ch 39 practice problems

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73) A pathogenic fungus invades a plant. What does the infected plant produce in response to the attack? A) antisense RNA B) phytoalexins C) phytochrome D) statoliths E) thickened cellulose microfibrils in the cell wall

B Topic: Concept 39.5 Skill: Knowledge

92) Auxin triggers the acidification of cell walls that results in rapid growth, but also stimulates sustained, long-term cell elongation. What best explains how auxin brings about this dual growth response? A) Auxin binds to different receptors in different cells. B) Different concentrations of auxin have different effects. C) Auxin causes second messengers to activate both proton pumps and certain genes. D) The dual effects are due to two different auxins. E) Other antagonistic hormones modify auxin's effects.

93) If a scientist discovered an Arabidopsis mutant that did not store starch in its plastids but underwent normal gravitropic bending, what aspect of our current understanding of root gravitropism would have to be reevaluated? A) the role of auxin in gravitropism B) the role of calcium in gravitropism C) the role of statoliths in gravitropism D) the role of light in gravitropism E) the role of differential growth in gravitropic bending

85) Which of the following is not a typical component of a signal transduction pathway? A) production of more signal B) production of second messengers such as cGMP C) expression of specific proteins D) activation of protein kinases E) phosphorylation of transcription factors

4) External stimuli would be received most quickly by a plant cell if the receptors for signal transduction were located in the A) cell membrane. B) cytoplasmic matrix. C) endoplasmic reticulum. D) nuclear membrane. E) nucleoplasm.

A Topic: Concept 39.1 Skill: Comprehension

27) The heavy line in Figure 39.1 illustrates the relationship between auxin concentration and cell growth in stem tissues. If the same range of concentrations were applied to lateral buds, what curve would probably be produced? A) I B) II C) III D) II and III E) either I or III

A Topic: Concept 39.2 Skill: Application

10) Charles and Francis Darwin concluded from their experiments on phototropism by grass seedlings that the part of the seedling that detects the direction of light is the A) tip of the coleoptile. B) part of the coleoptile that bends during the response. C) root tip. D) cotyledon. E) phytochrome.

A Topic: Concept 39.2 Skill: Knowledge

15) Evidence for phototropism due to the asymmetric distribution of auxin moving down the stem A) has not been found in eudicots such as sunflower and radish. B) has been found in all monocots and most eudicots. C) has been shown to involve only IAA stimulation of cell elongation on the dark side of the stem. D) can be demonstrated with unilateral red light, but not blue light. E) is now thought by most plant scientists not to involve the shoot tip.

A Topic: Concept 39.2 Skill: Knowledge

14) Which of the following is not presently considered a major mechanism whereby hormones control plant development? A) affecting cell respiration via regulation of the citric acid cycle B) affecting cell division via the cell cycle C) affecting cell elongation through acid growth D) affecting cell differentiation through altered gene activity E) mediating short-term physiological responses to environmental stimuli

A Topic: Concept 39.2 Skill: Knowledge

46) Plants often use changes in day length (photoperiod) to trigger events such as dormancy and flowering. It is logical that plants have evolved this mechanism because photoperiod changes A) are more predictable than air temperature changes. B) alter the amount of energy available to the plant. C) are modified by soil temperature changes. D) can reset the biological clock. E) are correlated with moisture availability.

A Topic: Concept 39.3 Skill: Application

55) If you take a short-day plant and put it in a lab under conditions where it will flower (long nights and short days), but interrupt its day period with a few minutes of darkness, what will happen? A) It will flower. B) It will not flower. C) It will die. D) It will lose its ability to photosynthesize. E) It will form new shoots from the axillary buds.

A Topic: Concept 39.3 Skill: Comprehension

39) Both red and blue light are involved in A) stem elongation. B) photoperiodism. C) positive phototropism. D) tracking seasons. E) all of the above

A Topic: Concept 39.3 Skill: Knowledge

58) A botanist discovers a plant that lacks the ability to form starch grains in root cells, yet the roots still grow downward. This evidence refutes the long-standing hypothesis that A) falling statoliths trigger gravitropism. B) starch accumulation triggers the negative phototropic response of roots. C) starch grains block the acid growth response in roots. D) starch is converted to auxin, which causes the downward bending in roots. E) starch and downward movement are necessary for thigmotropism.

