Question 1

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)  4 hours light/8 hours dark/4 hours light/8 hours dark 
D)  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)  4 hours light/8 hours dark/4 hours light/8 hours dark 
D)  8 hours light/8 hours dark/light flash/8 hours dark

Question 2

Figure 31.1
The heavy line in Figure 31.1 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(s) would probably be produced?

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  II or III 
A)  I 
B)  II 
C)  III 
D)  II or III

Question 3

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

Accepted Answer

A)  auxins. 
B)  cytokinins. 
C)  indoleacetic acid (IA
A) . 
D)  ethylene. 
A)  auxins. 
B)  cytokinins. 
C)  indoleacetic acid (IA
A) . 
D)  ethylene.

Question 4

Which of the following treatments would enhance the level of the Pfr form of phytochrome?

Accepted Answer

A)  exposure to far-red light 
B)  exposure to red light 
C)  long dark period 
D)  inhibition of protein synthesis 
A)  exposure to far-red light 
B)  exposure to red light 
C)  long dark period 
D)  inhibition of protein synthesis

Question 5

Plant hormones can have different effects at different concentrations. This explains how

Accepted Answer

A)  some plants are long-day plants and others are short-day plants. 
B)  signal transduction pathways in plants are different from those in animals. 
C)  plant genes recognize pathogen genes. 
D)  auxin can stimulate cell elongation in apical meristems, yet will inhibit the growth of axillary buds. 
A)  some plants are long-day plants and others are short-day plants. 
B)  signal transduction pathways in plants are different from those in animals. 
C)  plant genes recognize pathogen genes. 
D)  auxin can stimulate cell elongation in apical meristems, yet will inhibit the growth of axillary buds.

Question 6

Which of the following statements best summarizes the acid growth hypothesis in an actively growing shoot?

Accepted Answer

A)  Auxin stimulates proton pumps in the plasma membrane and tonoplast. 
B)  Auxin-activated proton pumps lower the pH of the cell wall, which breaks bonds and makes the walls more flexible. 
C)  Auxins and gibberellins together act as a lubricant to help stretch cellulose microfibrils. 
D)  Auxins activate aquaporins that increase turgor pressure in the cells. 
A)  Auxin stimulates proton pumps in the plasma membrane and tonoplast. 
B)  Auxin-activated proton pumps lower the pH of the cell wall, which breaks bonds and makes the walls more flexible. 
C)  Auxins and gibberellins together act as a lubricant to help stretch cellulose microfibrils. 
D)  Auxins activate aquaporins that increase turgor pressure in the cells.

Question 7

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

Accepted Answer

A)  to destroy pathogens directly 
B)  to activate the systemic acquired resistance of plants 
C)  to close stomata, thus preventing the entry of pathogens 
D)  to activate heat-shock proteins 
A)  to destroy pathogens directly 
B)  to activate the systemic acquired resistance of plants 
C)  to close stomata, thus preventing the entry of pathogens 
D)  to activate heat-shock proteins

Question 8

When an arborist prunes a limb off a valuable tree, he or she usually paints the cut surface. The primary purpose of the paint is to

Accepted Answer

A)  minimize water loss by evaporation from the cut surface. 
B)  improve the appearance of the cut surface. 
C)  stimulate growth of the cork cambium to "heal" the wound. 
D)  block entry of pathogens through the wound. 
A)  minimize water loss by evaporation from the cut surface. 
B)  improve the appearance of the cut surface. 
C)  stimulate growth of the cork cambium to "heal" the wound. 
D)  block entry of pathogens through the wound.

Question 9

Figure 31.2
-This experiment suggests that the unknown amount of gibberellin in the experimental plant (B) is approximately

Accepted Answer

A)  zero. 
B)  0.01 μg/mL. 
C)  0.1 μg/mL. 
D)  1.0 μg/mL. 
A)  zero. 
B)  0.01 μg/mL. 
C)  0.1 μg/mL. 
D)  1.0 μg/mL.

Question 10

________ promote(s) stomatal closure in plant leaves during drought stress.

Accepted Answer

A)  Auxins 
B)  Cytokinins 
C)  Gibberellins 
D)  Abscisic acid 
A)  Auxins 
B)  Cytokinins 
C)  Gibberellins 
D)  Abscisic acid

Question 11

What do the results of research on gravitropic responses of roots and stems show?

Accepted Answer

A)  Different tissues have the same response to auxin. 
B)  The effect of a plant hormone can depend on the tissue. 
C)  Some responses of plants require no hormones at all. 
D)  Light is required for the gravitropic response. 
A)  Different tissues have the same response to auxin. 
B)  The effect of a plant hormone can depend on the tissue. 
C)  Some responses of plants require no hormones at all. 
D)  Light is required for the gravitropic response.

Question 12

In an experiment, a plant physiologist has four groups of bananas of the same species. He exposes each of the four groups of bananas with the same concentration of auxins, gibberellins, abscisic acid, or ethylene. Which of these four groups of bananas ripen the fastest?

Accepted Answer

A)  auxins 
B)  gibberellins 
C)  abscisic acid 
D)  ethylene 
A)  auxins 
B)  gibberellins 
C)  abscisic acid 
D)  ethylene

Question 13

A botanist discovers a plant that lacks the ability to form starch grains in root cells, yet the roots still grow downward. This evidence refutes the long-standing hypothesis that

Accepted Answer

A)  falling statoliths trigger gravitropism. 
B)  starch accumulation triggers the negative phototropic response of roots. 
C)  starch grains block the acid growth response in roots. 
D)  starch is converted to auxin, which causes the downward bending in roots. 
A)  falling statoliths trigger gravitropism. 
B)  starch accumulation triggers the negative phototropic response of roots. 
C)  starch grains block the acid growth response in roots. 
D)  starch is converted to auxin, which causes the downward bending in roots.

