Co- ordination

Question 1

What is the zone of elongation

Answer 1

The region below the stem tip where cells develop large vacuoles and expand

Question 2

What is the internode-

Answer 2

The distance between two nodes

Question 3

What is the apical bud

Answer 3

the growing tip of the stem, containing the apical meristem- where cell division occurs

Question 4

What is the node

Answer 4

The point from which a leaf grows from the stem

Question 5

What is auxin

Answer 5

-growing tip/ apex of stem
-stimulate elongation of cells- allow cells to easily stretch

Question 6

What is cytokinins

Answer 6

-Actively dividing tissue
-promote cell division- in combo with auxins

Question 7

What is gibberellins

Answer 7

-Apical/ terminal buds and leaves
-stimulate elongation of internodal regions- to increase overall length of the stem

Question 8

Describe the auxin action

Answer 8

-Auxins are produced in the cells of the apical meristem
they diffuse down to the zone of elongation
-they bind to specific receptors on cell surface membranes of new cells
-this causes the membrane pumps to move hydrogen ions out into cellulose cell walls
-This causes the pH to decrease- activates agents to loosen the linkages between cellulose microfibrils, allowing slippage between them, making the cell walls more flexible
-cells absorb water by osmosis, and flexible cell walls allow cells to expand, as extra water exerts increased hydrostatic pressure against
-the more auxin received in the zone of elongation, the more this effect allow cells to expand.