2.6 - Hormones and the control of plant growth Flashcards
1
Q
What three things are plants sensitive to?
A
- Light
- Gravity
- Moisture
2
Q
What do plant shoots grow towards? What is this response called?
A
They grow towards light; this response is phototropism
3
Q
What two things do plant roots grow towards? What is one of these responses called?
A
- Towards gravity; this response it called gravitropism, or geotropism
- Towards moisture
4
Q
What is auxin?
A
The hormone which control phototropism and gravitropism in plants
5
Q
Why do shoots bend towards light? (3)
A
- Light is a stimuli
- This causes an unequal distribution of auxin, which causes unequal growth in the shoot
- This results in the bending of the shoot
6
Q
Why do roots bend towards gravity? (4)
A
- Gravity causes more auxin to gather on the lower side of the root
- This causes an unequal distribution of auxin
- The root grows more on the side with the least auxin, making it bend and grow down towards the force of gravity
- When it has grown down, the auxin becomes evenly spread again
7
Q
Why do shoots bend away from gravity? (4)
A
- Gravity causes more auxin to gather on the lower side of the shoot
- This causes an unequal distribution of auxin
- The root grows more on the side with the more auxin, making it bend and grow up away the force of gravity
- When it has grown up, the auxin becomes evenly spread again
8
Q
What does unequal distribution of auxin cause?
A
Unequal growth, which causes the shoot or root to bend
9
Q
What two ways can plant growth hormones be used?
A
- As weed killers
- To stimulate root growth
