Deck 45: Plant Responses to the Environment

Question 1

A botanist who wants to stimulate flower formation could treat the plants with:

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

Answer 1

D

Question 2

Tomatoes that are planted upside down still grow upright, displaying:

A)phototropism.
B)lumitropism.
C)gravitropism.
D)amylotropism.
E)thigmotropism.

Answer 2

C

Question 3

Why does removing an overripe, mushy apple from a container of otherwise good apples help preserve the good apples?

A)The overripe apple makes ethylene gas, which can cause the good apples to become overripe.
B)Ethylene production in the good apples is inhibited by the lack of ethylene production in the overripe apple.
C)Chemicals in the overripe apple stimulate the conversion of sugar to starch in the good apples.
D)The production of cytokinins is inhibited in the remaining good apples.
E)Gibberellins help preserve the good apples.

Answer 3

A

Question 4

________ triggers the formation of an abscission layer in leaves and fruits.

A)Auxin
B)Gibberellin
C)Cytokinin
D)Ethylene
E)Abscisic acid

Question 5

Roots grow downward and shoots grow upward due to:

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

Question 6

Why do bananas in a bag ripen so much faster than bananas on a counter top?

A)Ethylene, produced by the fruit, is trapped in the bag.
B)Abscisic acid, produced by the fruit, is trapped in the bag.
C)The bag holds in more moisture.
D)Auxins are present in low concentrations in the bag because sunlight stimulates the production of this hormone.
E)Cytokinins are present in low concentrations in the bag because sunlight stimulates the production of this hormone.

Question 7

If you want to keep cut flowers fresh, treat them with:

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

Question 8

A plant's tendency to grow toward a source of light is called:

A)phototropism.
B)lumitropism.
C)gravitropism.
D)amylotropism.
E)thigmotropism.

Question 9

________ maintains seed dormancy, and ________ ends seed dormancy by stimulating enzymes that break down the food reserves of the seed to fuel seedling growth.

A)Gibberellin; abscisic acid
B)Abscisic acid; gibberellin
C)Auxin; cytokinin
D)Cytokinin; auxin
E)Abscisic acid; ethylene a

Question 10

A scientist who claims to have discovered a new plant hormone must demonstrate that this compound is:

A)produced in large amounts.
B)needed by the plant as a major source of energy.
C)formed in one part of the plant but has an effect in a different part.
D)capable of stimulating differentiated cells to form meristem tissue.
E)made from cell proteins.

Question 11

Why are most carnivorous plants found in bogs?

A)Bogs are naturally high in nitrogen.
B)Bogs are low in nitrogen, and the carnivorous lifestyle provides extra nitrogen.
C)Bogs contain many soil-based proteins, which are a good source of nitrogen.
D)Bogs contain rich populations of nitrogen-fixing bacteria, which provide nitrogen to the plants.

Question 12

After seeds were planted, some of the seedlings did not emerge from the soil. Is it possible that this is because some of the seeds were planted upside down?

A)Yes; if the seed was oriented so that the embryonic shoot pointed down, it would grow in that direction because sunlight doesn't reach it.
B)Yes; after seeds are planted, water and settling of the soil may cause them to shift in their orientation.
C)No; auxins in the shoots cause curvature away from gravity.
D)No; sunlight penetrates soil to the depth of seeds and shoots grow toward the sunlight.
E)No; gibberellins and abscisic acid, in balanced concentrations, cause shoots to grow away from gravity.

Question 13

Pea plant tendrils wrapping around a string demonstrate:

A)phototropism.
B)lumitropism.
C)gravitropism.
D)amylotropism.
E)thigmotropism.

Question 14

Which of these hormones helps plants tolerate drought and cold?

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

Question 15

The synthetic herbicide 2,4-D is actually a(n):

A)cytokinin.
B)ethylene gas.
C)florigen.
D)auxin.
E)gibberellin.

Question 16

How a plant cell responds to a hormone depends on the:

A)cell that secretes the hormone.
B)"shelf life" of the hormone.
C)concentration of the hormone.
D)presence of other plant cells nearby.
E)amount of available sunlight.

