Question 1

Which class of hormones produced in the roots of plants promotes cell division and growth and retards the aging of flowers and leaves?

Accepted Answer

A)  gibberellins 
B)  phytochromes 
C)  cytokinins 
D)  ethylene 
A)  gibberellins 
B)  phytochromes 
C)  cytokinins 
D)  ethylene

Question 2

Iris is a long-day plant that normally flowers in the spring. Which regimen would be the most effective in making an iris bloom in late fall?

Accepted Answer

A)  interrupting the plant's nights at 2:00 am with a flash of far-red light 
B)  interrupting the plant's nights at 2:00 am with a flash of red light followed by a flash of far-red light 
C)  interrupting the plant's nights at 2:00 am with a red flash, then a far-red flash, then a red flash 
D)  interrupting the plant's days at 2:00 pm by putting it in the dark 
A)  interrupting the plant's nights at 2:00 am with a flash of far-red light 
B)  interrupting the plant's nights at 2:00 am with a flash of red light followed by a flash of far-red light 
C)  interrupting the plant's nights at 2:00 am with a red flash, then a far-red flash, then a red flash 
D)  interrupting the plant's days at 2:00 pm by putting it in the dark

Question 3

Which type of plant hormone generally acts as a growth inhibitor?

Accepted Answer

A)  auxins 
B)  gibberellins 
C)  cytokinins 
D)  abscisic acid (AB
A)  
A)  auxins 
B)  gibberellins 
C)  cytokinins 
D)  abscisic acid (AB
A)

Question 4

What stimulates germination of desert plant seeds after a hard rain?

Accepted Answer

A)  production of auxins 
B)  removal of abscisic acid 
C)  cooler temperatures 
D)  activation of cytokinins 
A)  production of auxins 
B)  removal of abscisic acid 
C)  cooler temperatures 
D)  activation of cytokinins

Question 5

Citrus fruit has always been distributed from areas where the fruit is grown to other parts of the country, often by train. In the early 1900s train cars were heated with coal, and it was believed that this heat helped ripen the fruit. Imagine the surprise of growers and suppliers when fruit that arrived in new boxcars heated by steam arrived unripe. Why did the fruit no longer ripen?

Accepted Answer

A)  The length of time needed to ripen the fruit was met by slow-moving older trains; newer steam-powered locomotives arrived before the fruit ripened. 
B)  Ethylene, a by-product of coal burning, ripened the fruit in the cars with the coal stove but was absent from the steam-powered trains. 
C)  The light from the coal-burning stoves caused the fruits to experience short nights, so without this light, they no longer ripened. 
D)  The steam prevented the buildup of abscisic acid, which is needed to ripen fruit. 
A)  The length of time needed to ripen the fruit was met by slow-moving older trains; newer steam-powered locomotives arrived before the fruit ripened. 
B)  Ethylene, a by-product of coal burning, ripened the fruit in the cars with the coal stove but was absent from the steam-powered trains. 
C)  The light from the coal-burning stoves caused the fruits to experience short nights, so without this light, they no longer ripened. 
D)  The steam prevented the buildup of abscisic acid, which is needed to ripen fruit.

Question 6

How does phytochrome control flowering?

Accepted Answer

A)  by disrupting the plant's photoperiod 
B)  by detecting differences in temperature in the spring 
C)  by sensing sunrise and sunset 
D)  by inducing differentiation of cells in the apical meristem 
A)  by disrupting the plant's photoperiod 
B)  by detecting differences in temperature in the spring 
C)  by sensing sunrise and sunset 
D)  by inducing differentiation of cells in the apical meristem

Question 7

-In addition to demonstrating that auxin stimulates elongation, this diagram also shows that

Accepted Answer

A)  application of additional auxin causes greater bending. 
B)  the application of auxin causes growth. 
C)  removing shoot tips also removes auxin receptors. 
D)  the lower parts of the shoot are able to detect light. 
A)  application of additional auxin causes greater bending. 
B)  the application of auxin causes growth. 
C)  removing shoot tips also removes auxin receptors. 
D)  the lower parts of the shoot are able to detect light.

Question 8

What is one way that plants use animals as a defense against herbivores?