A Topic: Concept 39.4 Skill: Application

63) If you wanted to genetically engineer a plant to be more resistant to drought, increasing amounts of which of the following hormones might be a good first attempt? A) abscisic acid B) brassinosteroids C) gibberellins D) cytokinins E) auxin

A Topic: Concept 39.4 Skill: Application

68) Bald cypress and Loblolly pine are both gymnosperm trees native to the southern United States. The cypress grows in swamps; the pine grows in sandy soil. How do you think their anatomies differ? A) There are larger intercellular spaces in the roots of the cypress than in the roots of the pine. B) Water-conducting cells are larger in the stems of the cypress than in the stems of the pine. C) The springwood and summerwood are more distinct in the cypress. D) There is less parenchyma in the roots of the cypress than in the pine roots. E) There are no major anatomical differences between these species because they're both gymnosperms.

A Topic: Concept 39.4 Skill: Application

62) You are part of a desert plant research team trying to discover crops that will be productive in arid climates. You discover a plant that produces a guard cell hormone under water-deficit conditions. Most likely the hormone is A) ABA. B) GA. C) IAA. D) 2, 4-D. E) salicylic acid.

A Topic: Concept 39.4 Skill: Knowledge

70) In general, which of the following is not a plant response to herbivores? A) domestication, so that humans can protect the plant B) attracting predatory animals, such as parasitoid wasps C) chemical defenses, such as toxic compounds D) physical defenses, such as thorns E) production of volatile molecules

A Topic: Concept 39.5 Skill: Knowledge

82) What is the specific term that refers to seasonal changes in the relative lengths of night and day? A) photoperiod B) circadian rhythm C) chemotaxis D) gravitropism E) phototaxis

A Topic: Web/CD Activity: Flowering Lab

79) The breakdown of chlorophyll reveals the ________ pigments of a leaf. A) carotenoid B) xanthophyll C) anthocyanin D) melanin E) phycoerythrin

A Topic: Web/CD Activity: Leaf Abscission

81) After leaf abscission, growth will resume from the A) petiole. B) protective layer. C) palisade layer. D) axillary bud. E) abscission layer.

A Topic: Web/CD Activity: Leaf Abscission

90) If a long-day plant has a critical night length of 9 hours, which of the following 24-hour cycles would prevent flowering? A) 16 hours light/8 hours dark B) 14 hours light/10 hours dark C) 15.5 hours light/8.5 hours dark D) 4 hours light/8 hours dark/4 hours light/8 hours dark E) 8 hours light/8 hours dark/light flash/8 hours dark

84) Which hormone is incorrectly paired with its function? A) auxin—promotes stem growth through cell elongation B) cytokinins—initiate programmed cell death C) gibberellins—stimulate seed germination D) abscisic acid—promotes seed dormancy E) ethylene—inhibits cell elongation

86) Buds and sprouts often form on tree stumps. Which of the following hormones would you expect to stimulate their formation? A) auxin B) cytokinins C) abscisic acid D) ethylene E) gibberellins

88) The signal for flowering could be released earlier than normal in a long-day plant experimentally exposed to flashes of A) far-red light during the night. B) red light during the night. C) red light followed by far-red light during the night. D) far-red light during the day. E) red light during the day.

91) The probable role of salicylic acid in systemic acquired resistance of plants is to A) destroy pathogens directly. B) activate plant defenses throughout the plant before infection spreads. C) close stomata, thus preventing the entry of pathogens. D) activate heat-shock proteins. E) sacrifice infected tissues by hydrolyzing cells.

71) In order for a plant to initiate chemical responses to herbivory, A) the plant must be directly attacked by an herbivore. B) volatile "signal" compounds must be perceived. C) gene-for-gene recognition must occur. D) phytoalexins must be released. E) all of the above must happen.

