CGP - Plant and Animal Responses Flashcards
Define tropism.
The response of a plant to a directional stimulus.
What is a positive vs negative tropism?
Positive - towards the stimulus
Negative - away from the stimulus
What is phototropism?
The growth of a plant in response to light.
Shoots are ___________ phototropic.
Positively
Roots are __________ phototropic.
Negatively
Define gravitropism.
The growth of a plant in response to gravity.
Shoots are _________ gravitropic.
Negatively - they grow upwards.
Roots are __________ gravitropic.
Positively - they grow downwards.
What is IAA?
An auxin produced in the tips of shoots in flowering plants.
How is IAA moved around the plant to control tropisms?
Over short distances, it moves by diffusion and active transport. Over long distances, via the phloem.
Why is there uneven growth in plants?
Due to the uneven distribution of IAA.
What happens at the shoots re phototropism?
At the shoots, IAA concentration increases on the shaded side - so the cells elongate and the shoot bends towards the light.
What happens at the roots re phototropism?
IAA concentration also increases on shaded side (like shoots) - so the growth is inibinit, so root bends away from the light.
What happens at the shoot re gravitropism?
IAA concentration increases in the lower side - so cells elongate, and the shoot grows upwards.
What happens at the root re gravitropism?
IAA concentration increases on the lower side - growth is inhibited so the root grows downwards.
