Deck 27: Regulating Growth and Development: the Plant Hormones

Question 1

In roots of Arabidopsis, cytokinin ______ the initiation of lateral roots by preventing the establishment of a(n) ______ gradient.

A)inhibits; auxin
B)inhibits; gibberellin
C)stimulates; auxin
D)stimulates; gibberellin
E)stimulates; ethylene

Answer 1

A

Question 2

______ is very similar to the amino acid tryptophan.

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

Answer 2

C

Question 3

Which of the following statements concerning the role of auxin in developing leaves of Arabidopsis is FALSE?

A)Auxin is produced first at the leaf base and later at the tip.
B)Auxin stimulates the differentiation of vascular tissue.
C)Auxin induces the formation of lateral veins.
D)Auxin is produced by cells that will differentiate into hydathodes.
E)Auxin induces the formation of the midvein.

Answer 3

A

Question 4

Which of the following statements about 2,4-D is FALSE?

A)It is a synthetic auxin.
B)It is used as an herbicide.
C)It is not broken down in plants as readily as IAA.
D)It is absorbed more readily than IAA
E)It kills grasses more readily than broad-leaf weeds. .

Question 5

In studies of leaf senescence, when an excised leaf containing radioactive amino acids is spotted with a kinetin-containing solution, the spot:

A)turns yellow and becomes nonradioactive.
B)turns yellow and becomes more radioactive.
C)remains green and becomes nonradioactive.
D)remains green and becomes more radioactive.
E)turns brown and becomes nonradioactive.

Question 6

Which of the following statements about fruit development is FALSE?

A)A parthenocarpic fruit lacks seeds.
B)A parthenocarpic fruit lacks ovules.
C)Applications of auxin can stimulate carpels to develop into a fruit.
D)Removal of seeds from a developing fruit results in reduced fruit growth.
E)Application of auxin to a deseeded receptacle stimulates fruit growth.

Question 7

A PIN protein:

A)is an auxin influx carrier.
B)is an auxin efflux carrier.
C)catalyzes the conversion of auxin to tryptophan.
D)catalyzes the conversion of auxin to indole.
E)is a synthetic auxin.

Question 8

Which of the following statements concerning strigolactone is FALSE?

A)It is a terpenoid derived from carotenoids.
B)It stimulates bud growth.
C)It is present in root exudates.
D)It promotes the formation of mycorrhizae.
E)It stimulates seed germination of root-parasitic plants.

Question 9

When tobacco pith callus is treated with higher concentrations of auxin than kinetin, ______ is(are) formed.

A)more callus
B)roots
C)buds
D)leaves
E)vascular tissue

Question 10

Which of the following is a phenolic compound with a structure similar to aspirin?

A)systemin
B)florigen
C)brassinosteroids
D)salicylic acids
E)jasmonic acid

Question 11

In stems, polar auxin transport occurs mainly in the:

A)vessels only.
B)sieve tubes only.
C)vascular parenchyma cells only.
D)vessels and sieve tubes.
E)vessels and parenchyma cells.

Question 12

_________ have recently been ranked along with the "classic five" as a major class of plant hormone.

A)Systemins
B)Florigens
C)Brassinosteroids
D)Salicylic acids
E)Jasmonates

Question 13

In apical dominance, the apical bud:

A)inhibits the growth of lateral buds.
B)stimulates the growth of lateral buds.
C)stimulates the upward growth of the stem.
D)stimulates the growth of leaves.
E)inhibits the downward growth of the root.

Question 14

______ activates the biosynthesis of ________, which then activates the genes that encode protease inhibitors.

A)Systemin; jasmonic acid
B)Jasmonic acid; auxin
C)Brassinosteroid; systemin
D)Salicylic acid; jasmonic acid
E)Systemin brassinosteroids

Question 15

Polar transport is ______ in stems, _______in leaves, and ______ in roots.

A)acropetal; acropetal; acropetal
B)basipetal; basipetal; basipetal
C)acropetal; acropetal; basipetal
D)basipetal; acropetal; acropetal
E)basipetal; basipetal; acropetal

Question 16

Folke Skoog and his colleagues found that ______ stimulated cells of tobacco to divide in culture.

A)coconut milk
B)a sugar
C)a salt
D)a vitamin
E)auxin

Question 17

If wounding causes the destruction of vascular tissues in an herbaceous eudicot stem:

A)replacement vascular tissues will not form under any conditions.
B)replacement vascular tissues will form if IAA is added to the stem just below the wound.
C)replacement vascular tissues will form if the leaves and buds above the wound are intact.
D)water will be transported in pith cells instead of in xylem.
E)food will be transported in pith cells instead of in phloem.

