Question 1

The most reliable way to stimulate branching in a plant is to

Accepted Answer

A)  apply auxin to the roots. 
B)  remove the terminal bud. 
C)  give short-day light treatments. 
D)  add extra fertilizer. 
A)  apply auxin to the roots. 
B)  remove the terminal bud. 
C)  give short-day light treatments. 
D)  add extra fertilizer. B

Question 2

What is one adaptive advantage for deciduous plants that lose their leaves during the winter?

Accepted Answer

A)  It prevents water loss from leaves when soil water is unavailable due to freezing. 
B)  Production of new leaves each spring uses less energy than supporting old leaves all winter. 
C)  If leaves are damaged by frost, the tree will die. 
D)  A layer of leaves on the ground helps keep plant roots warm. 
A)  It prevents water loss from leaves when soil water is unavailable due to freezing. 
B)  Production of new leaves each spring uses less energy than supporting old leaves all winter. 
C)  If leaves are damaged by frost, the tree will die. 
D)  A layer of leaves on the ground helps keep plant roots warm. A

Question 3

Which statement about plant hormones is true?

Accepted Answer

A)  Plant hormones are produced in very small concentrations. 
B)  Plant hormones mainly affect reproductive processes. 
C)  A hormone typically has a single, specific effect on all cells. 
D)  Plant hormones play a vital role in photosynthesis. 
A)  Plant hormones are produced in very small concentrations. 
B)  Plant hormones mainly affect reproductive processes. 
C)  A hormone typically has a single, specific effect on all cells. 
D)  Plant hormones play a vital role in photosynthesis. A

Question 4

There is concern over the use of 2,4-D, a synthetic plant hormone, as a weed killer because the by-product dioxin

Accepted Answer

A)  can cause irreversible mutations in crop plants. 
B)  causes fruit to drop prematurely from plants. 
C)  can cause birth defects and leukemia in mammals. 
D)  weakens the shells of the eggs of predatory birds, resulting in the death of their offspring. 
A)  can cause irreversible mutations in crop plants. 
B)  causes fruit to drop prematurely from plants. 
C)  can cause birth defects and leukemia in mammals. 
D)  weakens the shells of the eggs of predatory birds, resulting in the death of their offspring.

Question 5

About how many gibberellins have been identified in plants?

Accepted Answer

A)  one 
B)  five 
C)  over one hundred 
D)  thousands 
A)  one 
B)  five 
C)  over one hundred 
D)  thousands

Question 6

A student taking a plant physiology class is interested in investigating what will happen if the apical bud is removed from a growing plant and supplementary hormones are introduced.
He set up his experiment with two groups of plants of the same species. In groups A and B, the apical buds were removed and the cut apical ends were wrapped with hormone-impregnated cotton. The plants were observed over a 5-week period for growth and development. In group A, many axillary buds and leaves appeared along the sides of the stem, and the plants had minimal root growth. In group B, minimal growth occurred in the shoot and roots, and no axillary buds formed.
-What hormone was in the cotton used to wrap the apical ends of the group B plants?

Accepted Answer

A)  cytokinin 
B)  giberellin 
C)  abscisic acid 
D)  auxin 
A)  cytokinin 
B)  giberellin 
C)  abscisic acid 
D)  auxin

Question 7

-Which statement is supported by this figure?

Accepted Answer

A)  The greater the concentration of auxin, the more promotion of root elongation occurs. 
B)  Auxin concentrations below 10−8 g/L promote both root and stem elongation. 
C)  Auxin concentrations around 10−4 g/L promote stem elongation but inhibit root elongation. 
D)  Auxin concentrations above 0.9 g/L are best for promoting stem elongation. 
A)  The greater the concentration of auxin, the more promotion of root elongation occurs. 
B)  Auxin concentrations below 10−8 g/L promote both root and stem elongation. 
C)  Auxin concentrations around 10−4 g/L promote stem elongation but inhibit root elongation. 
D)  Auxin concentrations above 0.9 g/L are best for promoting stem elongation.

Question 8

What dense storage granules in plant cells are thought to contribute to gravitropism?

Accepted Answer

A)  starch 
B)  glucose 
C)  proteins 
D)  chlorophyll 
A)  starch 
B)  glucose 
C)  proteins 
D)  chlorophyll

Question 9

What term refers to seasonal changes in the relative lengths of night and day?

Accepted Answer

A)  photoperiod 
B)  circadian rhythm 
C)  gravitropism 
D)  phototropism 
A)  photoperiod 
B)  circadian rhythm 
C)  gravitropism 
D)  phototropism

Question 10

In many grocery stores, fresh fruits are sold in plastic bags dotted with holes so that they will not overripen. The main function of the holes is to

Accepted Answer

A)  permit the fruit to drain after being washed. 
B)  facilitate diffusion of ethylene away from the fruit. 
C)  prevent buildup of CO2. 
D)  facilitate diffusion of O2 to the fruit. 
A)  permit the fruit to drain after being washed. 
B)  facilitate diffusion of ethylene away from the fruit. 
C)  prevent buildup of CO2. 
D)  facilitate diffusion of O2 to the fruit.