Question 14

The signaling molecule for flowering might be released earlier than usual in a long-day plant exposed to flashes of

Accepted Answer

A)  far-red light during the night. 
B)  red light during the night. 
C)  far-red light during the day. 
D)  red light during the day. 
A)  far-red light during the night. 
B)  red light during the night. 
C)  far-red light during the day. 
D)  red light during the day.

Question 15

Plants that have their flowering inhibited by being exposed to bright lights at night are

Accepted Answer

A)  day-neutral plants. 
B)  short-night plants. 
C)  short-day plants. 
D)  long-day plants. 
A)  day-neutral plants. 
B)  short-night plants. 
C)  short-day plants. 
D)  long-day plants.

Question 16

Statoliths are structures that are responsible for

Accepted Answer

A)  phototropism. 
B)  gravitropism. 
C)  thigmotropism. 
D)  dormancy. 
A)  phototropism. 
B)  gravitropism. 
C)  thigmotropism. 
D)  dormancy.

Question 17

Experiments on the positive phototropic response of plants indicate that

Accepted Answer

A)  light destroys auxin. 
B)  auxin moves down the plant apoplastically. 
C)  auxin is synthesized in the area where the stem bends. 
D)  auxin can move to the shady side of the stem. 
A)  light destroys auxin. 
B)  auxin moves down the plant apoplastically. 
C)  auxin is synthesized in the area where the stem bends. 
D)  auxin can move to the shady side of the stem.

Question 18

The aleurone layer is stimulated to release ________ as a result of gibberellin release from the embryo.

Accepted Answer

A)  amino acids 
B)  carbohydrates 
C)  cytokinins 
D)  amylase 
A)  amino acids 
B)  carbohydrates 
C)  cytokinins 
D)  amylase

Question 19

The application of which of the following hormones would be a logical first choice in an attempt to produce normal growth in mutant dwarf plants?

Accepted Answer

A)  indoleacetic acid 
B)  cytokinin 
C)  gibberellin 
D)  abscisic acid 
A)  indoleacetic acid 
B)  cytokinin 
C)  gibberellin 
D)  abscisic acid

Question 20

How does indoleacetic acid affect fruit development?

Accepted Answer

A)  by preventing pollination 
B)  by inhibiting formation of the ovule 
C)  by promoting gene expression in cambial tissue 
D)  by promoting rapid growth of the ovary 
A)  by preventing pollination 
B)  by inhibiting formation of the ovule 
C)  by promoting gene expression in cambial tissue 
D)  by promoting rapid growth of the ovary

Exam 31: Plant Responses to Internal and External Signals

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

Figure 31.1 The heavy line in Figure 31.1 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(s) would probably be produced?

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

Which of the following treatments would enhance the level of the Pfr form of phytochrome?

Plant hormones can have different effects at different concentrations. This explains how

Which of the following statements best summarizes the acid growth hypothesis in an actively growing shoot?

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

When an arborist prunes a limb off a valuable tree, he or she usually paints the cut surface. The primary purpose of the paint is to

Figure 31.2 -This experiment suggests that the unknown amount of gibberellin in the experimental plant (B) is approximately

________ promote(s) stomatal closure in plant leaves during drought stress.

What do the results of research on gravitropic responses of roots and stems show?

In an experiment, a plant physiologist has four groups of bananas of the same species. He exposes each of the four groups of bananas with the same concentration of auxins, gibberellins, abscisic acid, or ethylene. Which of these four groups of bananas ripen the fastest?

A botanist discovers a plant that lacks the ability to form starch grains in root cells, yet the roots still grow downward. This evidence refutes the long-standing hypothesis that

The signaling molecule for flowering might be released earlier than usual in a long-day plant exposed to flashes of

Plants that have their flowering inhibited by being exposed to bright lights at night are

Statoliths are structures that are responsible for

Experiments on the positive phototropic response of plants indicate that

The aleurone layer is stimulated to release ________ as a result of gibberellin release from the embryo.

The application of which of the following hormones would be a logical first choice in an attempt to produce normal growth in mutant dwarf plants?

How does indoleacetic acid affect fruit development?

Introduction: Evolution and the Foundations of Biology

The Chemical Context of Life

Carbon and the Molecular Diversity of Life

A Tour of the Cell

Membrane Transport and Cell Signaling

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

Gene Expression: From Gene to Protein

Regulation of Gene Expression

Development, Stem Cells, and Cancer

Viruses

Genomes and Their Evolution

Descent With Modification

Phylogeny

The Evolution of Populations

The Origin of Species

Broad Patterns of Evolution

Early Life and the Diversification of Prokaryotes

The Origin and Diversification of Eukaryotes

The Colonization of Land by Plants and Fungi

The Rise of Animal Diversity

Plant Structure and Growth

Resource Acquisition, Nutrition, and Transport in Vascular Plants

Reproduction and Domestication of Flowering Plants

Homeostasis and Endocrine Signaling

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Reproduction and Development

Neurons, Synapses, and Signaling

Nervous and Sensory Systems

Motor Mechanisms and Behavior

Population Ecology and the Distribution of Organisms

Species Interactions

Ecosystems and Energy

Global Ecology and Conservation Biology

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