B11.9 - Plant Hormones And Responses

Question 1

What is auxin?

Answer 1

Auxin is a plant hormone that controls growth neat the tips of shoots and roots

Question 2

What does auxin respond to?

Answer 2

Light and gravity

Question 3

How does auxin make shoots grow towards light?

Answer 3

1) When a shot tip,is exposed to light more auxin accumulates on the side that is in the shade
2) It stimulates cells to elongate faster on the shaded side so the shoot bends towards the ligth

Question 4

Why may the shoot stop growing if the tip is removed?

Answer 4

No auxin is available

Question 5

How does a shoot curve away from gravity?

Answer 5

1) When a shoot is growing sideways gravity produces an unequal distribution of auxin in the tip (more auxin in lower side)
2) This causes the lower side to grow faster, bending the shoot upwards

Question 6

How do roots curve towards gravity?

Answer 6

1) A root growing sideways will have more auxin on the lower side due to gravity
2) In roots, extra auxin inhibits growth and so the root bends downwards