B Topic: Concept 39.5 Skill: Comprehension

5) Secondary messengers are associated with which of the following? A) reception B) transduction C) response D) both A and B E) both B and C

B Topic: Concept 39.1 Skill: Knowledge

2) All of the following may function in signal transduction in plants except A) calcium ions. B) nonrandom mutations. C) receptor proteins. D) phytochrome. E) second messengers.

B Topic: Concept 39.1 Skill: Knowledge

16) Vines in tropical rain forests must grow toward large trees before being able to grow toward the sun. To reach a large tree, the most useful kind of growth movement for a tropical vine presumably would be the opposite of A) positive thigmotropism. B) positive phototropism. C) positive gravitropism. D) sleep movements. E) circadian rhythms.

B Topic: Concept 39.2 Skill: Application

36) We tend to think of plants as immobile when, in fact, they can move in many ways. All of the following are movements plants can accomplish except A) growth movements up or down in response to gravity. B) folding and unfolding of leaves using muscle-like tissues. C) growth movements toward or away from light. D) changes in plant growth form in response to wind or touch. E) rapid responses using action potentials similar to those found in the nervous tissue of animals.

B Topic: Concept 39.2 Skill: Comprehension

23) Which of the following has not been established as an aspect of auxin's role in cell elongation? A) Auxin instigates a loosening of cell wall fibers. B) Auxin increases the quantity of cytoplasm in the cell. C) Through auxin activity, vacuoles increase in size. D) Auxin activity permits an increase in turgor pressure. E) Auxin stimulates proton pumps.

B Topic: Concept 39.2 Skill: Comprehension

22) Which plant hormones might be used to enhance stem elongation and fruit growth? A) brassinosteroids and oligosaccharides B) auxins and gibberellins C) abscisic acid and phytochrome D) ethylene and cytokinins E) phytochrome and flowering hormone

B Topic: Concept 39.2 Skill: Knowledge

26) Which plant hormone(s) is (are) most closely associated with cell division? A) ethylene B) cytokinin C) abscisic acid D) phytochrome E) brassinosteroids

B Topic: Concept 39.2 Skill: Knowledge

47) If the range of a species of plants expands to a higher latitude, which of the following processes is the most likely to be modified by natural selection? A) circadian rhythm B) photoperiodic response C) phototropic response D) biological clock E) thigmomorphogenesis

B Topic: Concept 39.3 Skill: Application

45) The biological clock controlling circadian rhythms must ultimately A) depend on environmental cues. B) affect gene transcription. C) stabilize on a 24-hour cycle. D) speed up or slow down with increasing or decreasing temperature. E) do all of the above.

B Topic: Concept 39.3 Skill: Comprehension

43) In legumes, it has been shown that "sleep" movements are correlated with A) positive thigmotropisms. B) rhythmic opening and closing of K+ channels in motor cell membranes. C) senescence (the aging process in plants). D) flowering and fruit development. E) ABA-stimulated closing of guard cells caused by loss of K+.

B Topic: Concept 39.3 Skill: Knowledge

56) Florigen is a flowering signal, not yet chemically identified, found in A) flowers. B) leaves. C) roots. D) seeds. E) floral buds.

B Topic: Concept 39.3 Skill: Knowledge

60) When transplanting a tree, it is recommended to loosely attach three or four guylines. The purpose of leaving these supports loose is to A) prevent constriction of secondary growth. B) permit moderate bending to stimulate thickness growth. C) allow room for expansion as the tree grows taller. D) B and C only E) A, B, and C

B Topic: Concept 39.4 Skill: Application

57) What do results of research on gravitropic responses of roots and stems show? A) Different tissues have the same response to auxin. B) The effect of a plant hormone can depend on the tissue. C) Some responses of plants require no hormones at all. D) Light is required for the gravitropic response. E) Cytokinin can only function in the presence of auxin.

