Auxins

Question 1

Apical dominance

Answer 1

auxins produced from the main shoot inhibt the development of the lateral buds. the inhibition falls as the shoot grows further away and is removed if the apical shoot is lost.

Question 2

what do expansins do

Answer 2

Water Uptake: Water enters the cell, filling the vacuole.
Turgor Pressure: The vacuole expands, pressing the cytoplasm against the cell wall.
Cell Wall Resistance: The rigid cell wall prevents uncontrolled expansion.

How Auxin Helps Cell Expansion
pH Reduction: Auxin increases hydrogen ion (H⁺) concentration.
Cell Wall Loosening: Lower pH breaks bonds between cellulose and other polysaccharides.

Flexible Wall: The loosened cell wall allows expansion under turgor pressure.

Question 3

what is a lateral bud

Answer 3

shoot locates on the sides of the plant

Question 4

What do auxins do?

Answer 4

inhibit the growth of the lateral bud. As you move down there is less auxin so lateral bud growth may develop

Question 5

apical dominance

Answer 5

the stem of the plant is dominant over (i.e., grows more strongly than) other side stems;

Question 6

how do cytokines oppose the action of auxins

Answer 6

promote lateral bud growth

cytokinins are produced in the base of the shoot and move upward through the xylem.

They stimulate cell division in lateral buds, encouraging branching.

When auxin levels are high, cytokinin’s effect is blocked, keeping buds dormant.

If auxin levels drop (e.g., after pruning), cytokinins become more active, leading to lateral bud growth and a bushier plant.