CHAPTER 34—TRANSPORT IN PLANTS
MULTIPLE CHOICE
1. The process that a tall tree uses to move water to the leaves at the top of the tree involves primarily
a.
cohesion and evaporation.
b.
evaporation and pumps.
c.
capillary action and pumps.
d.
positive pressure from roots and cohesion.
e.
capillary action and positive pressure from roots.
2. The processes that plants use to move water, sugar, and other solutes through their bodies involves
primarily
a.
cohesion and evaporation.
b.
evaporation and pumps.
c.
capillary action and pumps.
d.
positive pressure from roots and cohesion.
e.
capillary action and positive pressure from roots.
3. Which of the following is NOT transported in phloem?
a.
carbohydrates
b.
hormones
c.
amino acids
d.
fatty acids
e.
nitrate
4. The membrane potential refers to the ____ across a cell membrane.
a.
difference in water concentration
b.
charge difference
c.
rate of movement
d.
distance
e.
difference in salt concentration
674
5. Which of the following should you expect to find for a living plant cell in a living plant?
a.
a cytoplasm that is much more negatively charged than the fluid outside the cell
b.
a cytoplasm that has essentially the same charge as the fluid outside the cell
c.
a cytoplasm that is slightly more positively charged than the fluid outside the cell
d.
a cytoplasm that is much more positively charged than the fluid outside the cell
e.
a cytoplasm that is slightly more negatively charged than the fluid outside the cell
6. Generally, the energy for pumping protons outside of a plant cell comes most directly from
a.
sunlight.
b.
starch.
c.
ATP.
d.
diffusion.
e.
glucose.
7. Which of the following should you expect to be occurring in a living plant cell in a living plant?
a.
protons moving out of the cell via passive diffusion
b.
protons being actively pumped into the cell
c.
protons moving out of the cell via facilitated diffusion
d.
protons being actively pumped out of the cell
e.
protons moving into the cell via passive diffusion
8. The simultaneous movement of sucrose into a cell against its concentration gradient and protons into a
cell with their concentration gradient is best described as an example of
a.
symport.
b.
passive diffusion.
c.
antiport.
d.
facilitated diffusion.
e.
active transport.
9. The simultaneous movement of Na+ out of a cell against its concentration gradient and protons into a
cell with their concentration gradient is best described as an example of
a.
symport.
b.
passive diffusion.
c.
antiport.
d.
facilitated diffusion.
e.
active transport.
10. The movement of NH4+ ions into a cell down an electrochemical gradient (where, when compared to
the outside of the cell, the inside of the cell has less NH4+ ions) is best described as an example of
a.
symport.
b.
passive diffusion.
c.
antiport.
d.
facilitated diffusion.
e.
active transport.
11. The typical movement of xylem sap from roots to shoot parts is best described as
a.
facilitated diffusion.
b.
symport.
c.
guttation.
d.
osmosis.
e.
bulk flow.
12. Individual plant cells typically gain or lose water mainly via
a.
facilitated diffusion.
b.
symport.
c.
guttation.
d.
osmosis.
e.
bulk flow.
13. Water potential, the inherent capacity of water molecules to move from one site to another when
conditions dictate, is typically represented by the Greek letter ____.
a.
b.
c.
d.
e.
14. Consider a living plant cell in a living leaf that is not wilted. The solute potential (S) of such a cell
____ than that in the fluids surrounding the cell.
a.
is typically lower
b.
varies widely from higher to lower
c.
is typically higher
d.
is typically about the same as
e.
is typically less negative
15. Consider a living plant cell in a living leaf that is not wilted. The pressure potential (P) of such a cell
____ than that in the fluids surrounding the cell.
a.
is typically lower
b.
varies widely from higher to lower
c.
is typically higher
d.
is typically about the same as
e.
is typically more negative
16. Consider a living plant cell in a living leaf that has a higher water potential than the fluids surrounding
the cell. In such a situation there should be
a.
a net flow of water out of the cell.
b.
gain of water by the cell only if the cell’s pressure potential is high enough.
c.
no net flow of water into or out of the cell.
d.
a net flow of water into the cell.
e.
gain of water by the cell only if the cell’s pressure potential is low enough.
17. Which plant organelle stores solutes and plays a major role in maintaining turgor pressure?
a.
nucleus
b.
cell wall
c.
chloroplast
d.
vacuole
e.
mitochondrion
18. The tonoplast is another name for
a.
the plant nuclear envelope.
b.
a chloroplast.
c.
the cell wall.
d.
an undifferentiated plastid.
e.
the vacuolar membrane.