B Topic: Concept 39.4 Skill: Comprehension

65) Most scientists agree that global warming is underway; thus it is important to know how plants respond to heat stress. Which of the following is an immediate short-term response of plants to heat stress? A) the production of heat-shock carbohydrates unique to each plant B) the production of heat-shock proteins like those of other organisms C) the opening of stomata to increase evaporational heat loss D) their evolution into more xerophytic plants E) all of the above

B Topic: Concept 39.4 Skill: Knowledge

80) The protective layer that forms between the abscission layer and the stem consists of A) a layer of green palisade cells. B) weak, colorless, thin-walled cells. C) mycorrhizae. D) irregularly shaped cells with very thick-lignified secondary walls. E) densely colored cells filled with a waxy layer

B Topic: Web/CD Activity: Leaf Abscission

7) What would happen if the secondary messenger cGMP was blocked in the de-etiolation pathway? A) Specific protein kinase 1 would be activated, and greening would occur. B) Ca2+ channels would not open, and no greening would occur. C) Ca2+ channels could open, and specific protein kinase 2 could still be produced. D) No transcription of genes that function in de-etiolation would occur. E) Transcription of de-etiolation genes in the nucleus would not be affected.

C Topic: Concept 39.1 Skill: Application

3) Which of the following statements is (are) true of plants? A) Unlike animals, plants cannot respond to stimuli. B) Plants are stationary and are incapable of movement. C) Plants adjust their growth and development in response to environmental cues. D) Only A and B are true. E) A, B, and C are true.

C Topic: Concept 39.1 Skill: Comprehension

30) This experiment suggests that the unknown amount of gibberellin in the experimental plant (B) is approximately A) zero. B) 0.01 μg/mL. C) 0.1 μg/mL. D) 1.0 μg/mL. E) equal to the amount of gibberellin in the shortest plant.

C Topic: Concept 39.2 Skill: Application

34) If you were shipping green bananas to a supermarket thousands of miles away, which of the following chemicals would you want to eliminate from the plants' environment? A) CO2 B) cytokinins C) ethylene D) auxin E) gibberellic acids

C Topic: Concept 39.2 Skill: Application

12) Which of these conclusions is supported by the research of both Went and Charles and Frances Darwin on shoot responses to light? A) When shoots are exposed to light, a chemical substance migrates toward the light. B) Agar contains a chemical substance that mimics a plant hormone. C) A chemical substance involved in shoot bending is produced in shoot tips. D) Once shoot tips have been cut, normal growth cannot be induced. E) Light stimulates the synthesis of a plant hormone that responds to light.

C Topic: Concept 39.2 Skill: Comprehension

13) We know from the experiments of the past that plants bend toward light because A) they need sunlight energy for photosynthesis. B) the sun stimulates stem growth. C) cell expansion is greater on the dark side of the stem. D) auxin is inactive on the dark side of the stem. E) phytochrome stimulates florigen production.

C Topic: Concept 39.2 Skill: Comprehension

28) The application of which of the following hormones would be a logical first choice in an attempt to produce normal growth in mutant dwarf plants? A) indoleacetic acid B) cytokinin C) gibberellin D) abscisic acid E) ethylene

C Topic: Concept 39.2 Skill: Knowledge

17) Plant hormones can be characterized by all of the following except that they A) may act by altering gene expression. B) have a multiplicity of effects. C) function independently of other hormones. D) control plant growth and development. E) affect division, elongation, and differentiation of cells.

C Topic: Concept 39.2 Skill: Knowledge

38) Incandescent light bulbs, which have high output of red light, are least effective in promoting A) photosynthesis. B) seed germination. C) phototropism. D) flowering. E) entrainment of circadian rhythms.

C Topic: Concept 39.3 Skill: Application

40) Seed packets give a recommended planting depth for the enclosed seeds. The most likely reason some seeds are to be covered with only 1/4 inch of soil is that the A) seedlings do not produce a hypocotyl. B) seedlings do not have an etiolation response. C) seeds require light to germinate. D) seeds require a higher temperature to germinate. E) seeds are very sensitive to waterlogging.

C Topic: Concept 39.3 Skill: Application

42) The houseplants in a windowless room with only fluorescent lights begin to grow tall and leggy. Which of the following treatments would promote more normal growth? A) Leave the lights on at night as well as during the day. B) Add additional fluorescent tubes to increase the light output. C) Add some incandescent bulbs to increase the amount of red light. D) Set a timer to turn on the lights for 5 minutes during the night. E) Turn off the lights for 5 minutes during the day.

