Question 1

Buds and sprouts often form on tree stumps. Which of the following hormones would you expect to stimulate their formation?

Accepted Answer

A) auxin 
B) cytokinins 
C) abscisic acid 
D) ethylene 
E) gibberellins 
A) auxin 
B) cytokinins 
C) abscisic acid 
D) ethylene 
E) gibberellins

Question 2

All of the following may function in signal transduction in plants except

Accepted Answer

A) calcium ions. 
B) nonrandom mutations. 
C) receptor proteins. 
D) phytochrome. 
E) second messengers. 
A) calcium ions. 
B) nonrandom mutations. 
C) receptor proteins. 
D) phytochrome. 
E) second messengers.

Question 3

We know from the experiments of the past that plants bend toward light because

Accepted Answer

A) they need sunlight energy for photosynthesis. 
B) the sun stimulates stem growth. 
C) cell expansion is greater on the dark side of the stem. 
D) auxin is inactive on the dark side of the stem. 
E) phytochrome stimulates florigen production. 
A) they need sunlight energy for photosynthesis. 
B) the sun stimulates stem growth. 
C) cell expansion is greater on the dark side of the stem. 
D) auxin is inactive on the dark side of the stem. 
E) phytochrome stimulates florigen production.

Question 4

The ripening of fruit and the dropping of leaves and fruit are principally controlled by

Accepted Answer

A) auxins 
B) cytokinins 
C) indole acetic acid 
D) ethylene 
E) carbon dioxide concentration (in air) 
A) auxins 
B) cytokinins 
C) indole acetic acid 
D) ethylene 
E) carbon dioxide concentration (in air)

Question 5

The hormone that helps plants respond to drought is

Accepted Answer

A) auxin. 
B) gibberellin. 
C) cytokinin. 
D) ethylene. 
E) abscisic acid. 
A) auxin. 
B) gibberellin. 
C) cytokinin. 
D) ethylene. 
E) abscisic acid.

Question 6

Auxin is responsible for all of the following plant growth responses except

Accepted Answer

A) phototropism. 
B) formation of adventitious roots. 
C) apical dominance. 
D) the detection of photoperiod. 
E) cell elongation. 
A) phototropism. 
B) formation of adventitious roots. 
C) apical dominance. 
D) the detection of photoperiod. 
E) cell elongation.

Question 7

What is the probable role of salicylic acid in the defense responses of plants?

Accepted Answer

A) destroy pathogens directly 
B) activate systemic acquired resistance of plants 
C) close stomata, thus preventing the entry of pathogens 
D) activate heat-shock proteins 
E) sacrifice infected tissues by hydrolyzing cells 
A) destroy pathogens directly 
B) activate systemic acquired resistance of plants 
C) close stomata, thus preventing the entry of pathogens 
D) activate heat-shock proteins 
E) sacrifice infected tissues by hydrolyzing cells

Question 8

In general, which of the following is not a plant response to herbivores?

Accepted Answer

A) domestication, so that humans can protect the plant 
B) attracting predatory animals, such as parasitoid wasps 
C) chemical defenses, such as toxic compounds 
D) physical defenses, such as thorns 
E) production of volatile molecules 
A) domestication, so that humans can protect the plant 
B) attracting predatory animals, such as parasitoid wasps 
C) chemical defenses, such as toxic compounds 
D) physical defenses, such as thorns 
E) production of volatile molecules

Question 9

Regarding positive gravitropism exhibited by plant roots,

Accepted Answer

A) it is mediated by auxin as for phototropism. 
B) it depends on more rapid elongation of some cells than other cells. 
C) gravity causes auxins to accumulate on the lower side of roots. 
D) the phenomenon depends upon inhibition of cell elongation of certain root cells by auxins. 
E) All of the above are correct. 
A) it is mediated by auxin as for phototropism. 
B) it depends on more rapid elongation of some cells than other cells. 
C) gravity causes auxins to accumulate on the lower side of roots. 
D) the phenomenon depends upon inhibition of cell elongation of certain root cells by auxins. 
E) All of the above are correct.