Question 18

Which of the following statements about cytokinins is FALSE?

A)They stimulate cell division.
B)They are present in bleeding sap.
C)Kinetin is a naturally occurring cytokinin.
D)They are found primarily in actively dividing tissues and in root tips.
E)The most active naturally occurring cytokinin is zeatin.

Question 19

If a coleoptile tip is covered with a blackened glass tube then illuminated from the side, the coleoptile will:

A)die.
B)not bend.
C)bend toward the light.
D)bend away from the light.
E)bend at right angles to the light.

Question 20

All plant hormones:

A)are equally effective in free and bound forms.
B)act in the tissues where they are produced.
C)are stimulatory.
D)are active in large quantities.
E)communicate information.

Question 21

Which of the following statements about ethylene is FALSE?

A)The final step in its synthesis in plants is catalyzed by enzymes on the tonoplast.
B)Its synthesis in plants begins with the amino acid tryptophan.
C)It exerts an influence on many aspects of plant growth and development.
D)It is the active component of illuminating gas that affects plant development.
E)It has the formula H₂C=CH₂.

Question 22

In Arabidopsis, the ethylene receptor is located in the:

A)endoplasmic reticulum.
B)plasma membrane.
C)Golgi apparatus.
D)chloroplast.
E)nucleus.

Question 23

In the ethylene signaling pathway in Arabidopsis, when the EIN2 protein is activated which of the following happens next?

A)ETR1 undergoes a conformational change.
B)CTR1 is activated.
C)the ethylene signal is transmitted into the nucleus.
D)a transcription factor is activated.
E)genes are activated.

Question 24

The receptors for both auxin and gibberellin are located in the:

A)endoplasmic reticulum.
B)plasma membrane.
C)Golgi apparatus.
D)chloroplast.
E)nucleus.

Question 25

The most widespread and active brassinosteroid is:

A)brassinolide.
B)24-epibrassinolide.
C)S-adenosylmethionine.
D)strigolactone.
E)castasterone.

Question 26

The climacteric is the phase in which fruits undergo a(n):

A)decrease in photosynthesis.
B)decrease in respiration.
C)increase in photosynthesis.
D)increase in respiration.
E)increase in pectin synthesis.

Question 27

In etiolated pea seedlings, ethylene causes ______ longitudinal growth, ______ radial expansion of epicotyls, and ______ growth of epicotyls.

A)increased; increased; horizontal
B)increased; decreased; horizontal
C)decreased; increased; horizontal
D)decreased; increased; angular
E)increased; decreased; angular

Question 28

Which of the following statements concerning endogenous brassinosteroids is FALSE?

A)They are found in virtually every part of the plant.
B)They are synthesized from castasterone.
C)They are essential for tracheary element differentiation.
D)They are required for normal plant growth.
E)They are transported from root to shoot in the xylem.

Question 29

Cell wall extensibility, and thus cell expansion, is increased by ______ but decreased by ______.

A)auxin and ethylene; GA and ABA
B)auxin and GA; ABA and ethylene
C)auxin and ABA; GA and ethylene
D)ABA and ethylene; auxin and GA
E)ABA and GA; auxin and ethylene

Question 30

Gibberellins promote a ______ orientation of the microtubules underlying the plasma membrane, and ethylene promotes a ______ orientation.

A)random; longitudinal
B)transverse; random
C)transverse; longitudinal
D)longitudinal; transverse
E)longitudinal; random

Question 31

Dwarf mutant plants are short because they:

A)synthesize too much gibberellin.
B)synthesize too much abscisic acid.
C)cannot synthesize ethylene.
D)cannot synthesize auxin.
E)cannot synthesize gibberellin.

Question 32

In the ethylene signaling pathway in Arabidopsis, when ethylene is absent, then ____ is active.

A)EIN2
B)CTR1
C)EIN3
D)ERF1
E)Cu

Question 33

In isolated barley aleurone cells, treatment with GA causes the levels of α-amylase to ______, and treatment with ABA causes the levels to ______.

A)increase; remain unchanged
B)decrease; remain unchanged
C)increase; decrease
D)decrease; increase
E)increase; increase

Question 34

In germinating barley seeds, the ______ releases gibberellins, which then diffuse to the ______ where they stimulate the synthesis of hydrolytic enzymes.