Question 17

Gravitropism is a plant's:

A)directional response to gravity.
B)response to stress-inducing situations.
C)ability to grow only upward.
D)ability to form an abscission layer, so that the fruits and leaves fall from the plant.
E)apical dominance.

Question 18

Seed germination is stimulated by:

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

Question 19

Discovered in 2007, the hormones that control the timing of flowering are called:

A)auxins.
B)florigens.
C)cytokinins.
D)ethylenes.
E)abscisic acids.

Question 20

The hormone ________ was named after the fungus that causes "foolish seedling" disease in rice.

A)cytokinin
B)ethylene
C)florigen
D)auxin
E)gibberellin

Question 21

Placing a ripe apple in a bag of green bananas will cause the bananas to ripen quickly. This is because the apple:

A)absorbs cytokinin.
B)forms digestive enzymes.
C)makes auxin.
D)produces ethylene gas.
E)releases heat.

Question 22

The relative sizes of roots and shoots are regulated by interactions between:

A)auxins and cytokinins.
B)abscisic acid and cytokinins.
C)cytokinins and ethylene.
D)ethylene and abscisic acid.
E)gibberellins and abscisic acid.

Question 23

Ethylene:

A)promotes gravitropism.
B)inhibits stem elongation.
C)prevents leaf senescence.
D)stimulates seed germination.
E)causes phototropism.

Question 24

Suppose you have some seeds that refuse to germinate when placed in moist soil. What could you do to encourage the seeds to germinate?

A)Boil them.
B)Treat them with gibberellin.
C)Treat them with auxin.
D)Treat them with abscisic acid.
E)Put them in direct sunlight.

Question 25

Most scientists believe that the lateral buds farthest from the top of a tree are the least inhibited from sprouting because they:

A)receive the least light.
B)receive the most cytokinins from the roots.
C)produce gibberellins.
D)are shaded by the top of the tree.
E)are the most affected by gravity.

Question 26

Which of these hormones causes cell elongation, promotes apical dominance, and stimulates root branching?

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

Question 27

Most scientists believe that the lateral buds nearest the top of a tree are most inhibited from sprouting because they:

A)are most exposed to the light.
B)are shaded by the apical bud and the top of the tree.
C)produce gibberellins.
D)receive the most auxin from the apical bud.
E)are the most affected by gravity.

Question 28

If you were running a tree nursery and wanted to keep your trees dormant until the customer could plant them, which hormone would you spray on the trees?

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

Question 29

Auxin:

A)inhibits stem elongation.
B)promotes phototropism.
C)stimulates flowering.
D)promotes cell division.
E)causes the development of an abscission layer.

Question 30

To encourage the formation of well-developed, heavily branched roots, you should treat cuttings with:

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

Question 31

What will happen to a long-day plant, such as spinach, if the dark period is interrupted by a flash of light for several days in a row during the spring?

A)Nothing will happen; growth and development will continue as normal.
B)The plants will flower early.
C)The plants will be delayed in flowering.
D)The plants won't flower that season.

Question 32

The two hormones involved in seed germination and seed dormancy are:

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

Question 33

Cutting a hedge with a trimmer stimulates it to become bushy because:

A)removing the apical meristems makes more auxin, which stimulates lateral branch buds to grow.
B)removing the apical meristems makes less ethylene, which stimulates lateral branches to grow.
C)removing the apical meristems results in less auxin, which results in more lateral branch growth.
D)removing the lateral buds results in apical dominance under the influence of cytokinins.

Question 34

________ induces dormancy in seeds and buds and causes stomata to close?

A)Auxin
B)Ethylene
C)Abscisic acid
D)Cytokinin
E)Gibberellin

Question 35

Abscisic acid enforces dormancy of seeds by:

A)waterproofing the seed coat.
B)preventing endosperm development.
C)activating gibberellin.
D)preventing the growth of the embryo.
E)binding to the molecule ATP.

Question 36

When auxin accumulates on the lower side of the root of a germinating seed, it:

A)decreases cell elongation on the lower side of the root.
B)increases cell elongation on the lower side of the root
C)decreases the use of energy by the cells in the root.
D)increases the use of energy by the cells in the root.
E)has no effect on the root (it affects only the developing shoot).

