Biology
Chapter 21: Plant Structure and Function
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1. A seed plant is held in the ground by its
a. stems.
b. roots.
c. leaves.
d. epidermis.
____
2. Ground tissue is found in a plant’s
a. stems only.
b. stems and leaves only.
c. roots and stems only.
d. roots, stems, and leaves.
____
3. In most plants, which organs are adapted to capture sunlight for photosynthesis?
a. roots
b. stems
c. leaves
d. flowers
____
4. In angiosperms, xylem consists of tracheids and
a. sieve tube elements.
b. companion cells.
c. vessel elements.
d. parenchyma.
____
5. If some of the xylem of a young oak tree were destroyed, it would most likely interfere with the
tree’s ability to
a. conduct sugars to the roots.
b. absorb sunlight.
c. absorb nutrients from the soil.
d. conduct water to the leaves.
____
6. Unlike tracheids, some vessel elements
a. die before they conduct water.
b. form a continuous tube.
c. are found in angiosperms.
d. are found in phloem.
____
7. Look at Figure 23–1. How would damage to structure B affect structure A?
a. The organelles in structure A would die.
b. Structure A would not be able to transport water.
c. Structure A would develop nuclei.
d. The openings in the ends of structure A would close.
____
8. Vascular tissue in plants consists of
a. meristems.
b. xylem and phloem.
c. parenchyma and collenchyma.
d. epidermis.
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Figure 23-1
____
9. The outer covering of a plant consists of
a. ground tissue.
b. vascular tissue.
c. dermal tissue.
d. meristematic tissue.
____ 10. To observe mitosis, which of the following should a student examine under a compound
microscope?
a. epidermis of a leaf
b. tip of a shoot
c. xylem from a tree trunk
d. phloem from the stem of a plant
____ 11. Which of the following are areas of unspecialized cells in which mitosis produces new cells that
are ready for differentiation?
a. parenchyma and collenchyma
b. meristems
c. xylem and phloem
d. epidermis
Figure 23–2
____ 12. In Figure 23–2, what letter indicates the tissue in which the products of photosynthesis are stored?
a. A
b. C
c. D
d. E
____ 13. Damage to which area of the root shown in Figure 23–2 will prevent the root from growing
longer?
a. A
b. C
c. F
d. H
____ 14. The layer of cells that encloses the vascular tissue in the central region of a root is the
a. endodermis.
b. cortex.
c. epidermis.
d. apical meristem.
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____ 15. The root cap is a tough structure that protects the
a. root hairs.
b. cortex.
c. meristem.
d. vascular cylinder.
____ 16. Mineral nutrients from the soil move into roots by
a. diffusion.
b. osmosis.
c. active transport.
d. root pressure.
____ 17. There is a one-way movement of water and minerals from the cortex into the vascular cylinder of
a root because
a. water molecules are in high concentration in the cortex.
b. nutrients are in low concentration in the cortex.
c. the root pressure is low.
d. the Casparian strip is waterproof.
____ 18. The soil around a lilac bush was watered with a solution containing radioactive phosphorus.
Several hours later, radiation was detected in its stems. Through which cells did the radioactive
phosphorus travel to the vascular cylinder?
a. sieve tube elements
b. companion cells
c. tracheids and vessel elements
d. cells of the cortex
____ 19. Root pressure
a. causes a plant’s roots to increase in size.
b. forces water in xylem downward.
c. is produced within the cortex of the root.
d. is produced in the vascular cylinder by active transport.
____ 20. One of the three main functions of stems is to
a. carry out photosynthesis.
b. carry water and nutrients between roots and leaves.
c. store carbohydrates.
d. store water.
____ 21. In a plant’s stem, the vascular tissue
a. is always arranged in rings of vascular bundles.
b. is continuous from the roots to the leaves.
c. carries nutrients up the stem but not down.
d. plays a role in photosynthesis and storage.
