Ch 36 Flashcards


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1

1) Given that early land plants most likely share a common ancestor with green algae, the earliest land plants were most likely ________.
A) nonvascular plants that grew leafless, photosynthetic shoots
B) species that did not exhibit alternation of generations

C) vascular plants with well-defined root systems

D) plants with well-developed leaves

A

2

2) A fellow student brought in a leaf to be examined. The leaf was dark green, thin, had stoma on the lower surface only, and had a total surface area of ten square meters. Where is the most likely environment where this leaf was growing?
A) a large, still pond

B) a tropical rain forest
C) an oasis within a grassland
D) the floor of a deciduous forest

B

3

3) Phloem sap can flow ________.
A) from leaves to shoots only
B) from shoots to leaves only
C) from sites of sugar production to storage units only

D) both ways between production and storage sites

D

4

4) Why do most angiosperms have alternate phyllotaxy, with leaf emergence at an angle of 137.5° compared to leaves above and below?
A) to allow maximum exposure to light
B) to promote a leaf area index above 8

C) to reduce shading of lower leaves
D) to allow maximum exposure to light and to reduce shading of lower leaves

D

5

5) A plant developed a mineral deficiency after being treated with a fungicide. What is the most probable cause of the deficiency?
A) Mineral receptor proteins in the plant membrane were not functioning.
B) Mycorrhizal fungi were killed.

C) Active transport of minerals was inhibited.
D) The genes for the synthesis of transport proteins were destroyed.

B

6

6) Which one of the following does not correctly match the form with its function?

A) stem—water and minerals are transported upward
B) xylem sap—transport water and nutrients from roots to shoots upward
C) transpiration—loss of water mostly through stomata

D) cork cambium—increase in stem thickness

D

7

7) The leaf area index is the ratio of the ________.
A) upper leaf surface of a single plant divided by the surface area of the land on which the plant grows
B) lower leaf surface of a single plant divided by the surface area of the land on which the plant grows
C) upper leaf surface of a single plant multiplied by the surface area of the land on which the plant grows
D) lower leaf surface of a single plant multiplied by the surface area of the land on which the plant grows

A

8

8) Which one of the following played a critical role in the successful colonization of land by plants?
A) ground tissue
B) bacterial association

C) mycorrhizae
D) cuticle on leaf surface

C

9

9) Which structure or compartment is separate from the apoplastic route?

A) the lumen of a xylem vessel
B) the lumen of a sieve tube
C) the cell wall of a mesophyll cell

D) the cell wall of a root hair

B

10

10) The apoplast in plant tissues consists of ________.
A) cell walls, extracellular spaces, and plasmodesmata
B) cell walls, extracellular spaces, and vessel elements
C) vessel elements, plasmodesmata, and extracellular spaces

D) cell walls, plasma membrane, and cytosol

B

11

11) Active transport of amino acids in plants at the cellular level requires ________.

A) NADP and channel proteins
B) xylem membranes and channel proteins
C) sodium/potassium pumps and xylem membranes

D) ATP, transport proteins, and a proton gradient

D

12

12) The physical property that predicts the direction of water flow is referred as ________.

A) potassium pump
B) water potential
C) osmotic potential

D) sodium pump

B

13

13) What is the function of proton pumps localized in the plant plasma membrane?

A) to transfer phosphorus groups from ATP to proteins
B) to transfer metal ions across the plasma membrane
C) to transfer anions across the plasma membrane

D) to create a membrane potential

D

14

14) Which of following ions play the primary role in basic transport processes in plant cells?

A) H+
B) Na+
C) K+

D) Ca+2

A

15

15) Which of the following would be least likely to affect osmosis in plants?

A) a difference in solute concentrations
B) receptor proteins in the membrane
C) aquaporins

D) a difference in water potential

B

16

16) The movement of water across biological membranes can best be predicted by ________.

A) prevailing weather conditions
B) aquaporins
C) level of active transport

D) water potentials

D

17

17) If isolated plant cells with a water potential averaging -0.5 MPa are placed into a solution with a water potential of -0.3 MPa, which of the following would be the most likely outcome?

A) The pressure potential of the cells would increase.
B) Water would move out of the cells.

C) The cell walls would rupture, killing the cells.

D) Solutes would move out of the cells.

A

18

18) Solute potential in a cell is also called ________.

A) water potential
B) osmotic potential
C) potential gradient

D) pressure potential

B

19

19) The value for Ψ in root tissue was found to be -0.15 MPa. If you take the root tissue and place it in a 0.1 M solution of sucrose (Ψ = -0.23 MPa), the net water flow would ________.

