Bio 3 Chapter 46

What is the name of the group of chemicals produced by plant and animal cells that have a specific effect on other cells in that animal or plant?

hormones

antibodies

vitamins

proteins

hormones

Hormones can be transported in blood vessels in animals, but how are they transported in plants?

apical meristem

petiole

phloem and xylem

periderm

stomata

phloem and xylem

Which of the following is a plant hormone that inhibits growth of lateral buds?

abscisic acid

auxin

cytokinin

gibberellins

ethylene

auxin

You had to leave a dozen young plants in a greenhouse at the University over the summer. For water, you set up an automatic watering system to activate once a week to deliver what you thought would be enough water to maintain the plants. You returned to the greenhouse in the fall and found the plants to be about the same size as you left them and with no flowers or seeds but with extensive root growth. You suspected that they did not receive enough water over the summer and were responding to the dry conditions. To confirm your suspicions, you asked a botany professor what might have happened to the plants in this unfavorable, dry environment. The professor responded with which of the following?

"The lack of water caused high levels of auxins to be produced in the shoots."

"The plants had plenty of water so they produced an excess of gibberellins."

"Environmental stimuli caused excess cytokinin to be produced."

"The dry, thus unfavorable, conditions prompted abscisic acid activity and a modified state of dormancy."

"The dry, thus unfavorable, conditions prompted abscisic acid activity and a modified state of dormancy."

• Abscisic acid is synthesized in tissues throughout the plant body and helps plants to withstand unfavorable environmental conditions. Abscisic acid promotes root growth and inhibits stem growth under dry conditions.

The plant hormone cytokinin inhibits the formation of branches in roots. What does it do in shoots?

It promotes formation of branches

It "opens up" both xylem and phloem.

It causes leaf abscission.

It causes elongation in shoots.

It promotes formation of branches

Plant physiologists recently identified a hormone in plants that is able to control the timing of flowering. What is the name of the hormone?

florigen

cytokinin

auxin

ethylene

florigen

“Florigen is produced in response to environmental cues, primarily to day length.”

What is the plant hormone that stimulates ripening in some fruits and other things as well?

cytokinin

abscisic acid

ethylene

auxin

gibberellin

ethylene

Which of the following statements is true about the effects of hormones on plant life cycles?

Hormones control nearly all aspects of the plant life cycle by influencing gene activity.

The life cycle of a plant is controlled only by environmental stimuli.

The plant's life cycle is solely the responsibility of enzymes.

The plant's life cycle does not require an interaction with the environment.

Hormones control nearly all aspects of the plant life cycle by influencing gene activity.

“Hormones, which are released in response to environmental cues, provide an important link between the plant's genetic information and its environment.”

How does abscisic acid enforce seed dormancy?

It affects the temperature at which the seed will germinate.

It prevents the embryo from producing gibberellin.

It slows metabolism of the embryo.

It increases metabolism within the embryo.

It slows metabolism of the embryo.

“Correct. The amount of abscisic acid in the seed must be reduced before the seed can germinate.”

What is the most important factor that determines the success or failure of new seedlings?

genetic alterations that make the plant better adapted to the environment

the presence of other members of the same species in the general area of the new seedling

the size of the seed

the timing of seed germination

the timing of seed germination

“Appropriate timing ensures that new seedlings will have adequate water and appropriate temperatures to thrive.”

What is the role of gibberellin in seed germination?

Gibberellin is responsible for initiating photosynthesis.

Gibberellin, produced by the embryo, stimulates germination.

Gibberellin strengthens root caps.

It reduces the amount of water normally required for germination.

Gibberellin, produced by the embryo, stimulates germination.

“The enzymes that are produced break down starch reserves in the endosperm for the energy needed for germination.”

How does a hard rainfall stimulate desert flowering seeds to germinate in large numbers?

Rainfall lowers desert temperature.

It increases the production of abscisic acid in the embryo.

The hard rain washes abscisic acid away, allowing seeds to germinate.

Rainfall decreases production of gibberellin.

The hard rain washes abscisic acid away, allowing seeds to germinate.

“The resulting seedlings must grow and reproduce rapidly before the desert dries out.”

Plants are able to grow toward or away from light, a characteristic called __________.

thigmotropism

phototropism

gravitropism

germination

phototropism

“It is important for plants to grow toward the sun to maximize the energy they capture for photosynthesis.”