Question 10

The results of this experiment, shown on the left of the graph (area

Accepted Answer

A) , may be used to
A) show that these plants can live without gibberellin. 
B) show that gibberellin is necessary in positive gravitropism. 
C) show that taller plants with more gibberellin produce fruit (pods). 
D) show a correlation between plant height and gibberellin concentration. 
E) study phytoalexins in plants. 
A) , may be used to
A) show that these plants can live without gibberellin. 
B) show that gibberellin is necessary in positive gravitropism. 
C) show that taller plants with more gibberellin produce fruit (pods). 
D) show a correlation between plant height and gibberellin concentration. 
E) study phytoalexins in plants.

Question 11

In nature, poinsettias bloom in early March. Research has shown that the flowering process is triggered three months before blooming occurs. In order to make poinsettias bloom in December, florists change the length of the light-dark cycle in September. Given the information and clues above, which of the following is a False statement about poinsettias?

Accepted Answer

A) They are short-day plants. 
B) They require a light period shorter than some set maximum. 
C) They require a longer dark period than is available in September. 
D) The dark period can be interrupted without affecting flowering. 
E) They will flower even if there are brief periods of dark during the daytime. 
A) They are short-day plants. 
B) They require a light period shorter than some set maximum. 
C) They require a longer dark period than is available in September. 
D) The dark period can be interrupted without affecting flowering. 
E) They will flower even if there are brief periods of dark during the daytime.

Question 12

The houseplants in a windowless room with only fluorescent lights begin to grow tall and leggy. Which of the following treatments would promote more normal growth?

Accepted Answer

A) Leave the lights on at night as well as during the day. 
B) Add additional fluorescent tubes to increase the light output. 
C) Add some incandescent bulbs to increase the amount of red light. 
D) Set a timer to turn on the lights for 5 minutes during the night. 
E) Turn off the lights for 5 minutes during the day. 
A) Leave the lights on at night as well as during the day. 
B) Add additional fluorescent tubes to increase the light output. 
C) Add some incandescent bulbs to increase the amount of red light. 
D) Set a timer to turn on the lights for 5 minutes during the night. 
E) Turn off the lights for 5 minutes during the day.

Question 13

How may a plant respond to severe heat stress?

Accepted Answer

A) by orienting leaves toward the sun, increases evaporative cooling 
B) by producing ethylene, which kills some cortex cells and creates air tubes for ventilation 
C) by producing salicylic acid, which initiates a systemic acquired resistance response 
D) by increasing the proportion of unsaturated fatty acids in cell membranes reducing their fluidity 
E) by producing heat-shock proteins, which may protect the plant's proteins from denaturing 
A) by orienting leaves toward the sun, increases evaporative cooling 
B) by producing ethylene, which kills some cortex cells and creates air tubes for ventilation 
C) by producing salicylic acid, which initiates a systemic acquired resistance response 
D) by increasing the proportion of unsaturated fatty acids in cell membranes reducing their fluidity 
E) by producing heat-shock proteins, which may protect the plant's proteins from denaturing

Question 14

If a long-day plant has a critical night length of 9 hours, which 24-hour cycle would prevent flowering?

Accepted Answer

A) 16 hours light/8 hours dark 
B) 14 hours light/10 hours dark 
C) 15.5 hours light/8.5 hours dark 
D) 4 hours light/8 hours dark/4 hours light/8 hours dark 
E) 8 hours light/8 hours dark/light flash/8 hours dark 
A) 16 hours light/8 hours dark 
B) 14 hours light/10 hours dark 
C) 15.5 hours light/8.5 hours dark 
D) 4 hours light/8 hours dark/4 hours light/8 hours dark 
E) 8 hours light/8 hours dark/light flash/8 hours dark

Question 15

Plant cells begin synthesizing large quantities of heat-shock proteins

Accepted Answer

A) after the induction of chaperone proteins. 
B) in response to the lack of CO2 following the closing of stomata by ethylene. 
C) when desert plants are quickly removed from high temperatures. 
D) when they are subjected to moist heat (steam)followed by electric shock. 
E) when the air around species from temperate regions is above 40°C. 
A) after the induction of chaperone proteins. 
B) in response to the lack of CO2 following the closing of stomata by ethylene. 
C) when desert plants are quickly removed from high temperatures. 
D) when they are subjected to moist heat (steam)followed by electric shock. 
E) when the air around species from temperate regions is above 40°C.

Question 16

If a short-day plant has a critical night length of 15 hours, then which of the following 24-hour cycles will prevent flowering?