C Topic: Concept 39.3 Skill: Application

54) Suppose there is a large deciduous ornamental tree on your campus and the city places a very bright street light right next to it on a tall pole. A botanist on the faculty complains to the city council and asks them to remove the light. Most likely the botanist is concerned because the light A) will alter the photosynthetic rate of the tree and keep it growing at night. B) may cause the stomata to close because of increased ABA synthesis. This could starve the tree for CO2 and it could die. C) may change the photoperiod and cause the tree to retain its leaves during the winter. This could cause dehydration and loss of the tree. D) will cause the tree to bend toward the light on the pole, and the tree could fall. E) will stimulate ethylene production, premature senescence, and early death of the tree.

C Topic: Concept 39.3 Skill: Application

41) Most plants close their stomata at night. What color of light would be most effective in promoting stomatal opening in the middle of the night? A) red B) far-red C) blue D) red followed by far-red E) far-red followed by blue

C Topic: Concept 39.3 Skill: Knowledge

61) Which of the following watering regimens will be most effective at keeping a lawn green during the hot, dry summer months? A) daily sprinkling to soak the soil to 0.5 inch B) sprinkling every other day to soak the soil to 1.0 inch C) sprinkling every third day to soak the soil to 2.0 inches D) A or B would be equally effective. E) A, B or C would be equally effective.

C Topic: Concept 39.4 Skill: Application

69) The initial response of the root cells of a tomato plant watered with seawater would be to A) rapidly produce organic solutes in the cytoplasm. B) rapidly expand until the cells burst. C) begin to plasmolyze as water is lost. D) actively transport water from the cytoplasm into the vacuole. E) actively absorb salts from the seawater.

C Topic: Concept 39.4 Skill: Application

67) All of the following are responses of plants to cold stress except A) the production of a specific solute "plant antifreeze" that reduces water loss. B) excluding ice crystals from the interior walls. C) conversion of the fluid mosaic cell membrane to a solid mosaic one. D) an alteration of membrane lipids so that the membranes remain flexible. E) increasing the proportion of unsaturated fatty acids in the membranes.

C Topic: Concept 39.4 Skill: Comprehension

75) The transduction pathway that activates systemic acquired resistance in plants is initially signaled by A) antisense RNA. B) Pfr phytochrome. C) salicylic acid. D) abscisic acid. E) red, but not far-red, light.

C Topic: Concept 39.5 Skill: Knowledge

87) Which of the following is not part of the acid growth hypothesis? A) Auxin stimulates proton pumps in cell membranes. B) Lowered pH results in the breakage of cross-links between cellulose microfibrils. C) The wall fabric becomes looser (more plastic). D) Auxin-activated proton pumps stimulate cell division in meristems. E) The turgor pressure of the cell exceeds the restraining pressure of the loosened cell wall, and the cell takes up water and elongates.

8) If protein synthesis was blocked in etiolated cells, what would be necessary for any de-etiolation to occur? A) reception of light by phytochrome B) activation of protein kinase 1 by cAMP C) activation of protein kinase 2 by Ca2+ D) post-translational modification of existing proteins E) A, B, and C

D Topic: Concept 39.1 Skill: Application

6) In a signal transduction pathway, the transduction stage amplifies the original signal by A) involving more than one receptor molecule to receive the stimulus. B) having each receptor molecule produce multiple secondary messengers. C) having each secondary messenger activate numerous specific enzymes. D) B and C only E) A, B, and C

D Topic: Concept 39.1 Skill: Comprehension

1) The step(s) between a plant's perception of a change in the environment and the plant's response to that change is (are) best called A) a mutation. B) hormone production. C) pH change. D) signal transduction. E) an "all-or-none" response.

D Topic: Concept 39.1 Skill: Knowledge

11) Plants growing in a partially dark environment will grow toward light in a response called phototropism. Choose the incorrect statement regarding phototropism. A) It is caused by a chemical signal. B) One chemical involved is auxin. C) Auxin causes a growth increase on one side of the stem. D) Auxin causes a decrease in growth on the side of the stem exposed to light. E) Removing the apical meristem prevents phototropism.