Biology

Eldra P. Solomon, Charles E. Martin, Diana W. Martin,

Chapter 38

Plant Developmental Responses to External and Internal Signals - all with Video Answers

Educators

Chapter Questions

Problem 1

In the signal transduction process for the hormone auxin, the molecule ubiquitin (a) absorbs blue light (b) becomes phosphorylated (c) tags certain proteins for destruction (d) interacts antagonistically with gibberellins (e) binds to a receptor in the plant cell's plasma membrane.

Danielle Ashley

Danielle Ashley

Numerade Educator

Problem 2

When you prune shrubs to make them "bushier" - that is, to prevent apical dominance -you are affecting the distribution and action of which plant hormone? (a) auxin (b) jasmonic acid (c) salicylic acid (d) ethylene (e) abscisic acid.

KP

Karenza Pearson

Numerade Educator

Problem 3

Research on a fungal disease of rice provided the first clues about the plant hormone (a) auxin (b) gibberellin (c) cytokinin (d) ethylene (e) abscisic acid.

Danielle Ashley

Danielle Ashley

Numerade Educator

Problem 4

This plant hormone interacts with auxin during the formation of plant organs in tissue culture. (a) florigen
(b) gibberellin $(c)$ cytokinin $(d)$ ethylene (e) abscisic acid.

KP

Karenza Pearson

Numerade Educator

Problem 5

The stress hormone that helps plants respond to drought is (a) auxin (b) gibberellin (c) cytokinin (d) ethylene (e) abscisic acid.

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Karenza Pearson

Numerade Educator

Problem 6

This hormone promotes seed dormancy. (a) auxin (b) gibberellin (c) cytokinin (d) ethylene (e) abscisic acid.

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Karenza Pearson

Numerade Educator

Problem 7

The three classes of photoreceptors that enable plants to sense the presence and duration of light are (a) phytochrome, cryptochrome, and circadian rhythms (b) chlorophyll, photosynthesis, and photoperiodism (c) phytochrome, photoperiodism, and chlorophyll (d) phytochrome, cryptochrome, and phototropin (e) phototropin, photosynthesis, and photoperiodism.

KP

Karenza Pearson

Numerade Educator

Problem 8

Pfr, the active state of _______________, forms when red light is absorbed. (a) photosystem I (b) phytochrome (c) far-red light (d) phototropin (e) cryptochrome.

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Karenza Pearson

Numerade Educator

Problem 9

Which photoreceptor(s) is/are implicated in resetting the biological clock? (a) phytochrome only (b) cryptochrome only (c) phototropin only (d) cryptochrome and gibberellin (e) phytochrome and cryptochrome.

Danielle Ashley

Danielle Ashley

Numerade Educator

Problem 10

Which signaling molecule triggers the release of volatile substances that attract parasitic wasps to plant-eating caterpillars? (a) phytochrome (b) jasmonic acid (c) auxin (d) methyl salicylate (e) gibberellin.

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Karenza Pearson

Numerade Educator

Problem 11

Arrange the following steps in the correct order in the phytochrome signal transduction pathway: 1 . red light; 2. light-responsive gene is switched on (or off); $3 .$ movement of Pfr to nucleus; $4 .$ conversion of Pr to Pfr; $5 .$ formation of Pfr-PIF3 complex that is bound to promoter region.

Danielle Ashley

Danielle Ashley

Numerade Educator

Problem 12

State whether flowering in a short-day plant with a minimum critical night length of 14 hours would be expected to occur in the following situations. Explain each answer.
(a) The plant is exposed to 15 hours of daylight and 9 hours of uninterrupted darkness.
(b) The plant is exposed to 9 hours of daylight and 15 hours of darkness.
(c) The plant is exposed to 9 hours of daylight and 15 hours of darkness, with a 10 -minute exposure to red light in the middle of the night.

Danielle Ashley

Danielle Ashley

Numerade Educator

Problem 13

If you transplanted the short-day plant discussed in Question 12 to the Equator, would it flower? Explain your answer.

Danielle Ashley

Danielle Ashley

Numerade Educator

Problem 14

What adaptive advantages are conferred on a plant whose stems are positively phototropic and whose roots are positively gravitropic?

Danielle Ashley

Danielle Ashley

Numerade Educator

Problem 15

Explain why a plant with a mutation in one of its phytochrome genes that affects flowering time would be at an evolutionary disadvantage.

Danielle Ashley

Danielle Ashley

Numerade Educator

Problem 16

Examine the figure. When the day length is 10 hours and the night length is 14 hours, what percentage of the plants flower? When the day length is 16 hours and the night length is 8 hours, what percentage of the plants flower? What is the critical night length for this plant?

Josee Pacheco

Numerade Educator

Problem 17

Do you think that our expanding knowledge of the molecular basis of plant signaling molecules could improve agricultural productivity in the future? Explain your answer.

Josee Pacheco

Numerade Educator