What is the name of the hormone that helps shoots grow toward light?

abscisic acid

endosperm

auxin

gibberellin

auxin

“Hormones are involved in many plant responses to environmental stimuli. Auxin accumulates in the side of the shoot away from the light, causing this side to elongate and bending the shoot toward the light.”

What specialized starch-filled structures, found in certain cells in the shoot and root cap, play a role in gravitropism?

cytokinin

statoliths

auxin

apical meristem

statoliths

“Statoliths always settle to the lower part of the cell and result in auxin accumulation, which causes the root to grow downward into the soil.”

Some plants wrap tendrils around structures for support. What is this plant response called?

gravitropism

phototropism

thigmotropism

elongation

thigmotropism

“Thigmotropic plants move or grow in response to touch”

Which of the following best describes the phenomenon called apical dominance?

Lateral buds close to the shoot tip are inhibited by auxin from developing into branches, unlike lateral buds further from the shoot, where cytokinin stimulates branching.

Apical dominance is the result of a plant experiencing progressive increases in day length.

Higher concentrations of abscisic acid in the shoot tip prevent lateral growth of buds whereas higher concentrations of cytokinins lower in the shoot encourage lateral bud growth.

Lateral buds close to the shoot tip are inhibited by cytokinin whereas lower buds are stimulated by auxin.

Lateral buds close to the shoot tip are inhibited by auxin from developing into branches, unlike lateral buds further from the shoot, where cytokinin stimulates branching.

“The balance between auxin and cytokinin is the key to branching.”

Plants in temperate climates use environmental cues to determine the seasons. Which environmental cue appears to be the most reliable?

phase of the moon

temperature

water availability

day length

soil texture

day length “Although day length varies in the course of a year, it is consistent from year to year.”

How could you make it profitable to pick green bananas in Central America and ship them to sell as ripe bananas in North America?

Treat them with the hormone abscisic acid.

Use enzymes to soften bananas, a characteristic of ripeness.

Ripen them with the hormone ethylene before they arrive in food stores.

Extend the time it takes to ship them.

Ripen them with the hormone ethylene before they arrive in food stores.

“Many fruits, including tomatoes, can be ripened with ethylene.”

When does the abscission layer become important to the plant?

during expression of florigen genes

during seed germination

during seed and fruit development

when the plant undergoes senescence

when the plant undergoes senescence

“This allows the leaves and fruit to drop at the appropriate time.”

Which of the following is a true statement?

Some plants produce the hormone salicylic acid to defend infecting microorganisms.

Leaf damage from insects can cause the plant to respond by making itself distasteful.

Unlike animals, an immune response cannot be found in plants.

Genetics is not involved in a plant's ability to protect itself.

Leaf damage from insects can cause the plant to respond by making itself distasteful.

Several chemicals synthesized by plants have been purified to treat human ailments. One such chemical is made by willow trees to protect themselves against herbivores, and when ingested by humans, reduces pain. What is it?

nicotine

salicin

steroids

penicillin

salicin

“Salicin is converted to salicylic acid in the human stomach, but salicin is better tolerated if converted and marketed as acetylsalicylic acid (aspirin).”

How are carnivorous plants able to survive in nitrogen-poor marshes?

Nitrogen is supplied by other plants growing in the same general area.

Nitrogen is not required as a macronutrient.

They get nitrogen from insects they trap and eat.

They are able to capture nitrogen from the atmosphere.

They get nitrogen from insects they trap and eat.

“Other plants cannot compete with them in this environment.”

An example of a plant that is sensitive to touch is __________.

Mimosa

strawberry

radish

ragweed

oak

Mimosa

The hormone auxin exerts a diverse assortment of effects in different __________ cells.

elongating

root

lateral

target

target

How a plant cell responds to a hormone depends on the

concentration of the hormone.

cell that secretes the hormone.

presence of other plant cells nearby.

amount of available sunlight.

"shelf life" of the hormone.

concentration of the hormone.

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

Auxins are present in low concentrations in the bag because sunlight stimulates the production of this hormone.

Abscisic acid, produced by the fruit, is trapped in the bag.

Ethylene, produced by the fruit, is trapped in the bag.

Cytokinins are present in low concentrations in the bag because sunlight stimulates the production of this hormone.

The bag holds in more moisture.

Ethylene, produced by the fruit, is trapped in the bag.

