Deck 36: Regulation of Plant Growth

Question 1

A researcher studying a seedling can determine its stage of development according to the molecular phenomena that are occurring.If DNA synthesis is observed, the seedling is at the stage at which

A) gibberellins are secreted by the embryo.
B) the embryonic root, or radicle, begins to grow.
C) imbibition takes place.
D) the endosperm starts metabolizing starches, proteins, and lipids.
E) the aleurone layer assembles enzymes, proteases, and ribonucleases.

Answer 1

B

Question 2

Refer to the diagram below showing cereal grain germination. Wheat grains are processed to produce flour before germination occurs.Which part of the seed is used to mill white flour (which is mostly starch)?

A) A
B) B
C) C
D) D
E) E

Answer 2

D

Question 3

Which answer choice is not an adaptive advantage of seed dormancy?

A) Increased likelihood of germination at a favorable time
B) Increased likelihood of germination in the right place
C) Decreased likelihood of competition
D) Increased likelihood of dispersal
E) Increased likelihood that environmental conditions will be different from those to which the parent plant was adapted

Answer 3

E

Question 4

Refer to the diagram below showing cereal grain germination. Which layer of the grain produces hydrolytic enzymes during germination?

A) A
B) B
C) C
D) D
E) E

Question 5

A team of molecular biology researchers is trying to increase the value of agricultural seeds for livestock feed.To increase the store of metabolically useful energy in the seeds, the researchers should focus on increasing which of the following macromolecules?

A) DNA and nucleic acids
B) Lipids and starches
C) Germination inhibitors
D) Proteins and amino acids
E) Cellulose and lignin

Question 6

Seeds of a plant that is native to Mexico are released in mid-spring just as their native habitat is drying out and becoming unfavorably hot.They are quiescent after they are released.This example demonstrates that seed quiescence usually helps ensure that

A) the embryo is mature.
B) germination occurs at a favorable time.
C) seeds germinate near the parent plant.
D) levels of abscisic acid are high enough for seed germination.
E) many seeds are ready to germinate.

Question 7

In order to respond to environmental stimuli, plants employ sequences of biochemical reactions called

A) signal transduction pathways.
B) cellular responses.
C) regulation.
D) cell elongation.
E) abscission.

Question 8

A scientist receives a seed sample from a plant growing in an unknown location and discovers that prolonged cold treatment is needed to break seed dormancy.This suggests that in the native habitat of the plant, the colder part of the year

A) occurs right before the best growing season.
B) is favorable for growth.
C) lasts for several months.
D) is brief.
E) is the best source of far-red light.

Question 9

If you were conducting a study to determine how seeds from various habitats break dormancy, which of the following would be the least useful experimental variable?

A) Fire
B) Low oxygen levels
C) Cycles of freezing and thawing
D) Washing away inhibitor molecules
E) Variations in soil microorganisms

Question 10

Which of the following represents the correct order of the stages of seed germination and subsequent events?

A) Imbibition $\rightarrow$ RNA synthesis $\rightarrow$ cell division $\rightarrow$ starch degradation
B) Imbibition $\rightarrow$ starch degradation $\rightarrow$ cell division $\rightarrow$ RNA synthesis
C) Starch degradation $\rightarrow$ RNA synthesis $\rightarrow$ cell division $\rightarrow$ imbibition
D) Starch degradation $\rightarrow$ RNA synthesis $\rightarrow$ imbibition $\rightarrow$ cell division
E) Imbibition $\rightarrow$ RNA synthesis $\rightarrow$ starch degradation $\rightarrow$ cell division

Question 11

A scientist is studying seeds from a species of sundew native to Western Australia.These seeds need to be treated with smoke before they can imbibe and germinate.This suggests that _______ for the seeds to germinate.

A) seed dormancy must be broken
B) the radicle must emerge from the seed
C) water must be excluded
D) oxygen must be excluded
E) cell division must increase greatly

Question 12

The prephotosynthetic seedling must survive using resources from the _______ or the _______.

A) cotyledons; endosperm
B) radicle; hypocotyl
C) foliage leaf; epicotyl
D) seed coat; coleoptile
E) apical hook; secondary roots

Question 13

It was discovered recently that both auxin and gibberellins have specific protein receptors that, when bound by hormones,

A) inactivate certain gene repressors in the nucleus.
B) activate certain gene repressors in the nucleus.
C) initiate a protein kinase cascade.
D) activate proton pumps in the plasma membrane.
E) acidify the cell wall.