____ 22. Unlike roots, stems
a. transport water.
b. have ground tissue.
c. are protected by epidermal cells.
d. may play a part in photosynthesis.
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____ 23. Many cacti, such as saguaros and barrel cacti, have large stems and no leaves. What function of
leaves is taken on by the stems of such cacti?
a. They produce food by photosynthesis.
b. They absorb water and nutrients from the soil.
c. They transport materials throughout the plant.
d. They store excess water.
____ 24. One function of stems is to physically support leaves in a position to maximize photosynthesis. In
large trees, the support function of stems is primarily due to
a. phloem.
b. pith.
c. vascular cambium.
d. cork cambium.
____ 25. During primary growth, a stem
a. increases in length.
b. produces flowers.
c. increases in width.
d. produces wood.
____ 26. In dicots, secondary growth
a. changes primary xylem and phloem to secondary xylem and phloem.
b. makes the roots longer.
c. results from an increase in the primary xylem and phloem.
d. produces bark and wood.
____ 27. What might a thin tree ring indicate?
a. increased production of xylem
b. xylem production in winter
c. decreased production of phloem
d. a year of drought
____ 28. Which of the following describes the heartwood of a tree?
a. active xylem that transports water and minerals
b. old xylem that is no longer conducting water
c. old phloem that is no longer conducting nutrients
d. vascular cambium and cork cambium
____ 29. Oxygen and carbon dioxide move in and out of a leaf through the
a. palisade mesophyll.
b. guard cells.
c. phloem.
d. stomata.
____ 30. Most of the photosynthesis in plants takes place in the
a. mesophyll.
b. guard cells.
c. stomata.
d. xylem.
____ 31. The flat structure of a leaf blade enables its function as a photosynthetic organ by
a. decreasing the loss of oxygen into the atmosphere.
b. increasing the absorption of nutrients from soil.
c. protecting the rest of the plant from water loss due to evaporation.
d. exposing a greater surface area to capture energy from sunlight.
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Figure 23-3
____ 32. Look at Figure 23–3. Which letters indicate cells in which a large number of chloroplasts would
likely be found?
a. A and D
b. B and C
c. F and G
d. G and E
____ 33. In Figure 23–3, which letter points to the structure through which water is lost during
transpiration?
a. A
b. D
Underside of a Leaf
c. E
d. F
____ 34. In Figure 23–4, label X points to a
a. guard cell.
b. mesophyll cell.
c. vein.
d. stoma.
____ 35. In Figure 23–4, the water pressure in the
a. stoma is low.
b. stoma is high.
c. guard cells is high.
d. guard cells is low.
Figure 23-4
____ 36. The stomata of leaves are usually open
a. during the day if a plant has enough water.
b. during the day if a plant has too little water.
c. at night if a plant has enough water.
d. at night if a plant has too little water.
____ 37. In many plants, stomata are found only on the lower surface of the leaf. The most likely
explanation for this fact is that
a. photosynthesis only occurs in the spongy mesophyll near the bottom of the leaf.
b. stomata are closer to vascular bundles that bring water into the leaf.
c. gravity plays a role in gas exchange.
d. water loss would be less on the shaded lower surface than in direct sun.
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____ 38. Which of the following statements is true?
a. The opening of stomata decreases transpiration.
b. The stomata of a wilted plant are closed.
c. Oxygen cannot pass through stomata.
d. Stomata open only at night.
____ 39. The attraction of water molecules to other kinds of molecules is called
a. adhesion.
b. cohesion.
c. capillary action.
d. transpirational pull.
____ 40. Through which plant structure does water move by capillary action?
a. phloem
b. guard cells
c. mesophyll
d. xylem
____ 41. Water will move higher in a narrow glass tube than it will move in a wide glass tube because of
a. adhesion only.
b. capillary action.
c. pressure.
d. cohesion only.
