BRAINCAKEPlant Growth Responses
Plants show directional growth responses which are known as tropisms. Plants are limited by the fact they cannot move but still need to respond to changes in the environment so possess chemical communication systems called hormones. Plants have evolved a range of hormones such as auxins, gibberellins, abscisic acid and ethene which have a wide range of functions within the plant.
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Key terms in this lesson
- auxin
- A plant growth hormone, produced at the tips of shoots and roots, that stimulates cell elongation, maintains apical dominance and controls tropisms.
- gibberellin
- A plant growth hormone that stimulates stem elongation, breaks seed dormancy and triggers the mobilisation of food stores during germination.
- abscisic acid
- A plant hormone that maintains dormancy and causes stomatal closure in response to water stress.
- ethene
- A gaseous plant hormone that causes fruit ripening and leaf fall (abscission).
- tropism
- A directional growth response of a plant towards or away from a directional stimulus such as light or gravity.
More in Plant Responses
- Plant Hormones
- Seed Germination
- Apical Dominance
- Gibberellins: Synergy and Antagonism.
- Leaf Loss
- Flowering and Day-Length
- Preventing Freezing
- Stomatal Control
All 19 lessons in Plant Responses · All AQA A-level Biology topics