Question 1

Auxin enhances cell elongation in all of these ways except

Accepted Answer

A)  increased uptake of solutes. 
B)  gene activation. 
C)  acid-induced denaturation of cell wall proteins. 
D)  increased activity of plasma membrane proton pumps. 
E)  cell wall loosening. 
A)  increased uptake of solutes. 
B)  gene activation. 
C)  acid-induced denaturation of cell wall proteins. 
D)  increased activity of plasma membrane proton pumps. 
E)  cell wall loosening. C

Question 2

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

Question 3

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

Question 4

A botanist exposed two groups of the same plant species to two photoperiods-one with 14 hours of light and 10 hours of dark and the other with 10 hours of light and 14 hours of dark. Under the first set of conditions, the plants flowered, but they failed to flower under the second set of conditions. Which of the following conclusions would be consistent with these results?

Accepted Answer

A)  The critical night length is 14 hours. 
B)  The plants are short-day plants. 
C)  The critical day length is 10 hours. 
D)  The plants can convert phytochrome to florigen. 
E)  The plants flower in the late spring. 
A)  The critical night length is 14 hours. 
B)  The plants are short-day plants. 
C)  The critical day length is 10 hours. 
D)  The plants can convert phytochrome to florigen. 
E)  The plants flower in the late spring.

Question 5

Seed packets give a recommended planting depth for the enclosed seeds. The most likely reason some seeds are to be covered with only ¼ inch of soil is that the

Accepted Answer

A)  seedlings do not produce a hypocotyl. 
B)  seedlings do not have an etiolation response. 
C)  seeds require light to germinate. 
D)  seeds require a higher temperature to germinate. 
E)  seeds are very sensitive to waterlogging. 
A)  seedlings do not produce a hypocotyl. 
B)  seedlings do not have an etiolation response. 
C)  seeds require light to germinate. 
D)  seeds require a higher temperature to germinate. 
E)  seeds are very sensitive to waterlogging.

Question 6

Which of the following is the most likely plant response to an attack by herbivores?

Accepted Answer

A)  leaf abscission to prevent further loss 
B)  early flowering to try to reproduce before being eaten 
C)  production of chemical compounds for defense or to attract predators 
D)  production of physical defenses, such as thorns 
E)  production of thicker bark and cuticle to make it more difficult to eat 
A)  leaf abscission to prevent further loss 
B)  early flowering to try to reproduce before being eaten 
C)  production of chemical compounds for defense or to attract predators 
D)  production of physical defenses, such as thorns 
E)  production of thicker bark and cuticle to make it more difficult to eat

Question 7

Which of the following statements applies to plant growth regulators?

Accepted Answer

A)  They only act by altering gene expression. 
B)  They often have a multiplicity of effects. 
C)  They function independently of other hormones. 
D)  They directly control plant protein synthesis and assembly. 
E)  They affect the division and elongation, but not the differentiation, of cells. 
A)  They only act by altering gene expression. 
B)  They often have a multiplicity of effects. 
C)  They function independently of other hormones. 
D)  They directly control plant protein synthesis and assembly. 
E)  They affect the division and elongation, but not the differentiation, of cells.

Question 8

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 9

Classic experiments suggested that a floral stimulus, florigen, could move across a graft from an induced plant to a noninduced plant and trigger flowering. Recent evidence using Arabidopsis has recently shown that florigen is probably

Accepted Answer

A)  a phytochrome molecule that is activated by red light. 
B)  a protein that is synthesized in leaves, travels to the shoot apical meristems, and initiates flowering. 
C)  a membrane signal that travels through the symplast from leaves to buds. 
D)  a second messenger that induces Ca++ ions to change membrane potential. 
E)  a transcription factor that controls the activation of florigen-specific genes. 
A)  a phytochrome molecule that is activated by red light. 
B)  a protein that is synthesized in leaves, travels to the shoot apical meristems, and initiates flowering. 
C)  a membrane signal that travels through the symplast from leaves to buds. 
D)  a second messenger that induces Ca++ ions to change membrane potential. 
E)  a transcription factor that controls the activation of florigen-specific genes.

Question 10

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. 
E)  equal to the amount of gibberellin in the shortest plant. 
A)  zero. 
B)  0.01 μg/mL. 
C)  0.1 μg/mL. 
D)  1.0 μg/mL. 
E)  equal to the amount of gibberellin in the shortest plant.

Question 11

A plant mutant that showed normal gravitropic bending but did not store starch in its plastids would require a reevaluation of the role of ________ in gravitropism.