____ 42. The closing of a plant’s stomata will
a. increase capillary action in the plant’s stem.
b. increase transpirational pull.
c. cause wilting.
d. cause less water to be pulled up from the plant’s roots.
____ 43. The movement of sugars in a plant can be explained by
a. capillary action.
b. transpirational pull.
c. the pressure-flow hypothesis.
d. root pressure.
____ 44. When a plant moves sugars from its leaves to its roots, the sink cells are in the
a. leaves.
b. roots.
c. stems.
d. chloroplasts.
____ 45. According to the pressure-flow hypothesis, which of the following statements is NOT true?
a. Water moves from the xylem to the phloem of a plant.
b. Water is necessary for sugars to move through phloem.
c. Phloem is able to move sugars in either direction to meet the nutritional needs of the plant.
d. The movement of water into a nutrient-rich region of the phloem decreases the pressure in
that region.
Modified True/False
Indicate whether the statement is true or false. If false, change the identified word or phrase to make the
statement true.
____ 16. In plants, the main organs in which photosynthesis takes place are leaves. ____________________
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____ 17. Phloem is made up of vessel elements and companion cells. _________________________
____ 18. Meristems produce new cells by mitosis. _________________________
____ 19. Root hairs are made up of ground tissue. _________________________
____ 20. The high concentration of mineral ions in the plant cells causes water molecules to move into the
plant by active transport. _________________________
____ 21. The area of a root through which water cannot pass is the epidermis. _________________________
____ 22. A bud contains ground tissue. _________________________
____ 23. The secondary growth of a dicot stem results from cell divisions in the stem’s vascular cambium and
xylem. _________________________
____ 24. In a tree, the heartwood is made up of older xylem that no longer conducts water. _______________
____ 25. The thin, flat part of a leaf is called the petiole. _________________________
____ 26. Transpiration from leaves occurs because of the osmosis of water from the leaf to the environment.
_________________________
____ 27. When the guard cells of a leaf lose water, the stomata open. _________________________
____ 28. In plants, the opening and closing of stomata balance water loss with the need for carbon dioxide.
_________________________
____ 29. Water rises to the top of a giant redwood tree by transpirational pull. _________________________
____ 30. When plants pump nutrients from their roots to their branches, the roots contain the sink cells.
_________________________
Completion
Complete each statement.
61. The three main organs of seed plants are roots, leaves, and ____________________.
62. In Figure 23–1, letter A indicates the ____________________, through which nutrients
move from cell to cell.
63. In xylem and phloem, the cells that keep their nuclei and organelles are the ______________.
64. _________________________ at the tips of stems and roots produce rapid growth in
plants.
65. In roots, ____________________ increase the surface area through which water and minerals
can diffuse.
67. As the relative concentration of mineral ions in a root’s cells increases, the osmosis of water Figure 23-1
molecules into the root ____________________.
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66. In Figure 23–5, structure B is the ____________________, which includes a waterproof zone called the
____________________.
68. The ____________________ on a stem contain apical meristems that can produce new stems and leaves.
69. During ____________________, cells in the apical meristems become longer, adding to the length of
roots and stems.
70. If a cross section of a tree has 12 tree rings, it is most likely ____________________ years old.
71. In conifers and dicots, the meristem that lies between the xylem and phloem is the __________________,
and the meristem that is part of the bark is the ________________________.
72. The air spaces in the _________________________ layer of a leaf connect with air through stomata in the
epidermis of the leaf.
73. ____________________ control the opening and closing of stomata.
74. Capillary action is a product of both __________________, which is the attraction of water molecules to
each other, and __________________, which is the attraction of water molecules to other kinds of molecules.
75. The _________________________ explains the movement of materials through phloem.
Short Answer
106. How is the function of a tree trunk related to photosynthesis?
107. Contrast the flow of materials in xylem and phloem.
108. Why are protective structures such as seed coats made up of sclerenchyma?
109. In which tissue of a plant would you expect to find the greatest number of new cells?
110. What three kinds of tissues do meristems develop into?
111. In Figure 23–5, what is structure C? Identify the tissues that make up this structure.
112. What do roots absorb from the soil?
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113. In what function do both roots and stems play a part?
