1. Plants that are thousands of years old have
no meristems.
a rigid body organization.
the ability to continue growing.
predetermined growth patterns. 1 2 3 4 5

2. The regions of tissue in a plant that produce cells that later become specialized tissues are the
roots.
stems.
leaves.
meristems. 1 2 3 4 5

3. In the meristem regions of plants, you would expect to find
inactive cells.
dividing cells.
companion cells.
reproductive cells. 1 2 3 4 5

4. Plants can respond to changing environmental conditions by the use of which chemicals?
sugars
enzymes
pigments
hormones 1 2 3 4 5

5. Which substance(s) produced in one part of a plant affect(s) another part?
oxygen and nitrogen
enzymes
herbicides
hormones 1 2 3 4 5

6. Plant hormones are produced in
the buds of flowers.
flowers in full bloom.
old leaves.
roots. 1 2 3 4 5

7. Which of the following best describes plant hormones?
chemical messengers only
growth regulators only
enzymes, growth regulators, and chemical messengers
growth regulators and chemical messengers 1 2 3 4 5

8. Which of the following is NOT a function of auxins?
promoting apical dominance
promoting cell elongation in stems
promoting the growth of lateral buds
promoting the production of ethylene 1 2 3 4 5

9. auxins. ethylenes. cytokinins. gibberellins.
Hormones that stimulate cell elongation and are produced in the rapidly growing region near the tip of the plant’s root or stem are called
auxins.
ethylenes.
cytokinins.
gibberellins. 1 2 3 4 5

10. What type of hormone affects plant growth and the development of fruits?
auxin
cytokinin
gibberellin
ethylene 1 2 3 4 5

11. What is the source of ethylene gas in a plant?
leaf buds
root hairs
fruit tissues
lateral meristems 1 2 3 4 5

12. Powerful synthetic auxins are sometimes used as
fertilizers.
herbicides.
insecticides.
fruit ripeners. 1 2 3 4 5

13. Cytokinins differ from auxins in that cytokinins
cause leaves to fall.
inhibit lateral bud growth.
inhibit elongation of cells.
cause seeds to remain dormant. 1 2 3 4 5

14. If the apical meristem of a mature plant is removed, the plant will most likely
lose its ability to move phototropically.
show a dramatic and rapid increase in height.
develop apical dominance and begin to flower.
lose apical dominance and grow lateral branches. 1 2 3 4 5

15. The responses of plants to external stimuli are called
tropisms.
auxins.
gibberellins.
cytokinins. 1 2 3 4 5

16. What is the phenomenon that is causing the bean seedling to bend in Figure 25–1?
gravitropism
phototropism
rapid response
leaf abscission 1 2 3 4 5

17. Gravitropism ensures that the plant in Figure 25–1 will
grow roots into the soil.
drop its leaves in the winter.
make green and yellow pigments.
have shoots that grow toward the soil. 1 2 3 4 5

18. The growth patterns of plants such as ivy and pole beans are regulated by
gravitropism.
phototropism.
thigmotropism.
all of the above 1 2 3 4 5

19. Roots growing with gravity and stems growing against gravity are examples of
gravitropism.
phototropism.
thigmotropism.
photoperiodism. 1 2 3 4 5

20. The growth of plant seedlings is usually
phototropic and gravitropic.
thigmotropic and gravitropic.
phototropic and influenced by ethylene.
gravitropic and influenced by ethylene. 1 2 3 4 5

21. The closing of the leaves of a Venus’ flytrap is called
a stimulus.
phototropism.
a rapid response.
a hormonal response. 1 2 3 4 5

22. Phytochrome is a pigment that controls
bud scaling.
gravitropism.
photosynthesis.
photoperiodism. 1 2 3 4 5

23. Flowering in many plants is dependent on the
amount of daily rainfall.
average daily temperatures.
length of uninterrupted daylight.
length of uninterrupted darkness. 1 2 3 4 5

24. A commercial flower grower could induce winter flowering of a long-day plant by
fertilizing the plant with nitrogen.
treating the plant with gibberellin.
covering the plant with an opaque cloth in the late afternoon.
exposing the plant to a brief period of light in the middle of the night. 1 2 3 4 5

25. The response of a plant to changes in the length of day or night is called
abscission.
thigmotropism.
photosynthesis.
photoperiodism. 1 2 3 4 5

26. What is a pigment that regulates the changes in activity that prepare plants for winter?
cytokinin
meristem
ethylene
phytochrome 1 2 3 4 5

27. What hormones influence the shedding of leaves?
auxin and ethylene
cytokinin and phytochrome
gibberellin and auxin
phytochrome and gibberellin 1 2 3 4 5

28. Which substance helps a plant resist low temperatures?
auxin
cytokinin
gibberellin
phytochrome 1 2 3 4 5

29. One way that plants react to seasonal changes is by
forming abscission layers.
trapping insects for nitrogen.
producing more chlorophyll.
growing oxygen tubes to their roots. 1 2 3 4 5