Question 14

You are given a sample of seeds to analyze and are told that the germination process may have begun.If this is the case, the seeds will

A) be dehydrated.
B) have been placed in the ground and then removed for analysis.
C) have imbibed water.
D) have high levels of abscisic acid.
E) be dormant.

Question 15

All of the following may serve to break dormancy and initiate seed germination except

A) abrasion.
B) fire.
C) exposure to water.
D) treatment with abscisic acid.
E) treatment with gibberellins.

Question 16

Which of the following steps is initially most crucial for the survival of the growing seedling that germinated an inch underground?

A) Production of chlorophyll
B) Rapid elongation of the shoot
C) Breaking of dormancy
D) Rapid start of photosynthesis
E) Expansion of cotyledons

Question 17

All of the following are plant hormones except

A) abscisic acid.
B) brassinosteroids.
C) cytokinins.
D) gibberellins.
E) phytochrome.

Question 18

Which of the following does not increase during the initial stages of seed germination?

A) Cell size
B) Respiration
C) RNA synthesis
D) Cell division rate
E) Protein synthesis

Question 19

Which of the following does not occur during the earliest stages of germination?

A) Intake of water
B) Activation of enzymes
C) Cell division
D) Increase in cellular respiration
E) Mobilization of food reserves

Question 20

A biology class studying plant development is observing the germination of orange seeds.What structure are they most likely to observe emerging from the seed coat?

A) Hypocotyl
B) Epicotyl
C) Coleoptile
D) Cotyledon
E) Radicle

Question 21

A new variety of geranium is found that, unlike other members of the genus, grows for a year as a squat, short plant, and then bolts to produce a tall stem with many flowers.What hormone is most likely produced in large amounts just before bolting?

A) Auxin
B) Abscisic acid
C) Gibberellins
D) Ethylene
E) Cytokinins

Question 22

In promoting normal germination (and also in brewing, when production of sugars for alcoholic fermentation is desired), gibberellins

A) absorb light.
B) cause stem elongation.
C) mobilize stored foods.
D) take up water.
E) direct the shoot upward.

Question 23

The increasing popularity of small home vegetable gardens over the last century has increased the need for smaller, dwarf cultivars of various vegetables such as peas and tomatoes.In general, these dwarfs produce less _______ than their wild-type counterparts.

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

Question 24

Plant primary roots typically grow into the ground by responding to the directional signal of gravity.If you wanted to identify a plant that had a mutation in its gravity signal transduction pathway, which of the following methods would be most useful?

A) Growing a batch of seeds in zero-gravity conditions and then collecting any seedlings with primary roots that are growing in different directions
B) Treating a batch of seeds with a mutagen, placing each germinating seed on the soil with the primary roots emerging in a different direction, and collecting any plants with primary roots that grow into the soil
C) Treating a batch of seeds with a mutagen, growing them alongside wild-type seeds, and collecting any seedlings with primary roots growing longer than the wild-type roots
D) Growing a batch of seeds in zero-gravity conditions and then collecting any seedlings with primary roots that are growing toward the ground
E) Treating a batch of seeds with a mutagen, growing them alongside wild-type seeds, and collecting any seedlings with primary roots growing in a direction that is different from that of the wild-type roots

Question 25

Treatment of some plants with gibberellins or auxin causes parthenocarpy, which is the formation of

A) flowers that lack embryos.
B) seeds that lack embryos.
C) fruit with only one seed instead of many.
D) fruit without fertilization.
E) an embryo without fertilization.

Question 26

Whereas gibberellins promote seed germination, _______ promote(s) dormancy.

A) auxin
B) cytokinins
C) abscisic acid
D) brassinosteroids
E) ethylene

Question 27

Gibberellins were discovered by the biologist Eiichi Kurosawa while he was studying a fungal infection of _______, in which seedlings _______.

A) corn; grow unusually slowly
B) rice; grow into tall, spindly plants
C) wheat; die after germination
D) barley; produce seeds unusually early
E) millet; have a beneficial mutation

Question 28

Beer breweries use gibberellins to ensure consistent germination and liberation of sugars from starch in grain endosperm.Which layer of the grain responds to the applied gibberellins?

