IB Biology C3.1 (AHL): plant hormones & tropic responses

Question 1

Gibberellins influence many aspects of plant growth among them are?

Accepted Answer

stem elongation, seed germination

Question 2

What are the two forms of auxin and in which part of the cell do they occur?

Accepted Answer

auxin with a negative charge - in the cytoplasm, auxin with no charge - in the cell wall

Question 3

Which plant hormone is most responsible for phototropism?

Accepted Answer

auxin

Question 4

Negatively charged auxin needs to be transported by auxin pumps, uncharged auxin diffuses through the cell wall

Accepted Answer

True

Question 5

Which hormone signals stomata to close during water shortages?

Accepted Answer

absicis acid (ABA)

Question 6

What happens to auxin-responsive genes when auxin binds its receptor inside cells?

Accepted Answer

genes are activated

Question 7

Ethylene gas is commonly associated with what process?

Accepted Answer

fruit ripening

Question 8

What happens to auxin after diffusing into a cell and why?

Accepted Answer

the cytoplasm is slightly basic, It is deprotonated and negatively charged because...

Question 9

What is the role of cytokinins in plants?

Accepted Answer

promote cell division, and shut down cell expansion

Question 10

What do the two forms of auxin mean for auxin transport?

Accepted Answer

charged auxin is actively transported out of cells, uncharged auxin passively diffuses into cells

Question 11

Why is auxin charged in the cytoplasm and uncharged in the cell wall?

Accepted Answer

the cell wall is slightly acidic, the cytoplasm is slightly basic

Question 12

In phototropism, auxins accumulate on which side of the stem?

Accepted Answer

the shaded side

Question 13

Which hormone balance encourages shoot growth?

Accepted Answer

high cytokinins, low auxins

Questions 13