A) be from the tissue into the sucrose solution
B) be from the sucrose solution into the tissue

C) be in both directions, and the concentration of water would remain equal

D) be impossible to determine from the values given here

A

20

20) In the transmembrane route for transport within plant tissue, ________.
A) water and solutes move out of one cell, across the cell wall, and into the neighboring cell
B) water and solutes move out of one cell, through the plasmodesmata, and into the neighboring cell
C) water moves out of one cell, across the cell wall, and into the neighboring cell
D) solutes move out of one cell, across the plasmodesmata, and into the neighboring cell

A

21

21) When an animal cell is placed in a hypotonic solution and water enters the cell via osmosis, the volume of the cell increases until it bursts. This does not happen to plant cells, because ________.
A) they have large central vacuoles, which provide abundant space for storage of incoming water

B) they have cell walls, which prevent the entry of water by osmosis

C) they have cell walls, which provide pressure to counteract the pressure of the incoming water

D) certain gated channel proteins embedded in their plasma membranes open as osmotic pressure decreases, allowing excess water to leave the cell

C

22

22) How does a flaccid cell differ from a turgid cell?

A) A flaccid cell has higher pressure potential.
B) A flaccid cell has lower pressure potential.
C) A flaccid cell has higher solute potential.

D) A flaccid cell has lower solute potential.

B

23

23) The protoplast consists of ________.
A) all cell components without a nucleus
B) all cell components without a cell membrane
C) only the cytoplasm and nucleus
D) the living part of the cell, including the cell membrane

D

24

24) Compared to a cell with few aquaporins in its membrane, a cell containing many aquaporins will ________.
A) have a faster rate of osmosis
B) have a lower water potential

C) have a higher water potential
D) have a faster rate of active transport

A

25

25) If you place flaccid plant cells in pure water, water ________ into cell because it has ________.
A) does not enter the cell; solutes and low water potential
B) enter the cell; solutes and low water potential

C) enter the cell; solutes and high water potential
D) does not enter the cell; solutes and high water potential

B

26

26) If ΨP = 0.3 MPa and ΨS = -0.45 MPa, the resulting Ψ is ________. A) +0.75 MPa
B) -0.75 MPa
C) -0.15 MPa

D) +0.15 MPa

C

27

27) Which of the following are important components of the long-distance transport process in plants?

  1. I) the cohesion of water molecules
  2. II) a negative water potential
  3. III) the root parenchyma
  4. IV) the active transport of solutes
  5. V) bulk flow from source to sink

A) II, III, IV, and V
B) I, III, IV, and V
C) I, II, IV, and V
D) I, II, III, and V

C

28

28) The value for Ψ in root tissue was found to be -0.15 MPa. If you take the root tissue and place it in a 0.1 M solution of sucrose (Ψ = -0.23 MPa), the net water flow would ________.

A) be from the tissue into the sucrose solution
B) be from the sucrose solution into the tissue

C) be in both directions and the concentrations would remain equal

D) occur only as ATP was hydrolyzed in the tissue

A

29

29) Loss of water from the aerial parts of plants is called ________.

A) dehydration
B) respiration
C) gas exchange

D) transpiration

D

30

30) Which of the following contribute to the surface area available for water absorption from the soil by a plant root system?

I) root hairs
II) endodermis
III) mycorrhizae
IV) fibrous arrangement of the roots

A) II and III
B) I, III, and IV
C) I, II, and IV
D) I, II, III, and IV

B

31

31) What is the overall charge on the cytoplasmic side of a plant cell plasma membrane?

A) positive
B) negative
C) neutral

B

32

32) A water molecule could move all the way through a plant from soil to root to leaf to air and pass through a living cell only once. This living cell would be a part of which structure?
A) a guard cell
B) the root epidermis

C) the endodermis
D) the root cortex

C

33

33) Bulk flow is much faster than diffusion or active transport. Peak velocities in the transport of xylem sap can range from ________ for trees with wide vessel elements.
A) 10-20 m/hr
B) 15-45 m/hr

C) 5-10 m/hr
D) >50 m/hr

B

34

34) In plant roots, the Casparian strip ________.
A) aids in the uptake of nutrients
B) provides energy for the active transport of minerals into the stele from the cortex
C) ensures that all minerals are absorbed from the soil in equal amounts
D) ensures that all water and dissolved substances must pass through a cell membrane before entering the stele

D

35

35) Which of the following observations provides the strongest evidence against root pressure being the principal mechanism of water transport in the xylem?
A) Not all soils have high concentrations of ions.
B) Root pressure requires movement of water into the xylem from surrounding cells in the roots.

C) Over long distances, the force of root pressure is not enough to overcome the force of gravity.

D) There is no water potential gradient between roots and shoots.

C

36

36) One is most likely to see guttation in small plants when the ________.

A) transpiration rates are high
B) root pressure exceeds transpiration pull
C) preceding evening was hot, windy, and dry

D) roots are not absorbing minerals from the soil

B

37

37) Most of the water taken up by a plant is ________.