19. Suppose you discover a mutant plant that cannot actively transport solutes across the tonoplast. Which
of the following should you expect?
a.
The plant will wilt easily.
b.
The plant will generally be like a normal plant.
c.
The plant will not have leaves.
d.
The plant will not have roots.
e.
The plant cells will not be able to divide.
20. Aquaporins are
a.
channel proteins for water.
b.
carrier proteins for solutes.
c.
channel proteins for solutes.
d.
carrier proteins for water.
e.
carrier proteins for water and solutes.
21. If the of surrounding soil is higher than that in living root epidermal cells, then water should
a.
leave the root cells, making them flaccid.
b.
enter the root cells, making them turgid.
c.
leave the root cells, making them turgid.
d.
enter the root cells, making them flaccid.
e.
none of these accurately describe water movement.
22. If a living plant cell is placed in a beaker with pure water, it will take up water until
a.
within the cell P = −S.
b.
it bursts.
c.
its P = 0.
d.
its S = S of the pure water.
e.
its S = 0.
23. If a living plant cell is placed in a beaker with a solution that has a value lower than the value of
the plant cell, the plant cell will
a.
take up water until it bursts.
b.
lose water until its = of the solution.
c.
take up water until within the cell P = −S.
d.
take up water until its = S of the solution.
e.
lose water until its S = its P.
24. Suppose a living plant cell has = S = −0.5 MPa. If the plant cell is placed into a beaker filled with a
solution with = 0, then the cell should
a.
take up water until it bursts.
b.
lose water until its = of the solution.
c.
take up water until within the cell P = −S.
d.
take up water until its S = S of the solution.
e.
lose water until its S = its P.
25. Suppose a living plant cell has P = 0.4 MPa and S = −0.5 MPa. If the plant cell is placed into a
beaker filled with a solution with = S = −0.9 MPa, then the cell should
a.
take up water until it bursts.
b.
lose water until its = of the solution.
c.
take up water until within the cell P = −S.
d.
take up water until its S = S of the solution.
e.
lose water until its S = its P.
26. Suppose two living plant cells are in contact with each other so that water, but not solutes, can pass
between them. The cells have the same water potential. One cell has P = 0.3 MPa and S = −0.5 MPa,
while the other cell has S = −0.3 MPa. What is the P of the second cell?
a.
P = −0.8 MPa
b.
P = 0 MPa
c.
P = 0.5 MPa
d.
P = 0.8 MPa
e.
P = 0.1 MPa
27. What is the P of a living plant cell that has = −0.2 MPa and S = −0.4 MPa?
a.
P = −0.6 MPa
b.
P = 0.08 MPa
c.
P = −0.2 MPa
d.
P = 0.2 MPa
e.
P = 0.5 MPa
28. A plant cell with a P = 0.2 MPa maintains a constant volume when bathed in a solution that
has a S = −0.2 MPa and is in an open container. What do you know about the cell?
a.
The cell has a S = 0.4 MPa.
b.
The cell has a S = −0.2 MPa.
c.
The cell has a S = −0.4 MPa.
d.
The cell has a = −0.4 MPa.
e.
The cell has a = 0.2 MPa
29. Studies where mRNA for tonoplast intrinsic protein from a plant were injected into frog eggs resulted
in ____ the egg cells when they were placed in a hypotonic medium.
a.
rapid water loss by
b.
no effect on
c.
slight swelling of
d.
slow water loss by
e.
swelling and bursting of
30. In its normal location in plant cells, tonoplast intrinsic protein apparently directly allows
a.
water flow only into the chloroplast.
b.
water flow into the cell across the cell wall.
c.
water flow out of the cell across the cell wall.
d.
water flow both into and out of the vacuole.
e.
water flow only out of the chloroplast.
31. Water can move inside a root via the
a.
symplastic pathway.
b.
transmembrane and symplastic pathways.
c.
transmembrane pathway.
d.
apoplastic, transmembrane, and symplastic pathways.
e.
apoplastic pathway.
32. Water that moves through living cells in a root is following the
a.
symplastic pathway.
b.
transmembrane and symplastic pathways.
c.
transmembrane pathway.
d.
apoplastic, transmembrane, and symplastic pathways.
e.
apoplastic pathway.
