lecture 20

Question 1

what are plant hormones?

Answer 1

chemicals produced by the plant which act as signals that alter growth and/or development

Question 2

what determines whether a hormone will affect a certain cell or tissue?

Answer 2

the sensitivity of the target

Question 3

what are the functions of auxin?

Answer 3

promote stem elongation, root growth, phototropism, and gravitropism

Question 4

what are the functions of cytokinins?

Answer 4

growth regulators; important for cell division

Question 5

what are the functions of gibberellins?

Answer 5

regulators of stem elongation

Question 6

what are the functions of ABA (abscisic acid)?

Answer 6

seed development, maturation, dormancy, and plant stress

Question 7

what are the functions of ethylene?

Answer 7

fruit ripening and senescence

Question 8

how do we know about hormone function?

Answer 8

hormone function was identified in the late 19th, early 20th century by observing the role of the coleoptile tip on blue-light induced phototropism

Question 9

how does auxin induce cell expansion?

Answer 9

auxin weakens the cell wall by acidifying the apoplast and inducing proteins called expansins, which loosen the hydrogen bonds between cell wall polysaccharides