A) used as a solvent
B) used as a hydrogen source in photosynthesis
C) lost during transpiration

D) used to keep cells turgid

C

38

38) Transpiration in plants requires ________.

  1. I) adhesion of water molecules to cellulose
  2. II) cohesion between water molecules
  3. III) evaporation of water molecules
  4. IV) active transport through xylem cells
  5. V) transport through tracheids

A) I, III, IV, and V
B) I, II, IV, and V
C) I, II, III, and V
D) I, II, III, and IV

C

39

39) During the nighttime, due to lack of transpiration, the water potential within the vascular cylinder ________.
A) lowers due to accumulation of minerals
B) increases due to accumulation of minerals

C) lowers due to loss of minerals
D) increases due to loss of minerals

A

40

40) What is the main force by which most of the water within xylem vessels moves toward the top of a tree?
A) active transport of ions into the stele
B) evaporation of water through stoma

C) the force of root pressure
D) osmosis in the root

B

41

41) Water potential is generally most negative in which of the following parts of a plant?

A) mesophyll cells of the leaf
B) xylem vessels in leaves
C) xylem vessels in roots

D) cells of the root cortex

A

42

42) Formation of the curved upper surface, such as occurs in a tube filled with water, is an important factor in plant water movement. A curved upper surface is created by ________.

A) the upward pull of gravity on the water column in the tube
B) downward pressure from the atmosphere on the topmost layer of water molecules

C) the water molecules being pulled upward by adhesion to the air
D) the topmost layer of water molecules being pulled downward by the hydrogen bonds to the water molecules below

D

43

43) Which one of the following ions plays a critical role in the opening and closing of stomata?

A) H+
B) Na+
C) K+

D) Ca+2

C

44

44) Which of the following primarily enters a plant somewhere other than through the roots?

A) carbon dioxide
B) nitrogen
C) potassium

D) water

A

45

45) The opening of stomata is thought to involve ________.

A) an increase in the solute concentration of the guard cells

B) active transport of water out of the guard cells
C) decreased turgor pressure in guard cells

D) movement of K+ from the guard cells

A

46

46) The high surface-to-volume ratio in leaves aids in ________. A) more light absorption
B) less light absorption
C) CO2 absorption

D) transpiration

C

47

47) Ignoring all other factors, what kind of day would result in the fastest delivery of water and minerals to the leaves of an oak tree?
A) a cool, dry day
B) a very hot, dry, windy day

C) a warm, humid day
D) a cool, humid day

B

48

48) Photosynthesis ceases when leaves wilt, mainly because ________.

A) the chlorophyll in wilting leaves is degraded
B) flaccid mesophyll cells are incapable of photosynthesis
C) stomata close, preventing carbon dioxide from entering the leaf

D) accumulation of carbon dioxide in the leaf inhibits enzymes

C

49

49) The water lost during transpiration is a side effect of the plant's exchange of gases. However, the plant derives some benefit from this water loss in the form of ________.
A) increased turgor and increased growth
B) mineral transport and increased growth

C) evaporative cooling and increased turgor
D) evaporative cooling and mineral transport

D

50

50) Which of the following experimental procedures would most likely reduce transpiration while allowing the normal growth of a plant?
A) subjecting the leaves of the plant to a partial vacuum
B) increasing the level of carbon dioxide around the plant

C) putting the plant in drier soil
D) decreasing the relative humidity around the plant

B

51

51) Several tomato plants are growing in a small garden plot. If soil water potential were to drop significantly on a hot, summer afternoon, which of the following would most likely occur?
A) Size of stomatal openings would decrease.
B) Transpiration would increase.

C) The leaves would become more turgid.
D) The uptake of carbon dioxide would be enhanced.

A

52

52) What is the advantage of having small, needlelike leaves?

A) increased transpiration rate
B) decreased transpiration rate
C) increased efficiency of light capture

D) decreased efficiency of light capture

B

53

53) The plant hormone ________ causes stomatal closures in drought stress conditions.

A) indole-3-acetic acid
B) gibberellin
C) abscisic acid (ABA)

D) ethylene

C

54

54) Plants adapted to arid environments are referred to as ________.

A) mesophytes
B) xerophytes
C) psilophytes

D) halophytes

B

55

55) In xerophytes, ________ are referred to as crypts.

A) stomata recessed in cavities
B) guard cells
C) hairs (trichomes)

D) lower epidermal cells

A

56

56) Which of the following is a net sugar source for a deciduous angiosperm tree?

A) new leaves in early spring
B) fruits in summer
C) roots in early spring

D) roots in early autumn

C

57

57) Arrange the following five events in an order that explains the mass flow of materials in the phloem.