A) Mesophyll
B) Cotyledon
C) Aleurone
D) Seed coat
E) Embryo

Question 29

Which of the following statements does not describe the signal transduction pathway initiated by the binding of auxin to its receptor protein?

A) Auxin binds to its receptor protein.
B) The auxin-receptor complex enters the cell.
C) The auxin-receptor complex binds to the repressor and interacts with ubiquitin.
D) The repressor is activated, blocking gene expression.
E) The repressor is broken down, leading to gene expression.

Question 30

Which of the following represents the correct order of events in ethylene signal transduction?

A) Ethylene is produced $\rightarrow$ ethylene binds to its receptor protein $\rightarrow$ cytoplasmic steps are initiated $\rightarrow$ transcription factor is activated
B) Ethylene is produced $\rightarrow$ cytoplasmic steps are initiated $\rightarrow$ transcription factor is activated $\rightarrow$ ethylene binds to its receptor protein
C) Ethylene binds to its receptor protein $\rightarrow$ cytoplasmic steps are initiated $\rightarrow$ transcription factor is activated $\rightarrow$ ethylene is produced
D) Ethylene binds to its receptor protein $\rightarrow$ transcription factor is activated $\rightarrow$ ethylene is produced $\rightarrow$ cytoplasmic steps are initiated
E) Cytoplasmic steps are initiated $\rightarrow$ transcription factor is activated $\rightarrow$ ethylene is produced $\rightarrow$ ethylene binds to its receptor protein

Question 31

The gibberellin signal transduction pathway leads to

A) breakdown of proteins to allow for gene expression.
B) inactivation of growth-stimulating genes.
C) inactivation of proteases.
D) inhibition of the polyubiquitination of repressor proteins.
E) conversion of phytochrome P_r to phytochrome P_fr.

Question 32

Evidence that gibberellins are produced by plants was gathered in studies with dwarf mutant strains of tomato.Work on dwarf peas produced the same results: treatment with gibberellins caused the dwarf plants to _______, while the normal, tall plants _______.

A) grow taller; also grew taller, but only slightly
B) grow taller; were virtually unaffected
C) stop growing immediately; stopped growing after a period of time
D) stop growing; were virtually unaffected
E) die; stopped growing

Question 33

Suppose that seedless raspberries have been discovered in a genetic screen and commercialized.What plant hormone could be added to the developing fruits so they will grow to the normal size of seeded fruits?

A) Cytokinins
B) Nitrous oxide
C) Ethylene
D) Abscisic acid
E) Gibberellins

Question 34

Gibberellins do not have a major effect on

A) shoot growth.
B) fruit development.
C) seed germination.
D) root growth.
E) breaking winter dormancy.

Question 35

A botanist is trying to isolate all of the auxin produced in a bean plant by extracting it from seedlings in a range of developmental stages.Which of the following features of plant hormones must the scientist take into consideration while planning the extraction protocol?

A) They have a single specific role.
B) They affect mainly the cells that produce them.
C) They are species-specific.
D) They are produced in many different parts of the plant.
E) They elicit rapid responses.

Question 36

A botanist is studying a newly discovered plant that is native to Norway.Which of the following would be the earliest indication that gibberellins play the same role in this plant that they play in flowering and reproduction in cabbage?

A) Leaf senescence
B) Elongation of the stem
C) The shape of the flowers
D) The size of the fruit
E) The number of seeds per fruit

Question 37

If you placed an auxin-containing agar block off-center on the cut top surface of a sunflower seedling, you would expect, after a day, to find that the sunflower had

A) grown straight up.
B) grown and bent away from the side with the block.
C) grown and bent toward the side with the block.
D) failed to grow.
E) died.

Question 38

Refer to the figure below.Each photograph shows a dwarf plant with a hormonal deficiency and a normal-sized plant of the same species. Differential action of which two hormones might explain the differing plant sizes in the images?

A) Cytokinins and ethylene
B) Ethylene and gibberellins
C) Auxin and gibberellins
D) Gibberellins and brassinosteroids
E) Cytokinin and abscisic acid

Question 39

A botanist compares a wild-type plant to two different mutant plants of the same species.One of the mutants is small and has fewer cells than the wild type.The other has the normal number of cells, though each cell is much smaller than the cells in the wild-type plant.Which hormones are likely to be missing or not functioning properly in these two types of mutants?

