Uses of glucose from photosynthesis — AQA GCSE Biology
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Uses of glucose from photosynthesis explained
Plants produce glucose during photosynthesis, but also require nitrate ions absorbed from the soil to synthesise proteins.
Read the full explanation
Nitrate ions are taken up by root hair cells via active transport and combined with glucose to form amino acids. These amino acids are joined together to build proteins, which are essential for plant growth and the production of new cells. Consequently, a plant suffering from nitrate deficiency exhibits stunted growth due to reduced protein synthesis. Farmers use fertilisers containing nitrates to prevent these deficiencies, ensure healthy growth and improve crop yield. (Note: chlorosis is caused by magnesium deficiency, not nitrate deficiency).
Your focus
- State that plants absorb nitrate ions from the soil to synthesise amino acids and proteins.
- Explain why a deficiency in nitrate ions causes stunted growth in plants.
- Describe the role of active transport in the uptake of mineral ions by root hair cells.
Uses of glucose from photosynthesis exam tips
Marking Points
- Nitrate ions are absorbed from the soil by root hair cells, typically using active transport against a concentration gradient.
- Plants use glucose and nitrate ions to synthesise amino acids, which are then joined to form proteins.
- Proteins are essential for plant growth, cell repair and enzyme production.
- A lack of nitrate ions in the soil leads to stunted growth in plants due to reduced protein synthesis.
- Fertilisers can be added to nutrient-poor soil to provide essential nitrate ions and improve plant growth and crop yield.
Examiner Tips
- 💡When explaining nitrate deficiency, always link stunted growth specifically to a lack of proteins.
- 💡Always specify 'nitrate ions' rather than just 'nitrogen' when discussing what roots absorb from the soil.
Common Mistakes
- Attributing yellow leaves (chlorosis) to a lack of nitrates; correction: yellowing is caused by a lack of magnesium, whereas nitrate deficiency causes stunted growth.
- Stating that plants absorb nitrogen gas directly from the air; correction: plants must absorb nitrogen in the form of nitrate ions from the soil.
- Confusing nitrate ions (NO3-) with nitrite ions (NO2-); correction: plants primarily absorb and use nitrate ions from the soil to build amino acids.