30. The brilliant colors of leaves in the fall are a result of
new synthesis of orange and yellow pigments in leaves.
the movement of chlorophyll from the stems to the leaves.
the stopping of chlorophyll synthesis, making the carotenoid pigments visible.
the decrease of auxins in the meristems and the increase of phytochrome in the leaves. 1 2 3 4 5

31. A period of decreased activity in a plant is called
dormancy.
propagation.
germination.
reproduction. 1 2 3 4 5

32. produces thick, green stems. produces seeds when it rains.
The prickly-pear cactus shown in Figure 25–2 has a leaf adaptation that
pumps out salt.
reduces water loss.
produces thick, green stems.
produces seeds when it rains. 1 2 3 4 5

33. How is the cactus in Figure 25–2 adapted to soak up rare rainfall quickly?
It has thin, sharp spines.
It has stems that shrivel when it rains.
It has wide stems that catch rainwater.
It has an extensive shallow root system. 1 2 3 4 5

34. How is the cactus in Figure 25–2 adapted to survive long dry periods?
Its stems swell and store water.
Its leaves drop off when it gets dry.
Its root system holds water for later use.
It remains dormant when there is no rain. 1 2 3 4 5

35. It has an adaptation to pump salt out of plant tissues.
Spartina grass is a plant that grows in salt marshes. What adaptation can you assume spartina grass has that allows it to survive in salty water?
It has an adaptation to pump salt out of plant tissues.
Its roots selectively exclude salt from the water it takes in.
It is adapted to using salt as a nutrient instead of phosphorus.
It grows new roots quickly to replace those burned by high salt concentrations. 1 2 3 4 5

36. Aquatic plants that grow in mud that has little or no oxygen have adaptations that
allow them to survive without oxygen.
keep them from taking in too much water.
let them photosynthesize below the surface of the water.
help them diffuse oxygen from the surface down to their roots. 1 2 3 4 5

37. Bald cypress trees have “knees” that function to
support the tree in the mud.
bring oxygen down to the roots.
produce seeds that float in water.
photosynthesize in the deep shade. 1 2 3 4 5

38. A carnivorous plant obtains nitrogen
directly from the air.
through its roots from the soil.
by trapping and digesting insects.
by extracting it from a host plant. 1 2 3 4 5

39. Plants that get their water and nutrients directly from a host plant are
epiphytes.
carnivorous plants.
xerophytes.
parasites. 1 2 3 4 5

40. The dodder plant Cuscuta, which is a parasite,
helps the plant on which it grows.
gathers its own water and nutrients.
harms the plant on which it grows.
captures small organisms to meet its nutritional needs. 1 2 3 4 5

41. Epiphytes differ from parasites in that epiphytes
harm their host plants.
grow directly on the bodies of other plants.
extract water from their host plants.
produce their own food. 1 2 3 4 5

42. Carnivorous plants obtain the nitrogen they need from insects because
they are insect parasites.
bacteria in the soil use up all the available nitrogen.
there is little or no nitrogen in the soil where these plants live.
insects release more nitrogen than can be obtained from normal soil. 1 2 3 4 5

43. The tobacco plant produces a chemical that
is probably a natural insecticide.
protects the plant from insects.
affects the human nervous system.
all of the above 1 2 3 4 5

44. Which is NOT true of the chemical defenses produced by plants?
They can act as insect repellants.
They can be used as food by plants.
They can be poisonous and bad-tasting.
They can be used by humans as medicines. 1 2 3 4 5

45. A drug in tobacco that might be a natural insecticide protecting the tobacco plants is
nicotine.
codeine.
aspirin.
ethylene. 1 2 3 4 5

46. Plants have enzymes that direct, control, and regulate their growth
True
False 1 2 3 4 5

47. Meristems control the development of specialized tissues in plants
True
False 1 2 3 4 5

48. Target cells must contain a receptor in order to respond to a hormone
True
False 1 2 3 4 5

49. Growth in lateral branches of a plant is stimulated by ethylene
True
False 1 2 3 4 5

50. Cells on the shaded side of a stem elongate more than cells on the side receiving light because of the hormone ethylene. _________________________
True
False 1 2 3 4 5

51. Seedlings finding their way out of the soil and into the sunlight is an example of photoperiodism. _________________________
True
False 1 2 3 4 5

52. The growing tip of a climbing vine exhibits phototropism when it grows in a circling motion. _________________________
True
False 1 2 3 4 5

53. Long-day plants flower when nights are long. _________________________
True
False 1 2 3 4 5

54. Photoperiodism in plants is regulated by ethylene, which times seasonal activities such as flowering and growth. _________________________
True
False 1 2 3 4 5

55. The critical day length for a plant indicates the number of hours of darkness a plant requires to produce flowers. _________________________
True
False 1 2 3 4 5

56. The orange and yellow colors of fall leaves are a result of the reduction of chlorophyll in the leaf, revealing the phytochrome pigments. _________________________
True
False 1 2 3 4 5