Question 37

What causes the "leaf drop" that occurs in woody plants in preparation for winter dormancy?

A)suppressed auxin production
B)increased chlorophyll development
C)inhibition of gibberellin
D)increased ethylene production
E)opened stomata

Question 38

A species-specific ratio of ________ produced in the apical meristem and ________ produced in the root tips maintains a balance between shoot and root growth.

A)gibberellins; abscisic acid
B)abscisic acid; gibberellins
C)auxins; cytokinins
D)cytokinins; auxins
E)abscisic acid; ethylene

Question 39

When auxin accumulates on the lower side of the shoot of a germinating seed, it:

A)decreases cell elongation on the lower side of the shoot.
B)increases cell elongation on the lower side of the shoot.
C)decreases the use of energy by the cells in the shoot.
D)increases the use of energy by the cells in the shoot.
E)has no effect on the shoot (it affects only the developing root).

Question 40

Elongation of cells in stems is promoted by:

A)ethylene and cytokinins.
B)auxins and gibberellins.
C)enzymes and phytochromes.
D)abscisic acid and ethylene.
E)cytokinins and abscisic acid.

Question 41

What caterpillar saliva-based chemical stimulates a corn plant to release an alarm signal?

A)florigen
B)methyl salicylate
C)salicylic acid
D)volicitin
E)salicin

Question 42

Which of the following is TRUE of the relationship between the phytochrome system and the biological clock of plants?

A)The phytochrome system serves as the biological clock for plants.
B)The phytochrome system manufactures special cells that control the biological clock.
C)The phytochrome system detects light and resets the biological clock.
D)The biological clock detects light and sends the information to the phytochrome system.
E)There is no relationship between the phytochrome system and the biological clock.

Question 43

Plants that flower in the United States only in the early spring (when nights are long)are ________ plants.

A)day-neutral
B)long-day
C)short-day
D)indeterminate-day
E)night-determinate

Question 44

Leaves of the Venus fly trap and other sensitive plants move quickly due to:

A)reduced permeability to potassium ions.
B)muscle-like plant cells called myophytes.
C)hormones that cause plant cell movement.
D)an electrical stimulus and rapid diffusion of ions.

Question 45

Which pigment is responsible for the phototropism responses of plants?

A)chlorophyll
B)phytochrome
C)auxin
D)xanthophyll
E)ethylene

Question 46

The process of aging is called:

A)maturation.
B)elongation.
C)abscission.
D)death.
E)senescence.

Question 47

Willow trees and many other plants produce ________, from which aspirin is made.

A)nicotine
B)acetaminophen
C)acetic acid
D)salicylic acid
E)volantin

Question 48

At night, when little red light is available to the plants in an area:

A)Pr and Pfr are both destroyed.
B)Pr and Pfr are both formed from inactive phytochrome.
C)Pr is converted to Pfr.
D)Pfr is converted to Pr.
E)Pr stimulates flowering.

Question 49

If a storm breaks off the top of a tree, within a year or two, one of the lower branches will grow upward and become the new tree top, while inhibiting other branches from doing the same. This is an example of:

A)the influence of ethylene.
B)the formation of an abscission layer.
C)the presence of cytokinins.
D)apical dominance.
E)phytochrome inhibition.

Question 50

Short-day plants flower only if:

A)the duration of uninterrupted darkness is longer than some species-specific length.
B)their phytochrome-mediated responses are inhibited.
C)abscisic acid is available.
D)they are in the shade.

Question 51

The phytochrome that is active and absorbs far-red light is:

A)Pr.
B)Pfr.
C)Pa.
D)Pe.

Question 52

Plants that flower in Canada in August and in the United States in July (when nights are short)are ________ plants.

A)day-neutral
B)long-day
C)short-day
D)indeterminate-day
E)night-determinate

Question 53

Senescence in plants usually involves:

A)shade from other plants.
B)the formation of an abscission layer.
C)the presence of cytokinins.
D)apical dominance.
E)the development of photosynthetic enzymes.

