nervous communication-plant responses Flashcards
(12 cards)
what are directional growth responses called
tropisms
what is phototropism
growth in response to direction of light
what are shoots and roots in terms of phototropism
-shoots are positively phototropic (they grow towards light)
-roots are negatively phototropic (they grow away from light)
what is gravitropism
growth in response to direction of gravity
what are shoots and roots in terms of gravitropism
-shoots are negatively gravitropic (they grow upwards away from the gravitational pull)
-roots are positively gravitropic (they grow downwards towards the gravitational pull)
what is IAA
a type of auxin that controls the tropic response in plants
how is IAA transported
-over short distances through diffusion and active transport
-over long distances in the phloem
how does IAA work
-when directional stimuli is detected IAA is transported to different parts of plants
-uneven distribution of IAA
-when distribution is uneven creates a directional growth response
how does IAA work in phototropism of shoots
-IAA is transported to the more shaded part
-higher concentration of IAA in the shaded part causes cells in shaded area to elongate
-causes shoot to bend towards light
how does IAA work in phototropism of roots
-IAA is transported to more shaded part
-higher concentration of IAA in the shaded part inhibits cell elongation which causes the root to bend away from light
how does IAA work in gravitropism of shoots
-IAA is transported to the underside
-causes underside to elongate
-causes shoot to bend away from gravitational pull
how does IAA work in gravitropism of roots
-IAA is transported to underside
-underside inhibits cell elongation on the lower side so the roots bend towards the gravitational pull