1. Water diffuses into the sieve tubes.
2. Leaf cells produce sugar by photosynthesis.
3. Solutes are actively transported into sieve tubes. 4. Sugar is transported from cell to cell in the leaf. 5. Sugar moves down the stem.

A) 1, 2, 3, 4, 5
B) 2, 4, 3, 1, 5
C) 4, 2, 1, 3, 5
D) 2, 4, 1, 3, 5

B

58

58) Water flows into the source end of a sieve tube because ________.
A) sucrose has been actively transported into the sieve tube, making it hypertonic

B) water pressure outside the sieve tube forces in water
C) the companion cell of a sieve tube actively pumps in water
D) sucrose has been transported out of the sieve tube by active transport

A

59

59) Which of the following supports the finding that sugar translocation in phloem is an active (energy-requiring) process?
A) Sucrose occurs in higher concentrations in companion cells than in the mesophyll cells where it is produced.

B) Movement of water occurs from xylem to phloem and back again.
C) Strong pH differences exist between the cytoplasm of the companion cell and the mesophyll cell.
D) ATPases are abundant in the plasma membranes of the mesophyll cells.

A

60

60) Which one of the following statements about transport of nutrients in phloem is correct?

A) Solute particles are actively transported from phloem at the source.
B) Companion cells control the rate and direction of movement of phloem sap.
C) Differences in osmotic concentration at the source and sink cause a hydrostatic pressure gradient to be formed.

D) A sink is the part of a plant where a particular solute is produced.

C

61

61) In the pressure-flow mechanism, loading of sucrose from companion cells to sieve-tube elements takes place through ________.
A) plasmodesmata
B) facilitated diffusion

C) sucrose-H+ symporters

D) sucrose-H+ antiporters

A

62

62) Which of the following is a correct statement about sugar movement in phloem?

A) Diffusion can account for the observed rates of transport.
B) Movement can occur both upward and downward in the plant.
C) Sugar is translocated from sinks to sources.

D) Only phloem cells with nuclei can perform sugar movement.

B

63

63) Plants do not have a circulatory system like that of some animals. If a water molecule in a plant did "circulate" (that is, go from one point in a plant to another and back in the same day), it would require the activity of ________.
A) only the xylem
B) only the phloem
C) only the endodermis
D) both the xylem and the phloem

D

64

64) Some botanists argue that the entire plant should be considered as a single unit rather than a composite of many individual cells. Which of the following cellular structures best supports this view?
A) cell wall

B) cell membrane
C) vacuole
D) plasmodesmata

D

65

65) Plasmodesmata can change in number, and when dilated can provide a passageway for ________.
A) macromolecules
B) ribosomes

C) chloroplasts
D) mitochondria

A

66

66) The symplastic route can transport ________.

A) sugars, mRNA, and mitochondria
B) mRNA, mitochondria, and proteins
C) mitochondria, mRNA, and viruses

D) viruses, sugars, and mRNA

D

67

1) Which of the following is an adaptation that enhances the uptake of water and minerals by roots?
A) mycorrhizae
B) pumping through plasmodesmata

C) active uptake by vessel elements
D) rhythmic contractions by cells in the root cortex

A

68

2) Which structure or compartment is part of the symplast?

A) the interior of a vessel element
B) the interior of a sieve tube
C) the cell wall of a mesophyll cell

D) an extracellular air space

B

69

3) Movement of phloem sap from a source to a sink

A) occurs through the apoplast of sieve-tube elements.

B) depends ultimately on the activity of proton pumps.

C) depends on tension, or negative pressure potential.

D) results mainly from diffusion.

B

70

4) Photosynthesis ceases when leaves wilt, mainly because

A) the chlorophyll in wilting leaves is degraded.
B) accumulation of CO2 in the leaf inhibits enzymes.
C) stomata close, preventing CO2 from entering the leaf.

D) photolysis, the water-splitting step of photosynthesis, cannot occur when there is a water deficiency.

C

71

5) What would enhance water uptake by a plant cell?

A) decreasing the Ψ of the surrounding solution
B) positive pressure on the surrounding solution
C) the loss of solutes from the cell

D) increasing the Ψ of the cytoplasm

B

72

6) A plant cell with a ΨS of -0.65 MPa maintains a constant volume when bathed in a solution that has a ΨS of -0.30 MPa and is in an open container. The cell has a
A) ΨP of +0.65 MPa.
B) Ψ of -0.65 MPa.

C) ΨP of +0.35 MPa.

D) ΨP of 0 MPa.

C

73

7) Compared with a cell with few aquaporin proteins in its membrane, a cell containing many aquaporin proteins will
A) have a faster rate of osmosis.
B) have a lower water potential.

C) have a higher water potential.
D) accumulate water by active transport.

A

74

8) Which of the following would tend to increase transpiration? A) spiny leaves
B) sunken stomata
C) a thicker cuticle

D) higher stomatal density

D