CHAPTER 41
B
10. Which of the following traits does not apply to brassinosteroids? A. They were first discovered in pollen. B. They are released from the cell wall by enzymes secreted by pathogens. C. Their functions overlap with those of auxins and gibberellins. D. Their characteristics are similar to animal steroids. E. They may have evolved before the evolutionary divergence of plants and animals.
D
13. Which gaseous hormone stimulates the ripening of fruits? A. abscisic acid B. gibberellin C. indoleacetic acid D. ethylene E. cytokinin
D
17. Which of these is not one of the steps that lead to a gravitropic response in plants? A. Signals form in the cell that perceives the stimulus. B. Differential cell elongation occurs. C. Auxin accumulates unevenly on opposite sides of the stem or root, stimulating the bending in response to gravity. D. Amyloplasts float upward inside the perceptive cells. E. Hormone signals are transported away from the tips of the roots or shoots.
D
18. Which of the following statements about hormones is false? A. They are chemical signals produced in the organism. B. They are produced in small, often minute quantities. C. They are produced in one part of the organism and transported to another. D. Their effect is the same throughout the organism. E. They can stimulate certain physiological processes while inhibiting others.
E
25. Which of the following is not a characteristics of cytokinins? A. stimulate cell division B. inhibit growth of lateral roots C. related to or derived from adenine D. help determine the course of tissue differentiation E. accelerate leaf aging
D
29. The plant hormone that is functional as a gas is A. auxin. B. abscisic acid. C. cytokinin. D. ethylene. E. gibberellin.
A
38. During a viticulturist's presentation on growing and managing grapes, why did he state that it is imperative to encourage the grapevine's natural tendency for positive thigmotropism? A. To encourage the vine's response to move toward the early morning light as opposed to the late afternoon sun. B. To encourage the roots to grow deeper and spread out. C. To encourage the grapes to retain their sugar for a longer period of time. D. To encourage the twining stems to wrap around the supporting wires. E. To encourage the self-pruning that is natural to grapevines.
B
42. All of the following are uses of synthetic auxins, such as NAA and IBA, in agriculture and horticulture except A. to promote flowering and fruiting in pineapples. B. to prevent fruit drop. C. to induce formation of roots in plant cuttings. D. to prevent leaf and fruit abscission. E. to produce bushier plants.
B
45. A plant physiologist treats a leaf with abscisic acid and observes that the stomata close. What happened inside the guard cells during the experiment? A. Abscisic acid influences the movement of sodium ions out of the guard cells. B. Abscisic acid influences the movement of potassium ions out of the guard cells. C. Abscisic acid binds carbon dioxide and causes carbonate crystals to block the stomatal opening. D. Abscisic acid binds with auxins and induces water molecules to exit the guard cells. E. Abscisic acid causes the guard cells to become more turgid.
B
50. Removing the apical bud of a stem usually results in A. faster flowering. B. a bushier plant. C. stunted growth. D. leaf abscission. E. starch accumulation.
C
54. Before ARF transcription factors can trigger auxin-induced gene expression, what must happen? A. Auxin binds to ubiquitin, a degradation tag. B. Auxin degrades Aux/IAA proteins which repress ARF transcription factors. C. Auxin binds to TIR1, an auxin receptor. D. Auxin must bind to the ARF transcription factor. E. Ubiquitin must destroy TIR1 to release Aux/IAA proteins.
A
9. The plant hormones known as ___________ are structurally similar to animal steroid hormones. A. brassinosteroids B. oligosaccharides C. cytokinins D. auxins E. abscisic acids
E
A compound similar to auxin, 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), has been used A. as a fertilizer for corn and wheat. B. as a spray to promote flowering of pineapple. C. as an organic substitute for chlorine bleach. D. to detoxify the dangerous poison dioxin. E. an herbicide for killing weeds and woody seedlings.
B
A scientist is investigating a hormone response in rose bush stems. The apical meristems of the main stems were removed to allow the lateral buds to develop. What hormone will induce the development of lateral buds once the apical meristems are removed? A. auxin B. cytokinin C. gibberellin D. abscisic acid E. ethylene
C
A viticulturist wants to grow larger grapes. A plant physiologist suggests which specific hormone treatment to increase the internode lengths of the plants? A. auxin B. cytokinin C. gibberellin D. abscisic acid E. ethylene
B
Abscisic acid suppresses growth of buds and promotes A. lengthening. B. dormancy. C. rolling. D. color change. E. development.
D
Auxin from the apical bud A. stimulates the growth of lateral buds. B. inhibits the transport of sucrose towards the roots. C. stimulates the growth of leaves. D. inhibits the growth of lateral buds. E. inhibits tip elongation.
