Plant Hormones And Growth Flashcards
What do plants need to coordinate and control growth?
Hormones
Hormones are essential for processes like tropisms.
What is phototropism?
The response to light
Phototropism involves plants growing towards a light source.
What is gravitropism (or geotropism)?
The response to gravity
Gravitropism refers to how plants respond to gravitational pull.
How do hormones move in plants?
From the place they are made to where they are needed
This movement allows for appropriate responses to stimuli.
What is the role of auxin in phototropism?
Stimulates cells to grow more on the shaded side
This causes the shoot to bend towards the light.
What happens when a plant shoot is exposed to light on one side?
Auxin moves to the shaded side, causing the shoot to bend towards the light
This enhances light absorption for photosynthesis.
What is negative gravitropism?
Growth away from gravity
Most shoots exhibit negative gravitropism.
What happens to auxin distribution when a shoot is horizontal?
Auxin moves to the lower side
This causes the shoot to bend upwards away from the ground.
Why is negative gravitropism beneficial for shoots?
Higher light levels are likely further away from the ground
This increases the rate of photosynthesis.
What is positive gravitropism?
Growth towards gravity
Most roots show positive gravitropism.
What happens when a root is horizontal?
Auxin moves to the lower side, stimulating growth on the upper side
This causes the root to bend downward.
Why is positive gravitropism beneficial for roots?
Increased levels of water and nutrients lower down
It also provides stability for the plant.
What occurs when auxin distribution becomes equal on both sides?
The plant grows straight in that direction
Equal auxin distribution results in straight growth.
How can you investigate the effect of light on seedlings?
Place them in a cardboard box and shine light from one side
This setup demonstrates phototropism.
How can you investigate the effect of gravity on seedlings?
Attach a petri dish containing the seedlings to a wall
This allows observation of gravitropism.