114. A scientist discovers a new plant. She notes that the plant forms wood as it becomes taller. Did the
scientist discover a monocot or a dicot? Explain.
115. In what part of a leaf would you expect to find the greatest number of chloroplasts? Why?
116. During a very hot, sunny day, are stomata likely to be open or closed? Explain.
117. By what three processes does water rise from the roots to the top of a tree?
118. Root pressure causes guttation, which is the exuding of water droplets seen in the morning on blades of
grass and on the leaf edges of some monocots. Why does guttation not occur in the leaves of trees?
119. According to the pressure-flow hypothesis, how does water from xylem cause sugars to flow through
phloem?
120. In the pressure-flow hypothesis, what does the term sink cell refer to?
OTHER (Figures)
151. Use Models In Figure 23–6, which letters indicate structures that allow for the
secondary growth of the stem? Identify the structures.
152. Classify Which labels in Figure 23–6 indicate ground tissue? Identify
the cell types that might be found in ground tissue.
153. Predict In Figure 23–6, how does growth in the tissues labeled H and
G affect the stem?
154. Compare and Contrast Which label in Figure 23–6 indicates cells that are secondary
growth tissues, B or C? Identify the tissues.
155. Use Models Which structures in Figure 23–6 were formed by primary growth?
What are they called?
156. Use Models Which four structures in Figure 23–3 protect the
leaf from drying out? Identify the structures.
157. Interpret Visuals In Figure 23–3, which letter represents
a structure whose tissues lack chlorophyll? What is the structure
called?
158. Interpret Visuals Are the stomata in the leaf in
Figure 23–3 open or closed? Identify the letter of the stoma.
159. Draw Conclusions What is the importance of the spaces
between the cells labeled C in Figure 23–3?
160. Interpret Visuals In Figure 23–3, what is structure F? What two types
of tissues make up this structure?
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161. Interpret Visuals What do the arrows in Figure 23–7 represent?
162. Infer What process is helping to move water upward through part A of Figure 23–7?
163. Infer In part C of Figure 23–7, what process is helping to bring water to the top of the plant?
164. Infer In Figure 23–7, what process causes water to move upward in part B of the plant?
165. Infer What kind of vascular tissue is involved in the processes shown in Figure 23–7?
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ANSWER KEY
MULTIPLE CHOICE
1.
ANS: B
2.
ANS: D
3.
ANS: C
4.
ANS: C
5.
ANS: D
6.
ANS: B
7.
ANS: A
8.
ANS: B
9.
ANS: C
10. ANS: B
11. ANS: B
12. ANS: B
13. ANS: D
14. ANS: A
15. ANS: C
16. ANS: C
17. ANS: D
18. ANS: D
19. ANS: D
20. ANS: B
21. ANS: B
22. ANS: D
23. ANS: A
24. ANS: C
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25. ANS: A
26. ANS: D
27. ANS: D
28. ANS: B
29. ANS: D
30. ANS: A
31. ANS: D
32. ANS: B
33. ANS: C
34. ANS: D
35. ANS: C
36. ANS: A
37. ANS: D
38. ANS: B
39. ANS: A
40. ANS: D
41. ANS: B
42. ANS: D
43. ANS: C
44. ANS: B
45. ANS: D
MODIFIED TRUE/FALSE
16. ANS: T
17. ANS: F, sieve tube
18. ANS: T
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19. ANS: F, dermal
20. ANS: F, osmosis
21. ANS: F Casparian strip endodermis
22. ANS: F, apical meristems
23. ANS: F, cork cambium
24. ANS: T
25. ANS: F, blade
26. ANS: F, evaporation
27. ANS: F, close
28. ANS: T
29. ANS: T
30. ANS: F, branches
COMPLETION
61. ANS: stems
62. ANS: sieve tube elements
63. ANS: companion cells
64. ANS: Meristems
65. ANS: root hairs
67. ANS: increases
66. ANS: endodermis, Casparian strip
68. ANS: buds
69. ANS: primary growth
70. ANS: 12
71. ANS: vascular cambium, cork cambium
72. ANS: spongy mesophyll
73. ANS: Guard cells
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74. ANS: cohesion, adhesion
75. ANS: pressure-flow hypothesis
SHORT ANSWER
106. ANS: The xylem in a tree trunk carries water from the roots to the leaves. The water is used for
photosynthesis. The tree trunk carries the carbohydrates produced during photosynthesis from the leaves to
other parts of the plant.