C
Charles Darwin and his son experimented with which plant growth response? A. gravitropism B. circadian rhythms C. phototropism D. heat shock E. thermotropism
C
Coconut milk was an extremely useful additive in plant tissue culture because, in addition to amino acids, it contains A. auxins. B. gibberellins. C. cytokinins. D. ethylene. E. abscisic acid.
A
Cytokinins are related to or derived from which purine base? A. adenine B. thymine C. guanine D. cytocine E. uracil
B
Cytokinins promote cell division and differentiation in plant tissues, but only in the presence of what other plant hormone? A. auxin B. ethylene C. abscisic acid D. gibberellin E. oligosaccharin
B
Directional, light-triggered plant development is known as A. thigmotropism. B. phototropism. C. thigmonasty. D. photomorphogenesis. E. acid-growth movement.
C
Ethylene plays a number of roles in plants, including all of the following except A. retarding stem and root elongation. B. hastening the ripening of fruits. C. increasing the storage life of apples, bananas, and oranges. D. accelerating the loss of damaged leaves and fruits. E. retarding lateral bud growth.
A
Gibberellins were first identified in A. rice. B. apples. C. bananas. D. tomatoes. E. grapes.
C
How do nastic movements differ from tropisms? A. Nastic movements are slower than tropisms. B. Nastic movements only occur in the dark. C.Tropisms are directional responses to directional stimuli; nastic movements are the same regardless of the direction of the stimulus. D. Nastic movements happen after a stimulus, tropisms happen during a stimulus. E. Nastic movements are not reversible.
D
If temperatures suddenly rise 5 to 10o C, __________ proteins are produced to help stabilize other proteins. A. denatured B. photosensitive C. chilling D. heat shock E. oxidative
D
In Arabidopsis plants, about 10% of its genome is devoted to processes tied to which molecule? A. auxin B. ubiquitin C. rubisco D. phytochrome E. gibberellins
B
In some genetically engineered tomatoes, fruit ripening was delayed by crippling the gene that produces which hormone? A. auxin B. ethylene C. abscisic acid D. gibberellin E. cytokinin
A
Mature plants may become __________ in dry or cold seasons in order to survive long periods that are unfavorable for growth. A. dormant B. dehydrated C. photoperiodic D. thigmonastic E. gravitropic
E
Most dwarf plants are mutants that A. produce too much gibberellin. B. cannot produce auxin. C. produce too much cytokinin. D. have defective auxin receptors. E. cannot produce gibberellin.
B
One effect of auxin, which triggers the elongation of cells, is to affect cell walls by increasing their A. permeability. B. plasticity. C. stiffness. D. thickness. E. water solubility.
B
Rapid turgor pressure changes in specialized multicellular swellings called ____________ are associated with leaves that move in response to touch or light. A. petioles B. pulvini C. stipules D. pudicas E. coleoptiles
A
Red light and phytochrome are involved in all of the following plant growth responses except A. thigmotropic responses. B. inhibition of seed germination. C. elongation of etiolated shoots. D. signals for overlapping distances between plants. E. photomorphogenesis.
C
The directional growth response of plants to touch is called A. phototropism. B. gravitropism. C. thigmotropism. D. photoperiodism. E. thermotropism.
D
The elongation of stems is stimulated by A. auxin only. B. gibberellin only. C. ethylene only. D. auxin and gibberellin. E. auxin and ethylene.
E
Turgor movements in plants are responsible for all of the following actions except A. reversible changes in water pressure within plant cells. B. reduction of water loss from transpiration. C. folding of leaflets in the Mimosa pudica plants. D. flowers that open during the day and close at night. E. inducing changes in the active form of phytochrome.
A
What color of light triggers the phototropic response in coleoptiles? A. blue B. green C. yellow D. red E. far-red
C
What endogenous process helps plants to keep their movements and other responses synchronized with the environment? A. purine monitoring B. solar tracking C. a circadian clock D. auxin cycling E. gravitropism
C
What happens when coleoptiles are illuminated with directional light from the side instead of from directly overhead? A. More auxin is produced. B. Less auxin is produced. C. Auxin is transported away from the lighted side. D. Auxin is transported toward the lighted side. E. Auxin receptors are activated.
B
When Darwin covered the tip of a grass seedling with metal foil and then illuminated it from one side, what happened to the seedling? A. It bent away from the directional light. B. It did not respond to the directional light. C. It grew toward the light, as expected. D. It waved back and forth. E. It wilted and died.
C
When gibberellin binds to its receptor, what happens to activate the gibberellin-dependent transcription factor GA-TRXN? A. Ethylene is released. B. A ubiquitin tag is used to degrade the GA-TRXN inhibitor. C. A DELLA protein is degraded, freeing the GA-TRXN. D. A DELLA protein is attached to GA-TRXN to activate it. E. The gibberellin is transferred to an alternate binding site.
