Lecture 9

Question 1

Plant hormonal regulation differs from animal hormonal regulation in that _____.

a. there are no dedicated hormone-producing organs in plants as there are in animals
b. all production of hormones is local in plants with little long-distance transport
c. only animal hormones may have either external or internal receptors
d. only animal hormone concentrations are developmentally regulated

Answer 1

a. there are no dedicated hormone-producing organs in plants as there are in animals

Question 2

Plant hormones produce their effects by _____.
I) altering the expression of genes
II) modifying the permeability of the plasma membrane
III) modifying the structure of the nuclear envelope membrane

a. only I
b. only II
c. only III
d. only I and II

Answer 2

d. only I and II

Question 3

Which of the following statements best summarizes the acid-growth hypothesis in an actively growing shoot?

a. Auxin stimulates proton pumps in the plasma membrane and tonoplast.
b. Auxins and gibberellins together act as a lubricant to help stretch cellulose microfibrils.
c. Auxins activate aquaporins that increase turgor pressure in the cells.
d. Auxin-activated proton pumps lower the pH of the cell wall, which breaks bonds and makes the walls more flexible.

Answer 3

d. Auxin-activated proton pumps lower the pH of the cell wall, which breaks bonds and makes the walls more flexible.