino acids and therefore proteins. They are a building material. A plant’s energy is released by respiring the carbohydrate made in photosynthesis, and a nitrate shortage shows as poor or stunted growth rather than as a lack of energy.