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
- Hormone
- A chemical messenger, secreted directly into the blood by an endocrine gland, that travels to target cells and alters their activity.
- Auxin
- A plant hormone, produced mainly at shoot and root tips, that stimulates cell elongation and controls tropisms and apical dominance.
- Gibberellin
- A plant hormone that stimulates stem elongation and the breaking of seed dormancy and germination.
- Abscisic acid
- A plant hormone that maintains dormancy and causes stomatal closure in response to water stress.
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 OCR A-level Biology topics