Pea plant tendrils wrapping around a string demonstrate

phototropism.

lumitropism.

gravitropism.

amylotropism.

thigmotropism.

thigmotropism

Tomatoes that are planted upside down still grow upright, displaying

phototropism.

lumitropism.

gravitropism.

amylotropism.

thigmotropism.

gravitropism

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

produced in large amounts.

made from cell proteins.

capable of stimulating differentiated cells to form meristem tissue.

needed by the plant as a major source of energy.

formed in one part of the plant but has an effect in a different part.

formed in one part of the plant but has an effect in a different part.

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

auxin.

cytokinin.

ethylene gas.

gibberellin.

florigen.

auxin

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

ethylene

cytokinin

florigen

gibberellin

auxin

gibberellin

Roots grow downward and shoots grow upward due to

cytokinin.

ethylene.

abscisic acid.

auxin.

gibberellin.

auxin

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

Ethylene

Cytokinin

Abscisic acid

Gibberellin

Auxin

Ethylene

Which of these hormones helps plants tolerate drought and cold?

Auxin

Abscisic acid

Cytokinin

Ethylene

Gibberellin

Abscisic acid

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

gibberellin.

abscisic acid.

cytokinin.

auxin.

ethylene.

cytokinin

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

auxins.

ethylenes.

florigens.

cytokinins.

abscisic acids.

florigens

Venus flytraps catch insects in order to supplement their input of

magnesium.

meat.

potassium.

nitrogen.

phosphorus.

nitrogen

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

True

False

False, it’s ethylene

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

The lack of nitrogen in bogs selects for the carnivorous plant lifestyle of ingesting and digesting animals for nitrogen.

Bogs are naturally high in nitrogen, which favors the carnivorous plant lifestyle.

Bogs contain rich populations of nitrogen-fixing bacteria, which provide nitrogen to the plants.

Bogs contain many soil-based proteins, which are a good source of nitrogen.

The lack of nitrogen in bogs selects for the carnivorous plant lifestyle of ingesting and digesting animals for nitrogen.

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?

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.

No; sunlight penetrates soil to the depth of seeds and shoots grow toward the sunlight.

No; auxins in the shoots cause curvature away from gravity.

Yes; after seeds are planted, water and settling of the soil may cause them to shift in their orientation.

No; gibberellins and abscisic acid, in balanced concentrations, cause shoots to grow away from gravity.

No; auxins in the shoots cause curvature away from gravity.

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

The overripe apple makes ethylene gas, which can cause the good apples to ripen more quickly than usual.

Gibberellins help preserve the good apples.

Ethylene production in the good apples is inhibited by the lack of ethylene production in the overripe apple.

The production of cytokinins is inhibited in the remaining good apples.

Chemicals in the overripe apple stimulate the conversion of sugar to starch in the good apples.

The overripe apple makes ethylene gas, which can cause the good apples to ripen more quickly than usual.

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

auxin.

florigen.

abscisic acid.

cytokinin.

ethylene.

florigen

You see a plant that is growing straight up even though it has a strong light source on one side only. How can you explain this?

Ethylene is not being synthesized in this plant.

Auxin is not being synthesized in this plant.

Xylem is not being synthesized in this plant.

Gibberellins are not being synthesized in this plant.

Auxin is not being synthesized in this plant.

What is produced by the pressure of newly emerging roots and shoots against the soil that causes the roots and shoots to become thicker, stronger, and better able to force their way through the soil?

florigen

thigmotropism

gibberellins

porous gelatin

ethylene

ethylene

“Pressure experienced by the root induces ethylene production that slows elongation and encourages a tougher root.”

What term describes the influence of auxin in the growing tip of a plant?

senescence

day-neutral

abscission

apical dominance

apical dominance

“Auxin concentration decreases as it diffuses down the stem, so more branching occurs further from the shoot apical meristem.”

Plants can detect light and darkness using a photopigment called __________.

red light

phytochrome

florigen

auxin

phytochrome

“The pigment allows plants to measure light-dark cycles and respond appropriately.”

Gravitropism is a plant's

directional response to gravity.

apical dominance.

ability to form an abscission layer, so that the fruits and leaves fall from the plant.

ability to grow only upward.

response to stress-inducing situations.

directional response to gravity.

