Plant growth factors

Question 1

What 3 stimuli do plants respond to?

Answer 1

Light
Gravity
Water

Question 2

What are plant growth factors essentially?

Answer 2

Hormones

Question 3

What plant growth factor controls cell elongation

Answer 3

IAA
(Indoleacetic acid)

Question 4

Process of phototropism in flowering plants

Answer 4

Cell in tip of shoot produces IAA
IAA transported evenly throughgout all regions as it moves down the shoot
Light causes IAA to move from light to shaded side of the shoot
Greater conc of IAA on shaded than light side
IAA causes cell elongation
Greater IAA conc on the shaded side means faster cell elongation than the light side, causing shoot tip to bend towards the light.

Question 5

What does IAA do in shoots

Answer 5

Cause cell elongation

Question 6

What does IAA do in roots

Answer 6

Inhibits cell elongation

Question 7

Gravitropism in flowering plants process (When the root is horizontal)

Answer 7

Cells in tip of root produce IAA
IAA transported to all sides of root
Gravity influences movement of IAA from upper to lower side of root
Greater IAA conc on lower side than upper
IAA inhibits cell elongation in roots
Lower side of root elongates slower than upper side, causing root to bend downwards

Question 8

Why is IAA only effective on young cell walls?

Answer 8

As cells mature, they become more rigid and stop responding to IAA