Test 3 Review: Phytohormones

Question 1

What best describes the nature of majority of phytohormones?

Answer 1

Small organic molecules

Question 2

Pleiotropic

Answer 2

one hormone has many different effects

Question 3

What characteristics are shared by hormones in plants and animals?

Answer 3

Active in small quantities
Action involves a receptor
Act at a distance from place of production

Question 4

What was the first phytohormone to be discovered?

Answer 4

Auxin

Question 5

Darwin proposed that unidirectional light resulted in the movement of “some substance” from the tip to the elongation region of the coleoptile. What is the substance?

Answer 5

Auxin

Question 6

What six things must you identify to fully describe the action of a phytohormone?

Answer 6

Triggering phenomena/signal
Synthesis
Transport
Receptor
Signal transduction
Downstream effects

Question 7

What is the first downstream event from the binding of auxin or gibberellin to the respective receptors?

Answer 7

Protein destruction

Question 8

In effect, we can describe the mode of action of auxin and gibberellin how?

Answer 8

Inhibition of inhibitor

Question 9

A fungus disease of rice called “foolish seedling disease” resulted in the discovery of which phytohormone?

Answer 9

Gibberellin

Question 10

The development of which plant hormone pathway was essential for the ability of land plants to survive the desiccating terrestrial environment?

Answer 10

Abscisic acid

Question 11

If you wanted to delay fruit ripening, which hormone pathway would you need to inhibit?

Answer 11

Ethylene

Question 12

Adjusting the ratios of what two hormones results in callus maintenance or the differentiation of either roots or shoots from callus?

Answer 12

Auxin and cytokinin