Control in plants. Flashcards
What is a tropism?
A growth in response to a stimulus.
What is an auxin and where is it produced?
It is a plant hormone and it is produced in the stem tips and roots.
What does auxin control?
It controls the direction of growth.
Where are plant hormones used?
Weed killers and rooting powder.
Name and explain the two main types of tropism.
Positive tropism: The plant grows towards the stimulus.
Negative tropism: The plant grows away from the stimulus.
What is phototropism?
A tropism where ‘light’ is the stimulus.
What is gravitropism?
A tropism where ‘gravity’ is the stimulus.
How do roots and shoots respond to a light stimulus?
Shoots: Grow towards the light.
Roots: Grow away from the light.
How do roots and shoots respond to a gravity stimulus?
Shoots: Grow away from gravity.
Roots: Grow in the direction of the force of gravity.
What do auxins change in plant cells?
The rate of ‘elongation’ which is ‘the action or process of lengthening something.
How do the cells in shoots and roots respond to high concentrations of auxins?
Shoots: They grow more.
Roots: They grow less.
Which side of a shoot contains more auxin and what does this mean?
The shaded side, it means the shaded side grows longer and the shoot bends towards the light.
How do selective weed killers kill weeds?
They contain growth hormones that make the weeds grow too quickly then they die.
