Lecture 17: Plant Hormones + Plant Growth Regulators - 11/8

Question 1

What is a hormone?

Answer 1

An organic molecule that is made in a specific cell/tissue and is transported to other cells/tissues where it has a specific effect at very low concentrations

Question 2

Are molecules called ‘plant growth regulators’ typically synthetic or organic molecules?

Answer 2

Synthetic molecules

Question 3

What are the 5 traditional plant hormones?

Answer 3

Auxin, abscisic acid, gibberellins, cytokinin, and ethylene

Question 4

Which parts of metabolism provide the building blocks for plant hormones?

Answer 4

Glycolysis, the Krebs cycle, and the PPP (pentose phosphate pathway)

Question 5

Do PGR molecules participate directly in metabolism?

Answer 5

No

Question 6

How does the perception of a signal occur in plants?

Answer 6

Proteins called receptors recognize a molecule or specific stimulus, resulting in a change in protein configuration

Question 7

What is context-dependent activity?

Answer 7

When a plant’s response depends on context

e.g. ethylene usually promotes flower bud loss, but instead promotes flowering in bromeliads

Question 8

What are the major functions and uses of abscisic acid?

Answer 8

Major functions: stomata closure
Major uses: few

Question 9

What are the major functions and uses of auxin?

Answer 9

Major functions: cell enlargement/division, stimulates root initiation, encourages apical dominance
Major uses: herbicide, rooting cuttings, increased fruit set, preventing pre-harvest fruit drop

Question 10

What are the major functions and uses of cytokinin?

Answer 10

Major functions: promotes cell division, inhibits senescence (deterioration)
Major uses: promote flowering and inhibit senescence

Question 11

What are the major functions and uses of gibberellin?

Answer 11

Major functions: promotes cell elongation and division, seed germination, induces flowering and starch breakdown
Major uses: produce seedless & larger grapes, increased malt production

Question 12

What are the major functions and uses of ethylene?

Answer 12

Major functions: induces ripening in climacteric fruits, promotes abscission, mediates stress responses, stimulates adventitious root development
Major uses: fruit ripening/abscission, promotion of female flower production in cucurbits