Accepted Answer

A)  production of an amino acid that harms herbivores 
B)  attraction of wasps that kill herbivorous caterpillars 
C)  release of microbe-killing chemicals in response to infection 
D)  coevolution between plants and predators 
A)  production of an amino acid that harms herbivores 
B)  attraction of wasps that kill herbivorous caterpillars 
C)  release of microbe-killing chemicals in response to infection 
D)  coevolution between plants and predators

Question 9

Under what conditions would you expect a plant to have the highest concentration of abscisic acid (ABA)?

Accepted Answer

A)  wet tropical rain forest 
B)  cool environment after a heavy rain 
C)  houseplant growing in low light conditions 
D)  desert after a long drought 
A)  wet tropical rain forest 
B)  cool environment after a heavy rain 
C)  houseplant growing in low light conditions 
D)  desert after a long drought

Question 10

Bush beans grow as small bushes rather than as vines because their internodes are short and they branch close to the apical meristem. Which substance, if applied to a bush bean, might cause it to elongate its internodes and grow as a vine?

Accepted Answer

A)  a cytokinin 
B)  a gibberellin 
C)  abscisic acid (AB
A)  
D)  ethylene 
A)  a cytokinin 
B)  a gibberellin 
C)  abscisic acid (AB
A)  
D)  ethylene

Question 11

-If you cut off the top of a carrot and place it in water to see if you can get it to grow new roots, you should add

Accepted Answer

A)  more than 10−2 g/L of auxin. 
B)  approximately 10−8 g/L of auxin. 
C)  at least 10−4 g/L of auxin. 
D)  equal amounts of auxin and cytokinin. 
A)  more than 10−2 g/L of auxin. 
B)  approximately 10−8 g/L of auxin. 
C)  at least 10−4 g/L of auxin. 
D)  equal amounts of auxin and cytokinin.

Question 12

The event that triggers fruit formation is the growth of a pollen tube through the carpel of a flower. Identify a reasonable hypothesis about the basis of this effect.

Accepted Answer

A)  Pollen tubes grow in response to a cytokinin produced by the carpel. 
B)  Pollen tubes grow in response to abscisic acid. 
C)  The growing pollen tube produces ethylene. 
D)  The growing pollen tube produces auxins and/or gibberellins. 
A)  Pollen tubes grow in response to a cytokinin produced by the carpel. 
B)  Pollen tubes grow in response to abscisic acid. 
C)  The growing pollen tube produces ethylene. 
D)  The growing pollen tube produces auxins and/or gibberellins.

Question 13

Mimosa plants spread their leaflets during the day and fold them at night. You decide to design an experiment to test whether Mimosa's leaf movements are controlled by a biological clock. Which experiment would be the best test of your hypothesis?

Accepted Answer

A)  Growing the plant indoors and turning the lights on in the middle of the night. If a biological clock is controlling leaf movement, the leaves will open. 
B)  Putting the plant under a bright light in the middle of the day. If the leaves close, a biological clock mechanism is ruled out. 
C)  Subjecting the plant to a flash of red light in the middle of the night. If the leaves open at the usual time the next morning, a biological clock mechanism is ruled out. 
D)  Putting the plant in a dark closet at nightfall. Check on the plant at noon the next day, while the plant is still in the closet. If the leaves are open, a biological clock is indicated. 
A)  Growing the plant indoors and turning the lights on in the middle of the night. If a biological clock is controlling leaf movement, the leaves will open. 
B)  Putting the plant under a bright light in the middle of the day. If the leaves close, a biological clock mechanism is ruled out. 
C)  Subjecting the plant to a flash of red light in the middle of the night. If the leaves open at the usual time the next morning, a biological clock mechanism is ruled out. 
D)  Putting the plant in a dark closet at nightfall. Check on the plant at noon the next day, while the plant is still in the closet. If the leaves are open, a biological clock is indicated.

Question 14

Fruit that forms on an unpollinated plant in response to a hormone will lack

Accepted Answer

A)  flavor. 
B)  seeds. 
C)  rind. 
D)  naturally occurring hormones. 
A)  flavor. 
B)  seeds. 
C)  rind. 
D)  naturally occurring hormones.

Question 15

Plants grow toward light through the action of

Accepted Answer

A)  hormones. 
B)  nerves. 
C)  phytochrome. 
D)  chloroplasts. 
A)  hormones. 
B)  nerves. 
C)  phytochrome. 
D)  chloroplasts.