A) Cytokinins and gibberellins
B) Auxin and gibberellins
C) Ethylene and gibberellins
D) Gibberellins and brassinosteroids
E) Cytokinins and abscisic acid

Question 40

Which of the following methods is most useful for studying plant signal transduction pathways?

A) Genetic screens of mutants
B) Extensive field tests
C) Careful analysis of seeds
D) Extensive planting programs
E) Data collection in the wild

Question 41

Leaf abscission involves

A) unfolding of the cotyledons during germination.
B) orientation of a leaf toward the light.
C) regeneration of a leaf after a wound.
D) maturation of leaf tissue.
E) separation of leaves from stems.

Question 42

Which of the following promote(s) loosening of the plant cell wall for expansion?

A) Cellulose molecules
B) High pH
C) Acid-activated expansins
D) Water uptake by the vacuole
E) Cross-linking polymers

Question 43

Refer to the figure below showing the changes that occur when a leaf is about to fall from the stem. In this diagram, an abscission zone has formed.What does that mean for the plant?

A) It has been exposed to red light, changing the shape of its phytochrome protein.
B) It has been exposed to far-red light, changing the shape of its phytochrome protein.
C) It has produced insufficient auxin for abscission to take place.
D) Ethylene will trigger the plant to drop its leaves.
E) Auxin will soon initiate fruit production.

Question 44

Which of the following statements about plant tropisms is true?

A) An imbalance in gibberellin concentration causes curvature.
B) Roots grow toward the light.
C) One side of the root or shoot grows more rapidly than the other in response to differences in the amount of auxin present.
D) DNA is the light receptor or gravity receptor.
E) Auxin is the light receptor or gravity receptor.

Question 45

The likely result of treating a shoot cutting with auxin would be

A) root production.
B) suppression of apical dominance.
C) the growth of lateral buds.
D) bolting of the shoot.
E) nothing.

Question 46

In the experiments of Charles and Francis Darwin, which parts of the seedlings were shown to be sensitive to light?

A) The entire seedling
B) The entire shoot above the roots
C) The entire coleoptile
D) The coleoptile region several millimeters below the tip
E) The top millimeter of the tip of the coleoptile

Question 47

Which of the following is the correct sequence of events that causes auxin to move in a polar direction in a plant stem?

A) The ionized auxin is transported into the cell by efflux carriers, the auxin gains a proton in the basic cytosol, and the nonionized auxin passively diffuses out of the base of the cell.
B) Auxin picks up a proton in the basic cell wall space, the nonionized auxin passively diffuses across the cell membrane into the cell, the auxin loses a proton in the more acidic cytosol, the ionized auxin is transported out of the cell by an efflux carrier located only at the base of the cell, and the proton pumps in the cell membrane acidify the cell wall space.
C) Auxin passively diffuses into the cell as an anion, auxin stimulates proton pumps in the cell membrane to acidify the cytosol, the auxin picks up a proton to become uncharged, and the nonionized auxin is actively transported out of the cell by efflux carriers.
D) Proton pumps in the cell membrane acidify the cell wall space, auxin picks up a proton in the acidic cell wall space, the nonionized auxin passively diffuses across the cell membrane into the cell, the auxin loses a proton in the more basic cytosol, and the ionized auxin is transported out of the cell by an efflux carrier located only at the base of the cell.
E) Auxin moves down its concentration gradient from the tip of the plant where it is made to the base where it is used, passively entering and exiting each cell along the way.

Question 48

Apical dominance is most strengthened by

A) removal of the stem tip.
B) auxin production.
C) removal of leaves.
D) production of fruits.
E) removal of fruits.

Question 49

To effectively stop the growth of a plant cell, the most useful thing to do is to stop

A) binding of water to the cell.
B) uptake of water into the vacuole.
C) strengthening of cell-wall components.
D) deposition of new cell-wall materials on the outside of the cell wall.
E) proton-pumping into the cytoplasm.

Question 50

After a few days, a houseplant that has been accidentally knocked on its side will produce shoots that are growing upward relative to its new position.This phenomenon is called

A) positive gravitropism.
B) negative gravitropism.
C) positive phototropism.
D) negative phototropism.
E) positive thigmotropism.

Question 51

In a classic experiment, a gelatin block containing auxin was placed on one edge of a decapitated coleoptile.The result was that the coleoptile

A) grew straight up.
B) grew more on the side with the block.
C) grew more on the side away from the block.
D) grew a new coleoptile tip.
E) did not grow.

