Deck 46: Plant Responses to the Environment

Question 1

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

A) No; gibberellins and abscisic acid, in balanced concentrations, cause shoots to grow away from gravity.
B) No; auxins in the shoots cause curvature away from gravity.
C) Yes; after seeds are planted, water and settling of the soil may cause them to shift in their orientation.
D) Yes; if the seed was oriented so that the embryonic shoot pointed down, it would grow in that direction because sunlight doesnʹt reach it.
E) No; sunlight penetrates soil to the depth of seeds and shoots grow toward the sunlight.

Answer 1

B

Question 2

Which of these hormones helps plants tolerate drought and cold?

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

Answer 2

D

Question 3

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) The bag holds in more moisture.
C) Abscisic acid, produced by the fruit, is trapped in the bag.
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.

Answer 3

A

Question 4

A plantʹs tendency to grow toward a source of light is called

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

Question 5

Gravitropism is a plantʹs

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

Question 6

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

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

Question 7

The hormone__________ was named after the fungus that causes ?foolish seedling? disease in rice.

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

Question 8

__________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) Auxin; cytokinin
C) Cytokinin; auxin
D) Abscisic acid; ethylene
E) Abscisic acid; gibberellin

Question 9

A botanist who wants to stimulate flower formation in response to light cues could treat the plants with

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

Question 10

How a plant cell responds to a hormone depends on the

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

Question 11

__________triggers the formation of weak-celled abscission layers in leaves and fruits, allowing them to drop off at appropriate times during the year.

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

Question 12

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

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

Question 13

Seed germination is stimulated by

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

Question 14

How is the carnivorous plant lifestyle suited for an existence in bogs?

A) Bogs are naturally high in nitrogen, which favors the carnivorous plant lifestyle.
B) Bogs contain many soil-based proteins, which are a good source of nitrogen.
C) Bogs contain rich populations of nitrogen-fixing bacteria, which provide nitrogen to the plants.
D) The lack of nitrogen in bogs selects for the carnivorous plant lifestyle of ingesting and digesting animals for nitrogen.

Question 15

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

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

Question 16

Roots grow downward and shoots grow upward due to

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

Question 17

In 2007, research confirmed the existence of hormones that control the timing of flowering. These hormones are called

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

Question 18

Pea plant tendrils wrapping around a string demonstrate

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

Question 19

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

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

Question 20

Tomatoes that are planted upside down still grow upright, displaying

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

Question 21

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

A) increases cell elongation on the lower side of the shoot.
B) decreases the use of energy by the cells in the shoot.
C) decreases cell elongation on the lower side of 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 22

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) decreases the use of energy by the cells in the root.
C) increases cell elongation on the lower side of 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 23

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

Question 24

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

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

Question 25

The two hormones involved in seed germination and seed dormancy are

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

Question 26

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

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

Question 27

Auxin

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

Question 28

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

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

Question 29

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

Question 30

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 abscisic acid.
D) Treat them with auxin.
E) Put them in direct sunlight.

Question 31

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

A) The plants wonʹt flower that season.
B) The plants are tricked into flowering earlier than usual.
C) Nothing will happen; growth and development will continue as normal.
D) The plants will be delayed in flowering.

Question 32

Abscisic acid enforces dormancy of seeds by

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

Question 33

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

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

Question 34

Ethylene

A) stimulates seed germination.
B) promotes gravitropism.
C) causes phototropism.
D) prevents leaf senescence.
E) promotes leaf and fruit drop.

Question 35

What causes the ʺleaf dropʺ that occurs in woody plants in preparation for winter dormancy?

A) Opened stomata
B) Suppressed auxin production
C) Increased chlorophyll development
D) Increased ethylene production
E) Inhibition of gibberellin

Question 36

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

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

Question 37

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

Question 38

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

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

Question 39

Elongation of cells in stems is promoted by

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

Question 40

__________induces dormancy in seeds and buds and causes stomata to close.

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

Question 41

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

Question 42

The phytochrome Pr

A) is inactive and absorbs red light.
B) is the active form of Pfr.
C) is very unstable.
D) absorbs far-red light.

Question 43

Senescence in plants usually involves

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

Question 44

Plants that flower 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 45

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 46

Leaves of the Venus flytrap and other sensitive plants move quickly due to

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

Question 47

Short-day plants flower only if

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

Question 48

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

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

Question 49

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

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

Question 50

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

A) The biological clock detects light and sends the information to the phytochrome system.
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 phytochrome system serves as the biological clock for plants.
E) There is no relationship between the phytochrome system and the biological clock.

Question 51

The process of aging is called

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

Question 52

Which pigment is responsible for the phototropism responses of plants?

A) Ethylene
B) Phytochrome
C) Chlorophyll
D) Auxin
E) Xanthophyll

Question 53

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 54

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

A) Salicin
B) Salicylic acid
C) Volicitin
D) Methyl salicylate
E) Florigen

Question 55

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

A) Pr and Pfr become unstable and both are destroyed.
B) Pr absorbs darkness and converts to Pfr.
C) Pr and Pfr are both formed from inactive phytochrome.
D) Pr stimulates flowering.
E) Pfr spontaneously reverts to Pr.

Question 56

Which environmental factor is most significant for flowering?

A) Water availability
B) Light intensity
C) Temperature
D) Nitrogen availability
E) Day length

Question 57

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

Question 58

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

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

Question 59

At night, when little red light is available to the plants in an area, what occurs?

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

Question 60

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

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

Question 61

Radish plants under insect attack

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

Question 62

The only plant hormone that is a gas is cytokinin.

Question 63

Cytokinins cause most of their responses in plants by stimulating cell__________ .

Question 64

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

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

Question 65

Plants, as prey, canʹt run away from their predators, but they can defend themselves. Is the predatory nature of Venus flytraps a defense mechanism, or does it serve some other purpose?

Question 66

Ripening fruits are attached firmly to their trees, but once they are mature, the trees must release them. How does this happen?

Question 67

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

Question 68

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

Question 69

Why can flowers be brought ʺinto bloomʺ out of season by changing the duration of light and darkness?

Question 70

Venus flytraps catch insects in order to supplement their input of

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

Question 71

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

Question 72

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

Question 73

A Native American tradition uses a ʺteaʺ made by soaking willow bark in water as a pain-reliever. Does it work? Why?

Question 74

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

Question 75

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

Question 76

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

Question 77

Plants are able to measure the length of the night using the __________system.

Question 78

Vibrations from an insect trapped inside a carnivorous sundew and thrashing around to escape stimulate the sundewʹs response. What happens next?

A) Thigmotropism is activated, and it kills the insect.
B) The plant secretes a cocktail of digestive enzymes that rapidly breaks down the insectʹs body.
C) The sundewʹs leaves snap shut and their spiked edges mesh, trapping the insect.
D) An electrical shock kills the insect.

Question 79

Shoots grow up and roots grow down due to thigmotropism.

Question 80

In the late winter, as seeds prepare to germinate, the levels of __________in seeds should be declining as the levels of __________are increasing.