Question 16

Synthetic auxins are used commercially

Accepted Answer

A)  to promote seed germination. 
B)  to promote flowering in ornamental crops. 
C)  to promote side branching to produce bushier crops. 
D)  as a broadleaf weed killer. 
A)  to promote seed germination. 
B)  to promote flowering in ornamental crops. 
C)  to promote side branching to produce bushier crops. 
D)  as a broadleaf weed killer.

Question 17

A student wanted to plant an avocado seed to try to grow an avocado plant, but she could not tell which end of the seed was the bottom and which was the top. She asked her friends what she should do. Which friend's suggestion will have the highest success of growing the avocado plant?

Accepted Answer

A)  One friend said it doesn't matter in which direction the seed is planted as long as there is a strong light on the soil, since the shoots will seek the light and turn the seed right side up. 
B)  One friend said to put the seed in in any direction, because as the seed is watered, it will be able to detect the direction the water is coming from and point the shoots that way. 
C)  One friend suggested a compromise: Put the seed sideways, since gravity will ensure that the shoots grow up and the roots grow down. 
D)  One friend said just to put the seed in one direction or the other, because it will only sprout if it is in the right direction, and there's a fifty-fifty chance that it will be in the right orientation. 
A)  One friend said it doesn't matter in which direction the seed is planted as long as there is a strong light on the soil, since the shoots will seek the light and turn the seed right side up. 
B)  One friend said to put the seed in in any direction, because as the seed is watered, it will be able to detect the direction the water is coming from and point the shoots that way. 
C)  One friend suggested a compromise: Put the seed sideways, since gravity will ensure that the shoots grow up and the roots grow down. 
D)  One friend said just to put the seed in one direction or the other, because it will only sprout if it is in the right direction, and there's a fifty-fifty chance that it will be in the right orientation.

Question 18

Which growth response causes the shoots of a plant grown in the dark to grow upward?

Accepted Answer

A)  phototropism 
B)  thigmotropism 
C)  gravitropism 
A)  phototropism 
B)  thigmotropism 
C)  gravitropism

Question 19

What initiates flowering in long-day plants?

Accepted Answer

A)  nights shorter than a critical length 
B)  nights longer than a critical length 
C)  days longer than the nights that are in between them 
D)  days shorter than a critical length 
A)  nights shorter than a critical length 
B)  nights longer than a critical length 
C)  days longer than the nights that are in between them 
D)  days shorter than a critical length

Question 20

Which substance might induce seeds treated with it to break dormancy?

Accepted Answer

A)  an auxin 
B)  a cytokinin 
C)  a gibberellin 
D)  ethylene 
A)  an auxin 
B)  a cytokinin 
C)  a gibberellin 
D)  ethylene

Exam 33: Control Systems in Plants

Which class of hormones produced in the roots of plants promotes cell division and growth and retards the aging of flowers and leaves?

Iris is a long-day plant that normally flowers in the spring. Which regimen would be the most effective in making an iris bloom in late fall?

Which type of plant hormone generally acts as a growth inhibitor?

What stimulates germination of desert plant seeds after a hard rain?

How does phytochrome control flowering?

-In addition to demonstrating that auxin stimulates elongation, this diagram also shows that

What is one way that plants use animals as a defense against herbivores?

Under what conditions would you expect a plant to have the highest concentration of abscisic acid (ABA)?

Bush beans grow as small bushes rather than as vines because their internodes are short and they branch close to the apical meristem. Which substance, if applied to a bush bean, might cause it to elongate its internodes and grow as a vine?

-If you cut off the top of a carrot and place it in water to see if you can get it to grow new roots, you should add

The event that triggers fruit formation is the growth of a pollen tube through the carpel of a flower. Identify a reasonable hypothesis about the basis of this effect.

Mimosa plants spread their leaflets during the day and fold them at night. You decide to design an experiment to test whether Mimosa's leaf movements are controlled by a biological clock. Which experiment would be the best test of your hypothesis?

Fruit that forms on an unpollinated plant in response to a hormone will lack

Plants grow toward light through the action of

Synthetic auxins are used commercially

A student wanted to plant an avocado seed to try to grow an avocado plant, but she could not tell which end of the seed was the bottom and which was the top. She asked her friends what she should do. Which friend's suggestion will have the highest success of growing the avocado plant?

Which growth response causes the shoots of a plant grown in the dark to grow upward?

What initiates flowering in long-day plants?

Which substance might induce seeds treated with it to break dormancy?

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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