Question 11

A plant will only flower if the night length is longer than 14 hours. This plant is a

Accepted Answer

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

Question 12

A plant's first line of defense against infection is

Accepted Answer

A)  cell elongation. 
B)  its epidermis. 
C)  phytochrome. 
D)  salicylic acid. 
A)  cell elongation. 
B)  its epidermis. 
C)  phytochrome. 
D)  salicylic acid.

Question 13

Which process underlies the thigmotropic behavior of a green bean tendril?

Accepted Answer

A)  rotation of the tendril in response to photoperiod 
B)  rotation of the tendril in response to a biological clock 
C)  extra proliferation of cells on the shaded side of the tendril 
D)  slower growth on the side where an object is touching the tendril 
A)  rotation of the tendril in response to photoperiod 
B)  rotation of the tendril in response to a biological clock 
C)  extra proliferation of cells on the shaded side of the tendril 
D)  slower growth on the side where an object is touching the tendril

Question 14

Which plant response is affected by photoperiod?

Accepted Answer

A)  gravitropism 
B)  apical dominance 
C)  onset of dormancy 
D)  cell division 
A)  gravitropism 
B)  apical dominance 
C)  onset of dormancy 
D)  cell division

Question 15

One experiment in phototropism involved cutting off the tips of grass seedlings before exposing them to light from one side. The decapitated seedlings did not bend toward the light. A valid conclusion from this experiment would be that

Accepted Answer

A)  plants cannot engage in photosynthesis without the tip of the plant. 
B)  light is perceived by the tip of grass plants. 
C)  a foil cover over the tip of the seedlings would cause them to bend. 
D)  hormones are produced in all parts of the plant. 
A)  plants cannot engage in photosynthesis without the tip of the plant. 
B)  light is perceived by the tip of grass plants. 
C)  a foil cover over the tip of the seedlings would cause them to bend. 
D)  hormones are produced in all parts of the plant.

Question 16

Plant hormones

Accepted Answer

A)  must be produced in large quantities to be effective. 
B)  act on all cells they encounter. 
C)  are chemical signals that influence growth and development. 
D)  are rare and produced only in response to stress. 
A)  must be produced in large quantities to be effective. 
B)  act on all cells they encounter. 
C)  are chemical signals that influence growth and development. 
D)  are rare and produced only in response to stress.

Question 17

If the auxin that is produced by an apical meristem is transported in equal amounts down all sides of a twig, the twig will probably

Accepted Answer

A)  elongate evenly. 
B)  branch near its tip. 
C)  flower. 
D)  bend away from the apical meristem. 
A)  elongate evenly. 
B)  branch near its tip. 
C)  flower. 
D)  bend away from the apical meristem.

Question 18

What is one main effect of auxins on plant growth?

Accepted Answer

A)  They reduce growth by inducing leaves to fall. 
B)  They increase growth by promoting cell elongation. 
C)  They increase growth by increasing the rate of photosynthesis. 
D)  Auxins have no effect on plant growth. 
A)  They reduce growth by inducing leaves to fall. 
B)  They increase growth by promoting cell elongation. 
C)  They increase growth by increasing the rate of photosynthesis. 
D)  Auxins have no effect on plant growth.

Question 19

Ethylene triggers the ripening of fruit for many plant species but does not seem to play an important role for the ripening of grapes. Scientists hypothesized that the trigger for the ripening of grape fruits is abscisic acid (ABA). They sprayed unripe Cabernet Sauvignon grapes with different concentrations of ABA and tracked several fruit characteristics over time: percent of fruits that are purple, concentration of anthocyanin (a purple pigment) per fruit, weight of each fruit, and total soluble solids per fruit as measured by °Brix. °Brix measurements indicate the amount of sugar in the fruit, and determine how much alcohol a wine will have. Higher values of each measurement indicate a greater degree of ripening. The scientists' results are shown in these four graphs.
   Source: Wheeler, S., Loveys, B., Ford, C., & Davies, C. (2009). The relationship between the expression of abscisic acid biosynthesis genes, accumulation of abscisic acid and the promotion of Vitis vinifera L. berry ripening by abscisic acid. Australian Journal of Grape and Wine Research, 15(3), 195-204.
-The visual indicator for grape ripening is the color of the fruit. Does adding ABA appear to speed up the ripening of grape fruit?