Question 52

The discovery of auxin can be traced back to the work of Charles and Francis Darwin and their studies of

A) photosynthesis.
B) photorespiration.
C) photophosphorylation.
D) phototropism.
E) photoperiodism.

Question 53

Experimental removal of the auxin source demonstrates that leaf abscission is _______ by auxin, and apical dominance is _______ by auxin.

A) promoted; also promoted
B) inhibited; also inhibited
C) promoted; inhibited
D) inhibited; promoted
E) promoted; unaffected

Question 54

Which of the following was not one of the observations recorded from work on phototropism?

A) Seedlings were negatively phototropic.
B) Auxin traveled down the stem.
C) Auxin moved somewhat to the shaded side.
D) Auxin was produced in the top 0.5 cm of the coleoptile.
E) Seedlings bent toward the light.

Question 55

The movement of auxin in plants is said to be "polar," which means that auxin

A) is a chemically polar molecule.
B) is produced only in one part of the plant.
C) is primarily transported in only one direction in the plant.
D) moves in a direction away from the light.
E) cannot move through gelatin unless it is bound to a polar molecule.

Question 56

Gravitropism would not be observed in a plant grown in a weightless environment because gravitropism is a phenomenon by which a plant part grows

A) independent of gravitational pull.
B) in a direction determined by gravity.
C) in a direction opposite to that of the main light source.
D) in a direction opposite to that of the growth of the shoot.
E) toward the darkest area.

Question 57

In their experiment with grass coleoptiles, Charles and Francis Darwin observed that the photoreceptor was _______, and the bending took place _______.

A) in the tip; also at the tip
B) below the tip; also below the tip
C) in the tip; below the tip
D) below the tip; throughout the coleoptile
E) in the tip; throughout the coleoptile

Question 58

The plant hormones called auxins do not affect

A) root initiation
B) leaf abscission
C) apical dominance
D) cell expansion
E) inhibition of stem elongation

Question 59

Refer to the figure below showing the changes that occur when a leaf is about to fall from the stem. A decrease in auxin in which region of the diagram would result in formation of the abscission zone?

A) Stem
B) Leaf blade
C) Apical meristem
D) Petiole
E) Stomata

Question 60

Auxin polar transport goes

A) from shoot tip to root tip.
B) from base to tip.
C) either from shoot tip to base or from base to shoot tip.
D) primarily from shoot tip to root tip, but sometimes in reverse.
E) primarily from root tip to shoot tip, but sometimes in reverse.

Question 61

The "wall-loosening factor" present in the cell wall of plants is now believed to be

A) auxins.
B) cellulose-digesting enzymes.
C) starch-digesting enzymes.
D) acid-activated expansins.
E) calcium ions.

Question 62

Which of the following is not involved in the acid growth hypothesis for the regulation of cell expansion by auxin?

A) Pumping of protons into the apoplast
B) Pumping of protons into the cytosol
C) Increased expression of the proton pump gene
D) Increased insertion of proton pumps into the plasma membrane
E) Loosening and expansion of the cell wall

Question 63

Refer to the figure below. Both sets of tomatoes were picked before ripening.The tomatoes on the right are red, while those on the left are still green, because

A) the red tomatoes have been treated with cytokinins.
B) the red tomatoes have been treated with gibberellins.
C) the red tomatoes have been treated with auxin.
D) the red tomatoes have been treated with ethylene.
E) the green tomatoes have been exposed to far-red light.

Question 64

Radishes provide a good demonstration of the pronounced swelling that cytokinins can cause in

A) roots.
B) stems.
C) leaves.
D) flowers.
E) buds.

Question 65

If a mutant plant were created that lacked the receptor for ethylene, its leaves would

A) not expand as much as wild-type leaves.
B) be unable to turn green in the spring.
C) produce excess cytokinins to compensate for the missing ethylene response.
D) be unable to undergo abscission in the fall.
E) develop prematurely in the spring.

Question 66

Florists use silver thiosulfate to

A) delay abscission of petals caused by the action of auxin.
B) delay abscission of leaves caused by the action of abscisic acid.
C) keep petals from turning brown because of the action of ethylene.
D) keep leaves green longer by promoting the action of cytokinins.
E) prevent microbial decay of senescing leaves and petals.

Question 67

An unripe lemon that is placed in a paper bag with an apple will ripen; its skin will yellow, it will soften, and it will produce the characteristic lemon odor.Which plant hormone released by the apple causes this effect?