C
When one plant is shaded by another, why is the ratio of far-red to red light increased compared to an unshaded plant? A. Phytochrome in the taller plant absorbs most of the red light. B. Auxin absorbs mostly far-red light. C. As light passes through the leaves of the taller plant, most of the red light is absorbed by chlorophyll. D. Far-red light mostly reflects off the surface of the soil while red light is mostly absorbed. E. Shade is enriched in far-red wavelengths of light.
A
Which naturally-occurring plant hormone has a major role in the phototropic response of plants? A. auxin B. gibberellin C. abscisic acid D. ethylene E. 2, 4-D
B
Which of the following actions is not a major function of auxins? A. inhibition of leaf abscission B. promotion of seed germination C. stimulation of the elongation of cells by acting on cell walls D. stimulation of the formation of roots on cuttings E. promotion of the activity of the vascular cambium
B
Which of the following is not one of the seven major kinds of plant hormones? A. auxin B. nitrogen oxide C. cytokinin D. gibberellin E. ethylene
A
Which of the following plant hormones promotes fruit ripening? A. ethylene B. gibberellin C. cytokinin D. auxin E. abscisic acid
B
Which of the following statements about abscisic acid is false? A. It is produced chiefly in mature green leaves and in fruits. B. It stimulates the growth of dormant buds. C. It promotes leaf senescence. D. It plays an important role in controlling the opening and closing of stomata. E. It plays a role in seed dormancy.
D
Which of the following statements about gravitropism is false? A. Shoots exhibit negative gravitropism. B. Amyloplasts play a role in perceiving gravity. C. Gravitropic responses are evident at germination. D. Ethylene is important in plants' responses to gravity. E. In roots, the gravity-sensing cells are located in the root cap.
A
Which of the following statements about phototropisms is false? A. They mostly occur through a response to green light and an estradiol receptor. B. They include bending of plant stems toward light. C. Occasionally roots exhibit a weak negative phototropic response. D. They help plants position themselves better toward available light. E. They can influence the development of plant organs.
C
Which of the following statements about phytochrome is not true? A. It exists in two interconvertible forms. B. PR absorbs red light. C. PFR is biologically inactive. D. PFR reverts to PR in the dark. E. Several versions of phytochrome exist with overlapping but distinctive functions.
E
Which of these is not true about gibberellins? A. They are produced in the apical regions of shoots and roots. B. They promote internode elongation. C. They can be applied to certain dwarf mutants to restore normal growth and development. D. They hasten seed germination. E. They inhibit amylases and other hydrolytic enzymes in seeds.
D
Which tropism is not correctly matched with its meaning? A. phototropism—response to light B. gravitropism—response to gravity C. thigmotropism—response to touch D. thermotropism—response to temperature E. heliotropism—response to carbon dioxide
C
_______________ are chemical substances produced in small quantities in one part of an organism and then transported to another part of the organism, where they bring about physiological responses. A. Glycoproteins B. Photosynthates C. Hormones D. Heat shock proteins E. Pulvini
B
________________ are complex carbohydrates that are released from plant cell walls and appear to regulate both pathogen responses and growth and development in some plants. A. Brassinosteroids B. Oligosaccharides C. Cytokinins D. Auxins E. Glycoproteins
D
________________ is directional growth responses of plants to a unidirectional source of light. A. Gravitropism B. Thigmotropism C. Dormancy D. Phototropism E. Thermotropism
E
everal scientists, including Charles and Francis Darwin, Frits Went and others, demonstrated that auxins caused stems to bend toward light in a series of elaborate experiments. Went was the researcher who finally determined that bending of the stem toward light was a result of which mechanism? ALight caused a reduction in auxin concentration and a reduction in stem elongation on the lighted side . of the plant stem, and thus a bending in the direction of the light. B.The transport of auxin to the shaded side of the plant stem stimulated stem elongation and a bending in the direction of the light. C Auxin concentration was equal on both sides (lighted and shaded) of the stem; however, the apical . meristemrespondedtothepresenceoflight. D. A combination of positive phototropism and a negative gravitropism. E. The stems actually were responding to the agar blocks that had been used in the experiments.
C
he acid-growth hypothesis links A. oligosaccharins to pH changes. B. cytokinin to thigmonasty. C. auxin to cell wall expansion. D. gibberellin to root elongation. E. ethylene to leaf abscission.
B
he hormone _________ has a more pronounced role in stem elongation if auxin is also present. A. ethylene B. gibberellin C. cytokinin D. abscisic acid E. brassinolide
D
kototropism is an unusual tropism based on growth toward darkness rather than toward light as in phototropism. Which of these is an example? A. plants growing in the shade of another plant B. germinating seedlings growing through the soil C. root tips growing in the soil D. vine seedlings on the forest floor searching for tree trunks to climb E. night-blooming flowers