33. Water that moves through nonliving regions of root, such as air spaces in root tissue, is following the
a.
symplastic pathway.
b.
transmembrane and symplastic pathways.
c.
transmembrane pathway.
d.
apoplastic, transmembrane, and symplastic pathways.
e.
apoplastic pathway.
34. The Casparian strip of the endodermis stops water from the ____ before it reaches the stele.
a.
symplastic pathway
b.
transmembrane and symplastic pathways
c.
transmembrane pathway
d.
apoplastic, transmembrane, and symplastic pathways
e.
apoplastic pathway
35. Suberin is a waxy substance that is typically associated with the
a.
primary xylem.
b.
root hairs.
c.
endodermis.
d.
tonoplasts.
e.
pericycle.
36. Most mineral ions that plants need are
a.
moved into the symplast via active transport.
b.
moved into the transmembrane pathway via bulk flow.
c.
moved into the apoplast via facilitated diffusion.
d.
moved into the symplast via facilitated diffusion.
e.
moved into the apoplast via bulk flow.
37. Active transport in plant root cells requires that those cells have access to O2. Normally there is enough
O2 available in air pockets in the soil, but flooded soil has very little O2. Thus, unless they have special
adaptations, plants in flooded soil effectively have no active transport in their roots. Which of the
following should you expect to occur for trees without special adaptations to flooding after several
days in flooded soil?
a.
excess uptake of water and minerals in the xylem
b.
wilting of their leaves
c.
bursting of leaf cells due to excess water flow
d.
excess water pushed out at the margins of their leaves
e.
excess uptake of water and minerals in the xylem, and excess water pushed out at the
margins of their leaves
38. Many plants wind up with a Na+ concentration that is considerably lower than that of the surrounding
soil. Which of these plays a key role in allowing for such a difference to exist?
a.
water potential
b.
aquaporins
c.
root cap
d.
endodermis
e.
tonoplast
39. The principal driving force for movement of water into and through the plant shoot is
a.
passive transport.
b.
sunlight.
c.
root pressure.
d.
upward pressure as sugar is forced into the roots.
e.
pumping by the xylem cells.
40. The process of transpiration is driven by
a.
passive transport.
b.
sunlight.
c.
root pressure.
d.
upward pressure as sugar is forced into the roots.
e.
pumping by the xylem cells.
41. The majority of the water in xylem sap typically
a.
is used in capturing light energy.
b.
becomes part of new plant cells.
c.
is used to make sugars.
d.
is stored in older plant cells.
e.
evaporates into the air.
42. The evaporation of water into the air from plant tissues is called
a.
cohesion-tension.
b.
photorespiration.
c.
transpiration.
d.
root pressure.
e.
guttation.
43. According to the cohesion-tension mechanism of water transport, cohesion occurs because
a.
waxy coatings on insides of xylem keep water molecules together in the xylem.
b.
evaporation removes water from the leaves.
c.
water molecules tend to form hydrogen bonds with each other.
d.
water is pushed into the xylem by bulk flow.
e.
water is pushed into the xylem by phloem pressure.
44. According to the cohesion-tension mechanism of water transport, which of the following DOES NOT
contribute to the flow of the xylem sap?
a.
hydrogen bonds between water molecules
b.
adhesion of water molecules to the xylem vessel walls
c.
evaporation of water from the leaves
d.
water potential in leaf cells below that of the leaf xylem
e.
root pressure
45. Most leaf cells are no more than ____ from a xylem vein.
a.
one inch
b.
one centimeter
c.
half a millimeter
d.
50 micrometers
e.
two inches
46. Theoretically, based on the cohesion-tension mechanism, the maximum height for the tallest trees
should be about
a.
50 ft.
b.
130 m.
c.
6 ft.
d.
3 m.
e.
75 m.
47. The principal driving force for guttation is
a.
passive transport.
b.
sunlight.
c.
root pressure.
d.
upward pressure as sugar is forced into the roots.
e.
pumping by the xylem cells.
48. An air temperature rise of 10C will typically ____ evaporation from leaves.
a.
completely eliminate
b.
double the rate of
c.
mostly eliminate
d.
triple the rate of
e.
quadruple the rate of
49. Which of the following DOES NOT have a major effect on the rate of transpiration?
a.
air temperature
b.
relative humidity
c.
air movement
d.
amount of direct solar radiation
e.
daily fluctuations in atmospheric carbon dioxide concentrations