Auxins, phototropism and gravitropism
I can explain how hormones called auxins cause plant shoots and roots to respond to light and gravity.
Auxins, phototropism and gravitropism
I can explain how hormones called auxins cause plant shoots and roots to respond to light and gravity.
Lesson details
Key learning points
- Hormones control growth and development in plants, and enable plants to respond to some environmental factors.
- Auxins are plant hormones that control tropisms, which are growth responses in plants that provide a survival advantage.
- Phototropism in a shoot: auxins build up on the shaded side and cause cell elongation, so it bends towards the light.
- Gravitropism in a shoot: auxins build up on the lower side and cause cell elongation, so it bends upwards.
- Gravitropism in a root: auxins build up on the lower side but this stops cell elongation, so it bends downwards.
Keywords
Hormone - chemicals released by plants that regulate their growth
Auxins - control the growth of plants by promoting cell division and elongation in plant cells
Tropism - a plant growth response to a stimulus, it can be positive (towards) or negative (away from)
Phototropism - a plant growth response towards or away from light
Gravitropism - a plant growth response towards or opposite the direction of gravity
Common misconception
Pupils may think that plants move towards the sun, rather than grow in that direction. Pupils may also think that plants are not living.
Plants grow in a certain direction through mitosis (in meristem) and elongation. Plants are living as they carry out the common processes of living organisms.
Equipment
None required.
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
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Starter quiz
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reproductive organ
provides support and contains tissues that transport sugars and water
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where minerals and ions are absorbed
Exit quiz
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