tropic responses

Question 1

what is tropism

Answer 1

growth movement in plants related to directional stimuli

Question 2

what is phototropism

Answer 2

growth response towards or away from the direction from which light is coming

Question 3

what is gravitropism

Answer 3

growth response towards or away from gravity

Question 4

what is positive and negative response

Answer 4

-if plan organ grows towards stimulus — positive response
- if plant organ grows away from stimulus– negative response

Question 5

positive phototropism/ negative gravitropism of shoots

Answer 5

• leaves are in optimum position to absorb light for photosynthesis
• flowers are exposed abd more likely to receive pollen

Question 6

positive gravitropism of roots

Answer 6

root grows into soil which is: - source of water and minerals
- means of anchorage

Question 7

what is auxin

Answer 7

• plant growth is controlled by growth substances such as auxin
• auxin is produced in the tips of roots and shoots ad diffuses to the region of extension

Question 8

positive phototropism of shoot with auxin

Answer 8

• auxin produced in tip
• auxin moves to the shaded side. There it stimulates cell elongation
• cells on shaded side grow more than those on the lit side, causing the stem to grow towards the light

Question 9

negative gravitropism of shoot

Answer 9

• shoot places horizontally in the absence of light ( to exclude positive phototropism)
• auxin accumulates on the lower side due to gravity
• there it stimulates cell elongation, so shoot grows upwards

Question 10

positive gravitropism of root with auxin

Answer 10

• root placed horizontally
• auxin produced in tip
• more auxin accumulates on the lower side
• there it inhibits cell elongation, so the root curves downwards