Plant Movements Flashcards
What are tropisms?
Directional movements which occur when a plant part grows in a particular direction thanks to cell elongation in plant tissue.
Do tropisms occur slowly or quickly?
Slowly, due to the nature of growth movement.
Why might plants grow in a particular direction?
Light, temperature, gravity, chemical or physical stimulation.
What is phototropism?
A tropism triggered by light.
How do phototropisms occur?
Photoreceptors in plant tips perceive blue light and send chemical messages that stimulate auxin production on the side of the plant that isn’t exposed to light.
What is signal transduction?
The sending of chemical messages.
How does auxin production cause a curve towards the light?
Auxins trigger cell elongation on the side of the shoot not exposed to light, creating a curve.
What is positive phototropism?
Growth towards the light.
What is negative phototropism?
Growth away from light.
What is thigmotropism?
Plant movements displayed in response to touching a solid object.
How fast is thigmotropism?
Rapid - enhanced by cells shortening and elongating on one side of a plant.
How does thigmotropism occur>
When epidermal cells respond to touch and pressure.
How do cells that touch the solid object respond?
They shorten, whilst those on the other side lengthen.
What is positive thigmotropism?
Growth of a curve towards an object.
What is negative thigmotropism?
Growth away from an object.
Give an example of negative thigmotropism.
Plant roots avoiding stones in soil during growth.
Give an example of negative thigmotropism.
Plant roots avoiding stones in soil during growth.
What is geotropism?
Tropisms in response to gravity.
What is positive geotropism?
Growth downwards due to the gravitational pull.
What is negative geotropism?
Growth away from the gravitational pull.
How is it postulated that amyloplasts effect geotropism in plant shoots?
It’s postulated that amyloplasts feel thje gravitational pull and gather on one side of a shoot in response, creating pressure.
What does this pressure cause?
Auxin production, creating upwardly curved growth.
How does amyloplast accumulation differ in roots?
It inhibits cell elongation, creating a downwards curve.
