Explain how farmers and gardeners use plant hormones to their advantage in two different ways.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Plant hormones can be manufactured and applied artificially to control plant growth and development. These artificial hormones are used widely in agriculture and horticulture.
Model answer (4 marks)
1. Rooting powder contains auxin (or gibberellin) and is applied to cuttings. It stimulates root formation, so more plants can be produced quickly and the success rate of cuttings is increased. This allows farmers and gardeners to clone desirable plants.
2. High‑concentration auxin or ethylene is used in selective herbicides, and gibberellins are used to increase fruit size or delay ripening. The herbicides disrupt normal growth in weeds, killing them without damaging crops or grass. Gibberellins can enlarge fruit or allow fruit to be harvested unripe and ripened later, giving a fresher product and higher yield.
2. High‑concentration auxin or ethylene is used in selective herbicides, and gibberellins are used to increase fruit size or delay ripening. The herbicides disrupt normal growth in weeds, killing them without damaging crops or grass. Gibberellins can enlarge fruit or allow fruit to be harvested unripe and ripened later, giving a fresher product and higher yield.
Examiner tips
- Use the word ‘stimulate’ or ‘promote’ when describing hormone action.
- Give a clear example for each use (rooting powder, herbicide, fruit size).
- Show the benefit (cloning, weed control, larger fruit).
Common mistakes
- Mixing up auxin with gibberellin without specifying which is used where.
- Failing to mention the specific benefit (e.g., cloning, weed control).
- Using vague terms like ‘helps plants grow’ instead of ‘stimulates root formation’.
Mark scheme (4 marks)
- Use 1: rooting powder/hormone rooting powder contains auxin / gibberellin promotes root growth on cuttings
- Explanation of use 1: allows more plants to be produced quickly / increases success rate of cuttings / allows cloning/propagation of desirable plants
- Use 2: weedkillers / selective herbicides contain high concentrations of auxin / ethene used to ripen fruit / gibberellins used to increase fruit size or delay ripening
- Explanation of use 2: disrupts normal growth in weeds / kills weeds without harming grass or crops / fruit can be harvested unripe and ripened later for fresher produce / larger fruit increases crop yield
Key terms in this question
Related
- All Eduqas GCSE Biology revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →