Responses in plants Flashcards
What is a tropism?
Response of a plant to a directional stimulus
How do plants respond to stimuli?
Regulate their growth
What is a positive tropism?
Growth towards the stimulus
What is a negative tropism?
A growth away from the stimulus
What is a phototropism?
The growth of a plant in response to light
What do shoots do in response to light?
Grow towards the light
Positively phototropic
What do roots do in response to light?
Grow away from the light
Negatively phototropic
What is a gravitropism?
The growth of a plant in response to gravity
What do shoots do in response to gravity?
Grow upwards
Negatively gravitropic
What do roots do in response to gravity?
Grow downwards
Positively gravitropic
What are growth factors?
Hormone-like chemicals that speed up or slow down plant growth
Where are plant growth factors produced?
In the growing regions of the plant, shoots and roots
Where do growth factors go?
They move from the growth regions to the other parts of the plant where they’re needed
What are auxins?
A type of growth factor
Where are auxins produced?
In the tips of shoots
How do auxins work?
They diffuse backwards to stimulate the cells behind the tips to elongate
Why does auxin go to cells behind the tips?
The cells become loose and stretchy
What happens to the growth of the plant if the top is removed?
No auxin will be available and the shoot stops growing
Where do auxins stimulate growth?
In shoots
What does high concentrations of auxin do?
Inhibit growth in the shoots
What is IAA?
Indoleacetic acid
Type of auxin
Produced in the tips of roots and shoots in flowering plants
How does IAA move?
By diffusion and active transport
Where does IAA move to in phototropism?
The shaded parts of roots and shoots, causing an uneven growth
Where does IAA move to in gravitropism?
The underside of roots and shoots so theres an uneven growth
