14.2- Plant growth factors

?
  • Created by: Megan2413
  • Created on: 05-11-17 21:12
Why are plant hormones better described as plant growth factors?
They affect growth in all the plant and tend to affect the tissues they're released from unlike animals which send hormones to a target organ which is not necessarily the one by which the hormone was produced
1 of 14
Give an example of a common plant growth factor
Indoleacetic acid (IAA)
2 of 14
What group of subtsances does IAA belong to?
Auxins
3 of 14
Describe how positive phototropism occurs in the shoot of a plant using IAA
- Cells in the tip of the shoot produce IAA - It is transported down the shoot evenly - Light causes IAA to move to the shaded side of the shoot - IAA causes cell elongation on the shaded side of the shoot due to their being a higher IAA -->
4 of 14
concentration on the shaded side - The shaded side cells elongate at a faster rate than the light exposed side causing the shoot to grow towards the light
-->
5 of 14
How does IAA work in roots?
In roots IAA inhibits cell elongation causing a negative phototropic response
6 of 14
Describe how positive geotropism occurs in the root of a plant using IAA
- Cells in the tip of the root produce IAA which is transported along the root evenly - Gravity causes IAA from the upper side to move to the lower side of the root - IAA inhibits root cell elongation on the lower side causing the root to grown -->
7 of 14
downwards towards the force of gravity
-->
8 of 14
How are shoots negatively geotropic?
The greater IAA concentration on the lower side increases cell elongation and causes this side to elongate more than the upper side which causes the shoot to grow upwards against gravity
9 of 14
The distribution of what is affected by gravity in many plants?
IAA carrier proteins which export IAA from cells
10 of 14
What is the other effect that IAA can have on plants allowing their cells to elongate?
It increases plasticity
11 of 14
By which hypothesis does IAA increase plasticity?
Acid growth hypothesis
12 of 14
What is the acid growth hypothesis?
It involves the active transport of H+ ions from the cytoplasm into the spaces in cells walls causing it to become more plastic, allowing the cell to elongate
13 of 14
Why do older or more mature plant cells not respond to the acid growth hypothesis as well?
They develop greater rigidity as they mature in their cell walls
14 of 14

Other cards in this set

Card 2

Front

Give an example of a common plant growth factor

Back

Indoleacetic acid (IAA)

Card 3

Front

What group of subtsances does IAA belong to?

Back

Preview of the front of card 3

Card 4

Front

Describe how positive phototropism occurs in the shoot of a plant using IAA

Back

Preview of the front of card 4

Card 5

Front

concentration on the shaded side - The shaded side cells elongate at a faster rate than the light exposed side causing the shoot to grow towards the light

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Survival and response resources »