A)endosperm; aleurone layer
B)embryo; aleurone layer
C)aleurone layer; embryo
D)aleurone layer; endosperm
E)embryo; seed coat

Question 35

The brassinosteroid receptor differs from the receptors for auxin, gibberellin, ethylene and cytokinins in that the brassinosteroid receptor:

A)is located entirely in the endoplasmic reticulum.
B)has an extracellular region, a transmembrane region, and a cytoplasmic region.
C)is located entirely in the cytoplasm.
D)does not initiate a signaling cascade.
E)binds directly with genes in the nucleus.

Question 36

Which of the following statements about gibberellins is FALSE?

A)They induce bolting in long-day plants.
B)They induce early flowering in biennials.
C)They cause rosette formation in cabbages and carrots.
D)They cause development of parthenocarpic apples and currants.
E)They are used in the commercial production of seedless grapes.

Question 37

If cell wall microfibrils are oriented transversely, the cell normally expands:

A)in all directions.
B)at an oblique angle.
C)first laterally and then longitudinally.
D)laterally.
E)longitudinally.

Question 38

Which of the following statements about abscisic acid is FALSE?

A)It has no direct role in abscission.
B)It induces the closing of stomata.
C)It prevents premature seed germination.
D)It inhibits the production of seed storage proteins.
E)It is produced during water stress.

Question 39

Cytokinins are synthesized in ____ and transported from there to all other parts of the plant.

A)stems
B)shoot apical meristems
C)leaves
D)roots
E)fruits

Question 40

In the acid-growth hypothesis of cell wall extensibility, which of the following events occurs FIRST?

A)Expansins disrupt hydrogen bonds.
B)Protons are pumped into the cell wall.
C)Specific genes are activated.
D)A proton-pumping enzyme is activated.
E)Cross-links between noncellulosic polysaccharides are broken.

Question 41

Auxin is the only plant hormone known to be transported in a polar manner.

Question 42

In roots, a substance transported in a basipetal direction is transported toward the root tip.

Question 43

Recent evidence indicates that auxin does not directly inhibit the growth of lateral buds.

Question 44

Which of the following statements about second messengers is FALSE?

A)They amplify the signal produced by a hormone.
B)They contribute to the diversity of responses to a hormone.
C)They transfer information from the hormone-receptor complex to the target protein.
D)An example is protein kinase.
E)An example is calcium ion.

Question 45

The weed killer 2,4-D is a synthetic cytokinin.

Question 46

Gibberellins promote fruit development in some species in which auxin does not.

Question 47

Application of cytokinin inhibits the growth of lateral buds.

Question 48

The transport of auxin can be nonpolar as well as polar.

Question 49

One of the principal roles of abscisic acid is in leaf, flower, and fruit abscission.

Question 50

Mutants of Arabidopsis that lack brassinosteroids have leaves that are smaller and have fewer cells than the wild-type.

Question 51

In climacteric fruits, there is a large increase in cellular respiration during ripening.

Question 52

Cytokinins are synthesized in roots and transported in the xylem to other parts of the plant.

Question 53

Rice plants grow rapidly and become spindly due to the presence of gibberellic acid produced by a fungus.

Question 54

In the ABA-induced closing of stomata, the following ion fluxes occur across guard cell plasma membranes: first calcium ions flow ______, then anions flow ______, and finally potassium ions flow ______.

A)in; out; out
B)in; in; in
C)out; in; out
D)out; out; in
E)out; out; out
True-False Questions

Question 55

An excised leaf floated in a kinetin solution will remain green longer than a leaf floated in water.

Question 56

Salicylic acid regulates thermogenesis in members of the arum family.

Question 57

Plant hormones usually act alone and only occasionally "cross-talk."

Question 58

Jasmonic acid has a structure similar to aspirin.

Question 59

If you cut the tip off a bean plant, the lateral buds will stop developing.

Question 60

Ethylene stimulates internodal elongation of rice plants that are submerged during monsoon flooding.

Question 61

A cortical cell and a mesophyll cell from the same plant most likely have different genes in their nuclei.

Question 62

Expansins are proteins that disrupt hydrogen bonds between cell wall polysaccharides.

Question 63

Based on the results of experiments with cultured mesophyll cells of Zinnia elegans, you would predict that if brassinosteroids were excluded from the culture medium, no tracheary elements would be formed.

Question 64

Second messengers do not cross the plasma membrane and enter the cytosol.

Question 65

In Arabidopsis, the ethylene receptor is located in the plasma membrane.