107. ANS: Through the xylem, water moves only upward into the plant. Through the phloem, carbohydrates
and other materials can move both upward and downward.
108. ANS: Sclerenchyma is a type of ground tissue in which cells have extremely thick and rigid cell walls.
This makes sclerenchyma the ideal material for a seed coat, which protects a developing embryo.
109. ANS: The greatest number of new cells are found in the meristems.
110. ANS: Meristems develop into dermal, vascular, and ground tissues.
111. ANS: Structure C is the vascular cylinder, which is made of xylem and phloem.
112. ANS: Roots absorb water and dissolved nutrients from the soil.
113. ANS: Both roots and stems transport substances.
114. ANS: The plant forms wood, which results from secondary growth. Monocots rarely go through
secondary growth, so the scientist likely discovered a dicot.
115. ANS: The mesophyll would have the greatest number of chloroplasts. Photosynthesis occurs in this part
of the leaf.
116. ANS: On a hot sunny day, stomata will most likely be closed because the plant will need to conserve
water
117. ANS: Water rises from the roots to the top of a tree by root pressure, capillary action, and transpirational
pull.
118. ANS: Guttation does not occur in the leaves of trees because root pressure alone cannot force water high
enough to reach the leaves.
119. ANS: When sugars are pumped into phloem, water moves by osmosis from xylem into the phloem,
increasing the pressure in the phloem. The increased pressure forces the sugars through the phloem.
120. ANS: Sink cells are places in a plant where sugars are used or stored.
OTHER (Figures)
151. ANS: Label G indicates the vascular cambium and label H indicates the cork cambium. Together, these
two meristems allow for the secondary growth of the stem.
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152. ANS: Label A indicates cortex and label F indicates pith; both are parenchyma, a type of ground tissue.
Ground tissue can be parenchyma, collenchyma, or sclerenchyma.
153. ANS: Labels H and G indicate meristems. Growth in these two areas makes the stem wider.
154. ANS: Label C points to secondary phloem and label B points to primary phloem. Label C points to the
secondary growth tissues.
155. ANS: Labels A, B, E, and F indicate structures that were formed by primary growth. Label A indicates
the cortex, B indicates the primary phloem, E indicates the primary xylem, and F indicates the pith.
156. ANS: Structure A, the cuticle, and structure D, the epidermis, protect the leaf from drying out. Structure
E, the stoma, and structure G, the guard cells, also play roles in conserving water
157. ANS: Structure F is a leaf vein; its tissues, xylem and phloem, lack chlorophyll.
158. ANS: The stomata, one of which is indicated by letter E, are open.
159. ANS: The spaces connect with the stomata, allowing gases to be exchanged between the mesophyll cells
and the atmosphere.
160. ANS: Structure F is a leaf vein, which includes xylem and phloem.
161. ANS: The arrows represent the movement of water through a plant.
162. ANS: Root pressure is helping to move water upward through part A.
163. ANS: Transpiration is helping to bring water to the top of the plant.
164. ANS: Capillary action causes water to move upward in part B.
165. ANS: Xylem tissue transports water through a plant.
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