tropism

Question 1

What is tropism?

Answer 1

= term given when plants respond via growth to stimuli
= can be positive or negative
= plants respond to gravity, light and water
=

Question 2

What kind of factors is tropism controlled by?

Answer 2

= specific growth factors
= e.g: IAA

Question 3

where is IAA found?

Answer 3

= made in tip of roots and shoots, but can diffuse to other cells
= controls cell elongation

Question 4

What response is phototropism of shoots?

Answer 4

= positive
=photosynthesis, LDR
= controlled by IAA- plants grow towatds amd bend towatds light
= shoot tip cells,produces IAA,
= if light was equally distributed, the IAA would diffuse downwards away from the distrubution of light, cells elongate throughout the shoot so goes upwatds

= in oe direction of light, IAA diffuses from shoot tip to shaded part of the shoot- high concentreation on shaded side, cells elongate, extra weight causes it to bend towards the light

Question 5

What is the phototropism response of light in roots?

Answer 5

=roots do not photosythesise, and do not rewuire lught, and are more able to anchor the plantif they are deep into the soil further away from light
= a high concentration of IAA inhibits cell elongation, causing rot cels to elongate more on the lighter side so the roots bend away from the light
= negative phototropism
=

Question 6

What is gravitropism in shoots?

Answer 6

= IAA will diffuse from the upper side to the lower side of the shoot
= if a plant is verticle. this causes cells to elongate causing the plants to grow upwatds
= if a plant is on its side, this causes the shoot to go sidewards this is ngative

Question 7

What is gravitropism in roots?

Answer 7

= IAA moves to the lower sides of the roots so that the upper sides elongate, and the root bends towards gravity and anchors the plant in
= positive gravutrophism