Accepted Answer

A)  auxin 
B)  calcium 
C)  statoliths 
D)  light 
E)  differential growth 
A)  auxin 
B)  calcium 
C)  statoliths 
D)  light 
E)  differential growth

Question 12

The biological clock controlling circadian rhythms must ultimately

Accepted Answer

A)  depend on environmental cues. 
B)  affect gene transcription. 
C)  stabilize on a 24-hour cycle. 
D)  speed up or slow down with increasing or decreasing temperature. 
E)  do all of the above. 
A)  depend on environmental cues. 
B)  affect gene transcription. 
C)  stabilize on a 24-hour cycle. 
D)  speed up or slow down with increasing or decreasing temperature. 
E)  do all of the above.

Question 13

Which of the following best explains both the growth of a vine up the trunk of a tree as well as the directional growth of a houseplant toward a window?

Accepted Answer

A)  nastic movement 
B)  taxic movement 
C)  tropism response 
D)  morphological response 
E)  acclimation 
A)  nastic movement 
B)  taxic movement 
C)  tropism response 
D)  morphological response 
E)  acclimation

Question 14

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 15

In legumes, it has been shown that "sleep" (nastic) movements are correlated with

Accepted Answer

A)  positive thigmotropisms. 
B)  rhythmic opening and closing of K+ channels in motor cell membranes. 
C)  senescence (the aging process in plants). 
D)  flowering and fruit development. 
E)  ABA-stimulated closing of guard cells caused by loss of K+. 
A)  positive thigmotropisms. 
B)  rhythmic opening and closing of K+ channels in motor cell membranes. 
C)  senescence (the aging process in plants). 
D)  flowering and fruit development. 
E)  ABA-stimulated closing of guard cells caused by loss of K+.

Question 16

Which of the following hormones would be most useful in promoting the rooting of plant cuttings?

Accepted Answer

A)  strigolactones 
B)  abscisic acid 
C)  cytokinins 
D)  gibberellins 
E)  indolebutyric acid 
A)  strigolactones 
B)  abscisic acid 
C)  cytokinins 
D)  gibberellins 
E)  indolebutyric acid

Question 17

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)  devoid of phytochrome. 
D)  short-day plants. 
E)  long-day plants. 
A)  day-neutral plants. 
B)  short-night plants. 
C)  devoid of phytochrome. 
D)  short-day plants. 
E)  long-day plants.

Question 18

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. 
E)  Auxins and gibberellins are transported to the vacuoles to build up turgor pressure. 
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. 
E)  Auxins and gibberellins are transported to the vacuoles to build up turgor pressure.

Question 19

Why do coleoptiles grow toward light?

Accepted Answer

A)  Auxin is destroyed by light. 
B)  Gibberellins are destroyed by light. 
C)  Auxin synthesis is stimulated in the dark. 
D)  Auxin moves away from the light to the shady side. 
E)  Gibberellins move away from the light to the shady side. 
A)  Auxin is destroyed by light. 
B)  Gibberellins are destroyed by light. 
C)  Auxin synthesis is stimulated in the dark. 
D)  Auxin moves away from the light to the shady side. 
E)  Gibberellins move away from the light to the shady side.

Question 20

Why are axillary buds often inhibited from growing even though a stem may be actively elongating?

Accepted Answer

A)  The cells of axillary buds respond differently to auxin than stem cells. 
B)  Axillary buds are high in abscisic acid that prevents elongation. 
C)  Axillary buds are low in gibberellins. 
D)  Stem cells lack receptors for auxin. 
E)  Stem cells can overcome auxin inhibition with high levels of gibberellins. 
A)  The cells of axillary buds respond differently to auxin than stem cells. 
B)  Axillary buds are high in abscisic acid that prevents elongation. 
C)  Axillary buds are low in gibberellins. 
D)  Stem cells lack receptors for auxin. 
E)  Stem cells can overcome auxin inhibition with high levels of gibberellins.

Exam 31: Plant Responses to Internal and External Signals

Auxin enhances cell elongation in all of these ways except

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

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

Seed packets give a recommended planting depth for the enclosed seeds. The most likely reason some seeds are to be covered with only ¼ inch of soil is that the

Which of the following is the most likely plant response to an attack by herbivores?

Which of the following statements applies to plant growth regulators?

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

Classic experiments suggested that a floral stimulus, florigen, could move across a graft from an induced plant to a noninduced plant and trigger flowering. Recent evidence using Arabidopsis has recently shown that florigen is probably

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

A plant mutant that showed normal gravitropic bending but did not store starch in its plastids would require a reevaluation of the role of ________ in gravitropism.

The biological clock controlling circadian rhythms must ultimately

Which of the following best explains both the growth of a vine up the trunk of a tree as well as the directional growth of a houseplant toward a window?

The hormone that helps plants respond to drought is

In legumes, it has been shown that "sleep" (nastic) movements are correlated with

Which of the following hormones would be most useful in promoting the rooting of plant cuttings?

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

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

Why do coleoptiles grow toward light?

Why are axillary buds often inhibited from growing even though a stem may be actively elongating?

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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