A) Auxin
B) Ethylene
C) Cytokinins
D) Gibberellins
E) Abscisic acid

Question 68

Refer to the figure below.Each pair includes a dwarf plant with a hormonal deficiency and a normal-sized plant of the same species. By comparing the plants within the same species and then making comparisons between species, you would find that plant hormones

A) always have the same effects.
B) can have the same general effects in different species.
C) operate in dwarf plants.
D) are not present in dwarf plants.
E) have different effects in different plants.

Question 69

Refer to the figure below. The leaf on the left is turning yellow because it is experiencing a natural process known as

A) phototropism.
B) photomorphogenesis.
C) quiescence.
D) etiolation.
E) senescence.

Question 70

What is the difference between the cytokinins kinetin and zeatin?

A) Kinetin is found in aged DNA, whereas zeatin is found in fresh DNA.
B) Kinetin is the active form of zeatin.
C) Zeatin is the active form of kinetin.
D) Zeatin is a naturally occurring plant cytokinin, whereas kinetin is synthetic.
E) Zeatin is a synthetic cytokinin, whereas kinetin is natural.

Question 71

A researcher who wishes to experimentally manipulate leaf senescence in tobacco would apply _______ to promote senescence and _______ to delay it.

A) auxin; cytokinins
B) ethylene; gibberellins
C) ethylene; auxin
D) cytokinins; auxin
E) cytokinins; ethylene

Question 72

Refer to the figure below showing a signal reception pathway. Predict what is most likely to happen when the relevant hormone (e.g., auxin or gibberellin) is present.

A) The plant grows taller.
B) The plant produces more branches.
C) The plant loses its leaves.
D) The plant leans away from a light source (negative phototropism).
E) The fruit is released prematurely by the parent plant.

Question 73

Refer to the figure below showing a signal reception pathway. A mutant plant with an inactive form of the repressor protein (for auxin or gibberellin) is compared to a typical plant.Predict the results of this experiment.

A) The mutant plant is a dwarf because it never transcribes growth promoting genes.
B) The mutant plant transcribes growth promoting genes even in the absence of the relevant hormone.
C) The mutant plant grows more branches than the control plant.
D) The mutant plant does not respond to blue light signals.
E) The mutant plant does not respond to red light signals.

Question 74

A homeowner has set up an outdoor gas-burning grill next to her favorite camellia bush.After the first few nights of using the grill, she notices that the camellia is beginning to lose its leaves.Which statement best explains what is happening?

A) Cytokinins in the plant are activated by the heat of the grill.
B) Ethylene is a by-product of the burning gas and is causing senescence in the plant.
C) Abscisic acid is a by-product of the burning gas and is causing senescence in the plant.
D) The plant is a biennial and is bolting.
E) Auxin production is being inhibited.

Question 75

Unlike other plant hormones, ethylene

A) is not produced by all plants.
B) exerts a number of effects.
C) inhibits plant development.
D) acts either as an inhibitor or a promoter.
E) is a gas.

Question 76

Which cell-division promoting plant hormone is structurally related to a base common in nucleic acids?

A) Abscisic acid
B) Gibberellins
C) Auxin
D) Zeatin
E) Ethylene

Question 77

Refer to the figure below. The leaf on the right is green and healthy because

A) it has been exposed to far-red light.
B) it has been exposed to blue or UV light.
C) it has been treated with ethylene.
D) it has been treated with cytokinins.
E) it is a mutant that lacks a functional brassinosteroid signal transduction pathway.

Question 78

Auxin's polar transport relies in part on the fact that auxin is a weak acid that

A) binds H⁺ in high pH conditions.
B) ionizes to release H⁺ in neutral pH conditions.
C) forms a base in the cell wall.
D) is passively transported across cells.
E) pumps protons across the cell membrane.

Question 79

Refer to the figure below showing a signal reception pathway. What happens when the relevant hormone (e.g., auxin or gibberellin) is absent?

A) The repressor protein prevents transcription of growth promoting genes.
B) The addition of ubiquitin to the repressor is stimulated.
C) The repressor protein is broken down in the proteasome.
D) Genes for the relevant hormone are transcribed.
E) The relevant hormone is produced in the cytoplasm of cell.

Question 80

Which plant hormone stimulates axillary buds to grow into branches?

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