nervous communication-plant responses Flashcards
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