Accepted Answer

A)  Yes, because fruits that were treated with ABA have more anthocyanin (purple pigment) earlier than the control. 
B)  Yes, because there were always more colored fruits in both ABA treatments compared to the control. 
C)  No, because fruits in all the treatments were colored by the end of the experiment. 
D)  No, because fruits in all the treatments have similar amounts of anthocyanin (purple pigment) by the end of the experiment. 
A)  Yes, because fruits that were treated with ABA have more anthocyanin (purple pigment) earlier than the control. 
B)  Yes, because there were always more colored fruits in both ABA treatments compared to the control. 
C)  No, because fruits in all the treatments were colored by the end of the experiment. 
D)  No, because fruits in all the treatments have similar amounts of anthocyanin (purple pigment) by the end of the experiment.

Question 20

Ethylene triggers the ripening of fruit for many plant species but does not seem to play an important role for the ripening of grapes. Scientists hypothesized that the trigger for the ripening of grape fruits is abscisic acid (ABA). They sprayed unripe Cabernet Sauvignon grapes with different concentrations of ABA and tracked several fruit characteristics over time: percent of fruits that are purple, concentration of anthocyanin (a purple pigment) per fruit, weight of each fruit, and total soluble solids per fruit as measured by °Brix. °Brix measurements indicate the amount of sugar in the fruit, and determine how much alcohol a wine will have. Higher values of each measurement indicate a greater degree of ripening. The scientists' results are shown in these four graphs.
   Source: Wheeler, S., Loveys, B., Ford, C., & Davies, C. (2009). The relationship between the expression of abscisic acid biosynthesis genes, accumulation of abscisic acid and the promotion of Vitis vinifera L. berry ripening by abscisic acid. Australian Journal of Grape and Wine Research, 15(3), 195-204.
-What is the difference between fruits sprayed with the low (5 mg/L) concentration of ABA and the high (400 mg/L) concentration of ABA?

Accepted Answer

A)  The high concentration results in the earlier occurrence of colored fruit and maximum fruit size. 
B)  The high concentration induces an earlier occurrence of the maximum amount of anthocyanin (purple pigment). 
C)  The high concentration has smaller fruit until the end of the experiment. 
D)  The high concentration produces fruit with less sugar at the end of the experiment. 
A)  The high concentration results in the earlier occurrence of colored fruit and maximum fruit size. 
B)  The high concentration induces an earlier occurrence of the maximum amount of anthocyanin (purple pigment). 
C)  The high concentration has smaller fruit until the end of the experiment. 
D)  The high concentration produces fruit with less sugar at the end of the experiment.

Exam 33: Control Systems in Plants

The most reliable way to stimulate branching in a plant is to

What is one adaptive advantage for deciduous plants that lose their leaves during the winter?

Which statement about plant hormones is true?

There is concern over the use of 2,4-D, a synthetic plant hormone, as a weed killer because the by-product dioxin

About how many gibberellins have been identified in plants?

-Which statement is supported by this figure?

What dense storage granules in plant cells are thought to contribute to gravitropism?

What term refers to seasonal changes in the relative lengths of night and day?

In many grocery stores, fresh fruits are sold in plastic bags dotted with holes so that they will not overripen. The main function of the holes is to

A plant will only flower if the night length is longer than 14 hours. This plant is a

A plant's first line of defense against infection is

Which process underlies the thigmotropic behavior of a green bean tendril?

Which plant response is affected by photoperiod?

One experiment in phototropism involved cutting off the tips of grass seedlings before exposing them to light from one side. The decapitated seedlings did not bend toward the light. A valid conclusion from this experiment would be that

Plant hormones

If the auxin that is produced by an apical meristem is transported in equal amounts down all sides of a twig, the twig will probably

What is one main effect of auxins on plant growth?

Biology: Exploring Life

The Chemical Basis of Life

The Molecules of Cells

A Tour of the Cell

The Working Cell

How Cells Harvest Chemical Energy

Photosynthesis: Using Light to Make Food

The Cellular Basis of Reproduction and Inheritance

Patterns of Inheritance

Molecular Biology of the Gene

How Genes Are Controlled

DNA Technology and Genomics

How Populations Evolve

The Origin of Species

Tracing Evolutionary History

Microbial Life: Prokaryotes and Protists

The Evolution of Plant and Fungal Diversity

The Evolution of Invertebrate Diversity

The Evolution of Vertebrate Diversity

Unifying Concepts of Animal Structure and Function

Nutrition and Digestion

Gas Exchange

Circulation

The Immune System

Control of Body Temperature and Water Balance

Hormones and the Endocrine System

Reproduction and Embryonic Development

Nervous Systems

The Senses

How Animals Move

Plant Structure, Growth, and Reproduction

Plant Nutrition and Transport

The Biosphere: an Introduction to Earths Diverse Environments

Behavioral Adaptations to the Environment

Population Ecology

Communities and Ecosystems

Conservation Biology

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