57. Angiosperms have been modified over time to survive in various environments through the process of natural selection. _________________________
True
False 1 2 3 4 5

58. In some desert plants, a tuber is a stem that is specialized to store water. _________________________
True
False 1 2 3 4 5

59. Some plant chemicals act as insect hormones, changing the way an insect normally develops. _________________________
True
False 1 2 3 4 5

60. Many plants produce chemical compounds that ward off potential pollinators. _________________________
True
False 1 2 3 4 5

61. Participant Scores Participant 1 Participant 2 Participant 3
Participant 1
Participant 2
Participant 3
Participant 4
Participant 5

62. ____________________ are the source of plant growth, which is then controlled and regulated by hormones. 1 2 3 4 5
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63. Plants can respond to changing environmental conditions by the use of ____________________.1 2 3 4 5
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64. A target cell must contain a hormone ____________________ to which the hormone can bind.1 2 3 4 5
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65. Fruit ripening can be stimulated by ____________________.1 2 3 4 5
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66. Very high concentrations of auxins in roots inhibit the ____________________ of root cells.1 2 3 4 5
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67. Figure 25–1

68. In Figure 25–1, the bean seedling’s roots emerge from the top of the seed, then curve around and grow down. This plant response is called ____________________. 1 2 3 4 5
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69. The ability of the young seedling in Figure 25–1 to turn toward the light in just a few hours is called ____________________. 1 2 3 4 5
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70. Plant responses to external stimuli are called ____________________, from a Greek word meaning “turning.” 1 2 3 4 5
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71. As cold weather approaches, ____________________ plants turn off photosynthetic pathways.1 2 3 4 5
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72. Phytochrome is a ____________________ in plants that produces responses to changing day lengths with seasonal changes. 1 2 3 4 5
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73. Mangroves survive in oxygenless mud by growing specialized ____________________ that have air spaces in them. 1 2 3 4 5
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74. Some desert plants are adapted for flowering and producing ____________________ quickly after a rainfall. 1 2 3 4 5
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75. A desert plant that is transplanted to an aquatic environment likely would not survive because it is not ____________________ to that environment. 1 2 3 4 5
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76. A plant that grows in fresh water would not survive in salt water because its leaves do not have specialized ____________________ to pump out salt, as do salt-tolerant plants. 1 2 3 4 5
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77. Insect predators have provided the adaptive pressure over time for plants to develop ____________________ defenses to avoid being eaten. 1 2 3 4 5
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78. List two environmental factors to which plants respond.1 2 3 4 5
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79. Explain what is meant by the phrase “forever young” with regard to most plants.1 2 3 4 5
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80. What is a plant hormone? 1 2 3 4 5
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81. What did Charles and Francis Darwin demonstrate in their experiment with oat seedlings?1 2 3 4 5
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82. Explain how auxin-influenced gravitropism causes the roots of a seedling to grow around an obstacle.1 2 3 4 5
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83. From what you know about a plant’s response to touch, explain why a rapid response is more advantageous to a Venus’ flytrap than a thigmotropic response. 1 2 3 4 5
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84. How do commercial growers supply blooming chrysanthemums, carnations, and roses to flower shops all year long? 1 2 3 4 5
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85. Why do hollyhocks that are planted outside bloom only in the summer?1 2 3 4 5
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86. What three major changes do plants undergo in the fall in preparation for winter dormancy?1 2 3 4 5
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87. What is an abscission layer?1 2 3 4 5
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88. Describe the particular problems of carnivorous plants in obtaining nitrogen from the soil.1 2 3 4 5
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89. Figure 25–2

90. How is the cactus in Figure 25–2 adapted to prevent water loss through transpiration?1 2 3 4 5
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91. How are epiphytes similar to and different from parasites?1 2 3 4 5
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92. How are some of the chemical defenses of plants beneficial to humans?1 2 3 4 5
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93. How might the mangrove’s adaptation for getting rid of salt help defend it against plant-eating animals? 1 2 3 4 5
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94. Contrast the growth patterns of animals with those of plants.1 2 3 4 5
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95. Explain how different cells can react differently when exposed to the same hormone.1 2 3 4 5
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96. Explain why sealing fruit in a bag might cause the fruit to ripen quickly.1 2 3 4 5
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97. Briefly describe how plants respond to light and gravity.1 2 3 4 5
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98. What happens to a plant when a gardener snips off the growing tip?1 2 3 4 5
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99. Summarize the relationship between phytochrome and photoperiodism in flowering plants.1 2 3 4 5
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100. Explain the survival advantage to plants of becoming dormant in winter.1 2 3 4 5
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101. Describe the seed adaptations you might find in some aquatic plants.1 2 3 4 5
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102. How are waterlilies adapted to growing in mud without oxygen?1 2 3 4 5
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103. Describe the adaptation for obtaining nutrients that pitcher plants and parasitic plants have in common. 1 2 3 4 5
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