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

Abscisic acid; ethylene

Auxin; cytokinin

Abscisic acid; gibberellin

Cytokinin; auxin

Gibberellin; abscisic acid

Abscisic acid; gibberellin

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

abscisic acid; gibberellins

auxins; cytokinins

abscisic acid; ethylene

cytokinins; auxins

gibberellins; abscisic acid

auxins; cytokinins

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

absorbs cytokinin.

makes auxin.

produces ethylene gas.

releases heat.

forms digestive enzymes.

produces ethylene gas.

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

removing the apical meristems results in less auxin, which results in more lateral branch growth.

removing the apical meristems makes more auxin, which stimulates lateral branch buds to grow.

removing the apical meristems makes less ethylene, which stimulates lateral branches to grow.

removing the lateral buds results in apical dominance under the influence of cytokinins.

removing the apical meristems results in less auxin, which results in more lateral branch growth

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

abscisic acid.

gibberellin.

ethylene.

auxin.

auxin

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

Treat them with abscisic acid.

Treat them with gibberellin.

Treat them with auxin.

Put them in direct sunlight.

Boil them.

Treat them with gibberellin.

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?

Abscisic acid

Auxin

Gibberellin

Ethylene

Cytokinin

Abscisic acid

Auxin

promotes phototropism.

stimulates flowering.

inhibits stem elongation.

promotes cell division.

causes the development of an abscission layer.

promotes phototropism

Elongation of cells in stems is promoted by

enzymes and phytochromes.

auxins and gibberellins.

abscisic acid and ethylene.

ethylene and cytokinins.

cytokinins and abscisic acid.

auxins and gibberellins.

Abscisic acid enforces dormancy of seeds by

binding to the molecule ATP.

preventing the development of the embryo and completion of the lifecycle.

preventing endosperm development.

waterproofing the seed coat.

activating gibberellin.

preventing the development of the embryo and completion of the lifecycle.

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

Increased ethylene production

Increased chlorophyll development

Opened stomata

Inhibition of gibberellin

Suppressed auxin production

Increased ethylene production

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

Ethylene

Auxin

Cytokinin

Abscisic acid

Gibberellin

Abscisic acid

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

has no effect on the shoot; it affects only the developing root.

decreases the use of energy by the cells in the shoot.

increases cell elongation on the lower side of the shoot.

decreases cell elongation on the lower side of the shoot.

increases the use of energy by the cells in the shoot.

increases cell elongation on the lower side of the shoot.

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

decreases cell elongation on the lower side of the root.

has no effect on the root; it affects only the developing shoot.

decreases the use of energy by the cells in the root.

increases the use of energy by the cells in the root.

increases cell elongation on the lower side of the root

decreases cell elongation on the lower side of the root.

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

abscisic acid and cytokinins.

ethylene and abscisic acid.

gibberellins and abscisic acid.

cytokinins and ethylene.

auxins and cytokinins.

auxins and cytokinins

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

Cytokinin

Gibberellin

Abscisic acid

Ethylene

Auxin

Auxin

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

produce gibberellins.

are most exposed to the light.

are the most affected by gravity.

are shaded by the apical bud and the top of the tree.

receive the most auxin from the apical bud.

receive the most auxin from the apical bud.

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

are shaded by the top of the tree.

produce gibberellins.

receive the most cytokinins from the roots.

are the most affected by gravity.

receive the least light.

receive the most cytokinins from the roots.

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

stimulated, due to more auxin being produced by the apical meristem.

limited as well, due to more auxin being produced by the apical meristem.

unaffected by the amount of root growth.

stimulated, due to less cytokinin being produced by the root.

limited as well, due to less cytokinin being produced by the root.

limited as well, due to less cytokinin being produced by the root.

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

Short-day

Long-day

Neutral-day

Phytochrome-system

Gibberellin-regulated

Long-day

Which environmental factor is most significant for flowering?

Day length

Nitrogen availability

Light intensity

Water availability

Temperature

Day length

Short-day plants flower only if

abscisic acid is available.

their phytochrome-mediated responses are inhibited.

they are in the shade.

the duration of uninterrupted darkness is longer than some species-specific length.

the duration of uninterrupted darkness is longer than some species-specific length

Which pigment is responsible for the phototropism responses of plants?

Auxin

Chlorophyll

Ethylene

Phytochrome

Xanthophyll

Phytochrome

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

The phytochrome system serves as the biological clock for plants.

The phytochrome system detects light and resets the biological clock.

The phytochrome system manufactures special cells that control the biological clock.

The biological clock detects light and sends the information to the phytochrome system.