Accepted Answer

A) 8 hours light/16 hours dark 
B) 4 hours light/20 hours dark 
C) 6 hours light/2 hours dark/light flash/16 hours dark 
D) 8 hours light/8 hours dark/light flash/8 hours dark 
E) 2 hours light/20 hours dark/2 hours light 
A) 8 hours light/16 hours dark 
B) 4 hours light/20 hours dark 
C) 6 hours light/2 hours dark/light flash/16 hours dark 
D) 8 hours light/8 hours dark/light flash/8 hours dark 
E) 2 hours light/20 hours dark/2 hours light

Question 17

A short-day plant exposed to nights longer than the minimum for flowering but interrupted by short flashes of light will flower.

Accepted Answer

A) True 
 B)False

Question 18

Figure 39.1
-The heavy line in Figure 39.1 illustrates the relationship between auxin concentration and cell growth in stem tissues. If the same range of concentrations were applied to lateral buds, what curve would probably be produced?

Accepted Answer

A) I 
B) II 
C) III 
D) II and III 
E) either I or III 
A) I 
B) II 
C) III 
D) II and III 
E) either I or III

Question 19

After some time, the tip of a plant that has been forced into a horizontal position grows upward. This phenomenon is related to

Accepted Answer

A) light. 
B) whether the plant is in the northern or southern hemisphere. 
C) gibberellin production by stems. 
D) auxin production in roots. 
E) auxin movement toward the lower side of the stem. 
A) light. 
B) whether the plant is in the northern or southern hemisphere. 
C) gibberellin production by stems. 
D) auxin production in roots. 
E) auxin movement toward the lower side of the stem.

Question 20

Why might animal hormones function differently from plant hormones?

Accepted Answer

A) Animals move rapidly away from negative stimuli, and most plants don't. 
B) Plant cells have a cell wall that blocks passage of many hormones. 
C) Plants must have more precise timing of their reproductive activities. 
D) Plants are much more variable in their morphology and development than animals. 
E) Both A and D are correct. 
A) Animals move rapidly away from negative stimuli, and most plants don't. 
B) Plant cells have a cell wall that blocks passage of many hormones. 
C) Plants must have more precise timing of their reproductive activities. 
D) Plants are much more variable in their morphology and development than animals. 
E) Both A and D are correct.

Exam 39: Plant Responses to Internal and External Signals

Buds and sprouts often form on tree stumps. Which of the following hormones would you expect to stimulate their formation?

All of the following may function in signal transduction in plants except

We know from the experiments of the past that plants bend toward light because

The ripening of fruit and the dropping of leaves and fruit are principally controlled by

The hormone that helps plants respond to drought is

Auxin is responsible for all of the following plant growth responses except

What is the probable role of salicylic acid in the defense responses of plants?

In general, which of the following is not a plant response to herbivores?

Regarding positive gravitropism exhibited by plant roots,

The results of this experiment, shown on the left of the graph (area

The houseplants in a windowless room with only fluorescent lights begin to grow tall and leggy. Which of the following treatments would promote more normal growth?

How may a plant respond to severe heat stress?

If a long-day plant has a critical night length of 9 hours, which 24-hour cycle would prevent flowering?

Plant cells begin synthesizing large quantities of heat-shock proteins

If a short-day plant has a critical night length of 15 hours, then which of the following 24-hour cycles will prevent flowering?

A short-day plant exposed to nights longer than the minimum for flowering but interrupted by short flashes of light will flower.

Figure 39.1 -The heavy line in Figure 39.1 illustrates the relationship between auxin concentration and cell growth in stem tissues. If the same range of concentrations were applied to lateral buds, what curve would probably be produced?

After some time, the tip of a plant that has been forced into a horizontal position grows upward. This phenomenon is related to

Why might animal hormones function differently from plant hormones?

Introduction: Themes in the Study of Life

The Chemical Context of Life

Water and the Fitness of the Environment

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Cellular Respiration: Harvesting Chemical Energy

Photosynthesis

Cell Communication

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

From Gene to Protein

Control of Gene Expression

Viruses

Biotechnology

Genomes and Their Evolution

Descent With Modification: a Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity Ii: the Evolution of Seed Plants

Fungi

An Introduction to Animal Diversity

Invertebrates

Vertebrates

Plant Structure, Growth, and Development

Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signaling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behavior

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems

Conservation Biology and Restoration Ecology

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