Question 54

If a plant is living under conditions that limit root growth, shoot growth is:

A)limited as well, due to less cytokinin being produced by the root.
B)limited as well, due to more auxin being produced by the apical meristem.
C)stimulated, due to less cytokinin being produced by the root.
D)stimulated, due to more auxin being produced by the apical meristem.
E)unaffected by the amount of root growth.

Question 55

Some plants under attack by insects can communicate this information to other parts of the same plant and to nearby plants via:

A)vibrations in their roots.
B)the release of chemicals into their roots.
C)the release of chemicals into the air.
D)low-frequency sound waves.

Question 56

The phytochrome Pr:

A)is very unstable.
B)is the active form of Pfr.
C)appears blue in solution.
D)absorbs far-red light.

Question 57

What happens to phytochromes after several days of dark, rainy weather?

A)Pr and Pfr are both destroyed.
B)Pr and Pfr are both formed from inactive phytochrome.
C)Pr is converted to Pfr.
D)Pfr is converted to Pr.
E)Pr stimulates flowering.

Question 58

A new type of strawberry plant produces fruit in the late spring, throughout the summer, and into the fall. It is a(n)________ plant.

A)day-neutral
B)long-day
C)short-day
D)indeterminate-day
E)night-determinate

Question 59

________ plants bloom only when the duration of uninterrupted darkness is shorter than a critical length.

A)Long-day
B)Short-day
C)Neutral-day
D)Phytochrome system
E)Gibberellin-regulated

Question 60

Which environmental factor is most significant for flowering?

A)day length
B)temperature
C)water availability
D)nitrogen availability
E)light intensity

Question 61

An insect that twice touches a Venus fly trap hair changes a(n)________ stimulus into a(n)________ signal.

A)electrical; chemical
B)touch; electrical
C)osmotic; mechanical
D)mechanical; touch

Question 62

As a leaf or fruit ages and prepares to fall from a tree, what type of layer does it form?

Question 63

The only plant hormone that is a gas is cytokinin. True or False?

Question 64

Cytokinins cause most of their responses in plants by stimulating cell ________.

Question 65

Plants are able to measure the length of the night using the ________ system.

Question 66

Why can flowers be brought "into bloom" out of season by changing the duration of light and darkness?

Question 67

What kinds of hormonal changes occur as trees prepare for winter dormancy?

Question 68

Corn plants release chemicals that attract a parasitic wasp. The wasp, in turn, protects the corn plants from destruction by:

A)caterpillars.
B)root worms.
C)other wasps.
D)too dry soils.
E)stinging bees.

Question 69

Venus flytraps catch insects in order to supplement their input of:

A)meat.
B)magnesium.
C)nitrogen.
D)phosphorus.
E)potassium.

Question 70

If a coleus plant that has become tall and spindly, what can you do to encourage it to develop lateral branches, so that it becomes bushier?

Question 71

How do auxin and cytokinin interact to affect the shape and growth of a plant?

Question 72

In the late winter, as seeds prepare to germinate, the levels of ________ in seeds should be declining as the levels of ________ are increasing.

Question 73

Shoots grow up and roots grow down due to thigmotropism. True or False?

Question 74

Defend this statement: Plants are just as capable of responding to their environment as are animals.

Question 75

An old gardening folk tradition uses a "tea" made by soaking the stem tips of willows in water overnight and then using the tea to water cuttings. This is supposed to encourage root formation. Does it work? Why?

Question 76

People should not "torment" their Venus flytrap plant with toothpicks or other indigestible objects (to show off its ability to close its trap)because the plant uses up much of its supply of ________ every time the trap closes.

Question 77

In seeds from northern areas, what plant hormone often needs to be removed to get them to germinate, and how can this be done?

Question 78

When a peach blossom is pollinated, auxin and/or ________ stimulates the development of fruit from the ovary.

Question 79

Auxins are used in rooting powders to encourage the formation of well-branched roots. True or False?

Question 80

Radish plants under insect attack:

A)produce the defensive toxin nicotine.
B)produce bitter chemicals and grow spines on their leaves.
C)rapidly fold their petioles together.
D)release salicin, which is converted to salicylic acid within the insect.