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
Lesson video
Loading...
Prior knowledge starter quiz
6 Questions
Q1.True or false? Only animals have hormones.
Q2.What is the process by which plants make their own food?
Q3.Match the parts of this plant to their description.
reproductive organ
provides support and contains tissues that transport sugars and water
where most photosynthesis takes place
where minerals and ions are absorbed
Q4.What is the name of the tissue in plants where cells grow and elongate?
Q5.Which of the following is true about hormones?
Q6.How do plants grow in height and width?
Assessment exit quiz
6 Questions
Q1.What do plant hormones do?
Q2. are growth responses to stimuli in plants that provide a survival advantage.
Q3.When discussing tropisms, select the correct statements.
Q4.Which tropism is the plant root below displaying?
Q5.Which direction is light coming from and which side of the shoot is auxin most abundant?
