Plants that are thousands of years old have

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

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

3. In the meristem regions of plants, you would expect to find • inactive cells. • dividing cells. • companion cells. • reproductive cells.

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

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

6. Plant hormones are produced in • the buds of flowers. • flowers in full bloom. • old leaves. • roots.

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

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

9. 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.

10. What type of hormone affects plant growth and the development of fruits? • auxin • cytokinin • gibberellin • ethylene

11. What is the source of ethylene gas in a plant? • leaf buds • root hairs • fruit tissues • lateral meristems

12. Powerful synthetic auxins are sometimes used as • fertilizers. • herbicides. • insecticides. • fruit ripeners.

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.

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.

15. The responses of plants to external stimuli are called • tropisms. • auxins. • gibberellins. • cytokinins.

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

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.

18. The growth patterns of plants such as ivy and pole beans are regulated by • gravitropism. • phototropism. • thigmotropism. • all of the above

19. Roots growing with gravity and stems growing against gravity are examples of • gravitropism. • phototropism. • thigmotropism. • photoperiodism.

20. The growth of plant seedlings is usually • phototropic and gravitropic. • thigmotropic and gravitropic. • phototropic and influenced by ethylene. • gravitropic and influenced by ethylene.

21. The closing of the leaves of a Venus’ flytrap is called • a stimulus. • phototropism. • a rapid response. • a hormonal response.

22. Phytochrome is a pigment that controls • bud scaling. • gravitropism. • photosynthesis. • photoperiodism.

23. Flowering in many plants is dependent on the • amount of daily rainfall. • average daily temperatures. • length of uninterrupted daylight. • length of uninterrupted darkness.

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.

25. The response of a plant to changes in the length of day or night is called • abscission. • thigmotropism. • photosynthesis. • photoperiodism.

26. What is a pigment that regulates the changes in activity that prepare plants for winter? • cytokinin • meristem • ethylene • phytochrome

27. What hormones influence the shedding of leaves? • auxin and ethylene • cytokinin and phytochrome • gibberellin and auxin • phytochrome and gibberellin

28. Which substance helps a plant resist low temperatures? • auxin • cytokinin • gibberellin • phytochrome

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.

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.

31. A period of decreased activity in a plant is called • dormancy. • propagation. • germination. • reproduction.

32. 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.

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.

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.

35. 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.

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.

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.

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.

39. Plants that get their water and nutrients directly from a host plant are • epiphytes. • carnivorous plants. • xerophytes. • parasites.

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.

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.

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.

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

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.

45. A drug in tobacco that might be a natural insecticide protecting the tobacco plants is • nicotine. • codeine. • aspirin. • ethylene.

46. Plants have enzymes that direct, control, and regulate their growth. _________________________ • True • False

47. Meristems control the development of specialized tissues in plants. _________________________ • True • False

48. Target cells must contain a receptor in order to respond to a hormone. _________________________ • True • False

49. Growth in lateral branches of a plant is stimulated by ethylene. _________________________ • True • False

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