There is no relationship between the phytochrome system and the biological clock.

The phytochrome system detects light and resets the biological clock

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

Pr is converted to Pfr.

Pr and Pfr are both destroyed.

Pr stimulates flowering.

Pr and Pfr are both formed from inactive phytochrome.

Pfr is converted to Pr.

Pfr is converted to Pr.

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

Pe.

Pfr.

Pr.

Pa.

Pfr

The phytochrome P_r

is inactive and absorbs red light.

absorbs far-red light.

is very unstable.

is the active form of Pfr.

is inactive and absorbs red light.

The process of aging is called

senescence.

death.

elongation.

maturation.

abscission.

senescence

Senescence in plants usually involves

shade from other plants.

the formation of an abscission layer.

the development of photosynthetic enzymes.

apical dominance.

the presence of cytokinins.

the formation of an abscission layer.

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

the formation of an abscission layer.

the influence of ethylene.

apical dominance.

phytochrome inhibition.

the presence of cytokinins.

apical dominance

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

Pfr spontaneously reverts to Pr..

Pr absorbs darkness and converts to Pfr.

Pr and Pfr are both formed from inactive phytochrome.

Pr stimulates flowering.

Pr and Pfr become unstable and both are destroyed.

Pfr spontaneously reverts to Pr.

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

day-neutral

long-day

short-day

indeterminate-day

night-determinate

short-day

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

day-neutral

long-day

short-day

indeterminate-day

night-determinate

day-neutral

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

True

False

false

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

True

False

True

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?

Nothing will happen; growth and development will continue as normal.

The plants won't flower that season.

The plants will be delayed in flowering.

The plants are tricked into flowering earlier than usual.

The plants are tricked into flowering earlier than usual.

Ethylene

stimulates seed germination.

promotes gravitropism.

causes phototropism.

prevents leaf senescence.

promotes leaf and fruit drop.

promotes leaf and fruit drop.

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

day-neutral

long-day

short-day

indeterminate-day

night-determinate

long-day

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

an electrical stimulus and rapid diffusion of ions out of motor cells.

reduced permeability to potassium ions.

muscle-like plant cells called myophytes.

hormones that cause plant cell movement.

an electrical stimulus and rapid diffusion of ions out of motor cells.

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

vibrations in their roots.

the release of chemicals into their roots.

the release of chemicals into the air.

low-frequency sound waves.

the release of chemicals into the air.

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

acetaminophen

salicylic acid

volantin

nicotine

acetic acid

salicylic acid

Radish plants under insect attack

rapidly fold their petioles together.

produce the defensive toxin nicotine.

release salicin, which is converted to salicylic acid within the insect.

produce bitter chemicals and grow spines on their leaves.

produce bitter chemicals and grow spines on their leaves.

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

root worms.

stinging bees.

too dry soils.

other wasps.

caterpillars.

caterpillars

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

Salicin

Volicitin

Methyl salicylate

Salicylic acid

Florigen

Volicitin

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

Thigmotropism is activated, and it kills the insect.

An electrical shock kills the insect.

The sundew's leaves snap shut and their spiked edges mesh, trapping the insect.

The plant secretes a cocktail of digestive enzymes that rapidly breaks down the insect's body.

The plant secretes a cocktail of digestive enzymes that rapidly breaks down the insect's body.

Evergreen trees lose their leaves _____.    

in the summer

steadily all year

in the spring

every winter

every fall

steadily all year

The breakdown of chlorophyll reveals the _____ pigments of a leaf.    

anthocyanin

carotenoid

phycoerythrin

xanthophylls

melanin

carotenoid

The formation of the abscission layer cuts off transport of substances to and from the leaf. As the concentration of sugar trapped within a leaf increases, _____ pigments are produced.    

anthocyanin

xanthophyll

carotenoid

melanin

phycoerythrin

anthocyanin

The protective layer that forms between the abscission layer and the stem consists of _____.    

irregularly shaped cells with very thick, lignified secondary walls

a layer of green palisade cells

mycorrhizae

densely colored cells filled with a waxy layer

weak, colorless, thin-walled cells

densely colored cells filled with a waxy layer    

After leaf abscission, growth will resume from the _____.    

palisade layer

axillary bud

abscission layer

petiole

protective layer

axillary bud

_____ trees lose their leaves in preparation for winter.    

Spruce

Deciduous

Pine

Fir

Conifer

deciduous