topic 6 responses in plants and animals

Question 1

what is a tropism?

Answer 1

response of a plant to a directional stimulus

Question 2

how do plants respond to stimuli?

Answer 2

by regulating their growth

Question 3

what is a positive tropism?

Answer 3

growth towards the stimulus

Question 4

what is a negative tropism?

Answer 4

growth away from the stimulus

Question 5

what is phototropism?

Answer 5

the growth of a plant in response to light

Question 6

how do shoots respond to light?

Answer 6

positively phototropic- grow towards light

Question 7

how do roots respond to light?

Answer 7

negatively phototropic- grow away from light

Question 8

what is gravitropism?

Answer 8

growth of a plant in response to gravity

Question 9

how do shoots respond to gravity?

Answer 9

negatively gravitropic- grow upwards

Question 10

how do roots respond to gravity?

Answer 10

positively gravitropic- grow downwards

Question 11

what is a growth factor?

Answer 11

hormone like chemical that speeds up/slows down plant growth

Question 12

where are growth factors produced?

Answer 12

in the growing regions of the plant, move to where they are needed in other parts of the plant

Question 13

what is auxin?

Answer 13

growth factor that stimulates the growth of shoots by cell elongation

Question 14

what happens if the concentration of auxin is high?

Answer 14

can inhibit growth in roots

Question 15

what is indoleacetic acid? (IAA)

Answer 15

auxin that is produced in the tips of shoots in flowering plants

Question 16

how is indoleacetic acid moved around the plant?

Answer 16

by diffusion and active transport over short distances

via the phloem over long distances

Question 17

what does uneven distribution of indoleacetic acid mean?

Answer 17

that there is uneven growth in the plant

Question 18

what happens in phototropism? (IAA)

Answer 18

IAA moves to the shaded parts of shoots and roots, so there is uneven growth

Question 19

what happens to IAA in the shoot during phototropism?

Answer 19

IAA concentration increases on the shaded side, cells elongate and the shoot bends towards the light

Question 20

what happens to the IAA in the root during phototropism?

Answer 20

IAA concentration increases on the shaded side- growth is inhibited so the root bends away from the light

Question 21

what happens to IAA during geotropism?

Answer 21

IAA moves to the underside of shoots and roots, so there is uneven growth

Question 22

what happens to IAA concentration in the shoot during gravitropism?

Answer 22

IAA concentration increases on the lower side- cells elongate so the shoot grows upwards

Question 23

what happens to the IAA concentration in the root during gravitropism?

Answer 23

IAA concentration increases on the lower side- growth is inhibited so the root grows downwards

Question 24

what is a tactic response?

Answer 24

organisms move towards or away from a directional stimulus eg) light

Question 25

what is a kinetic response?

Answer 25

organisms movement is affected by a non directional stimulus, eg humidity

Question 26

what is a positive taxis?

Answer 26

when an organism moves towards a stimulus

Question 27

what is a negative taxis?

Answer 27

when an organism moves away from a stimulus