50. Under which condition would you expect essentially no transpiration to occur?
a.
brisk winds
b.
100 percent relative humidity
c.
no winds
d.
1 percent relative humidity
e.
hot air temperature and no winds
51. The major cost to plants for having cuticle-covered epidermis in the shoot system to reduce water loss
is reduced ____ uptake.
a.
carbon dioxide
b.
potassium
c.
nitrogen
d.
calcium
e.
oxygen
52. A plant stoma is found between two
a.
leaves.
b.
root hairs.
c.
xylem veins.
d.
trichomes.
e.
guard cells.
53. Stomata are opened when ____ guard cells and they become ____.
a.
active transport pumps H+ into; turgid
b.
active transport of H+ stops in; flaccid
c.
active transport pumps H+ out of; turgid
d.
active transport pumps H+ into; flaccid
e.
active transport of H+ stops in; turgid
54. Stomata close when ____ guard cells and they become ____.
a.
active transport pumps H+ into; turgid
b.
active transport of H+ stops in; flaccid
c.
active transport pumps H+ out of; turgid
d.
active transport pumps H+ into; flaccid
e.
active transport of H+ stops in; turgid
55. Stomata open when K+ concentration in guard cells ____, followed by water ____ the guard cells by
osmosis.
a.
increases, entering
b.
decreases, entering
c.
decreases, leaving
d.
increases, leaving
e.
increases H+, leaving
56. In most plants stomata are
a.
open during the night and closed during the day.
b.
nearly always open.
c.
closed only when guard cells are not exposed to sunlight.
d.
almost never open.
e.
open during the day and closed during the night.
57. Which of the following generally causes stomata to open?
a.
release of abscisic acid by the roots
b.
a drop in CO2 concentration in leaf air spaces
c.
exposure to red light
d.
a drop in O2 concentration in leaf air spaces
e.
an increase in CO2 concentration in the leaf air spaces
58. Which of the following generally causes stomata to close?
a.
release of abscisic acid by the roots
b.
a drop in CO2 concentration in leaf air spaces
c.
exposure to red light
d.
a drop in O2 concentration in leaf air spaces
e.
an increase in water in the soil
59. Which of the following ions plays the most prominent known role in the opening and closing of
stomata?
a.
Ca2+
b.
Cl−
c.
K+
d.
NH4+
e.
Na+
60. Which has the strongest effect on whether stomata are open or closed?
a.
sunlight
b.
ion concentrations in the xylem
c.
CO2 concentration
d.
O2 concentration
e.
abscisic acid
61. In CAM plants, such as cacti, stomata are
a.
open during the night and closed during the day.
b.
nearly always open.
c.
closed only when guard cells are not exposed to sunlight.
d.
almost never open.
e.
open during the day and closed during the night.
62. Which of the following would you NOT expect to find in phloem sap?
a.
Carbohydrates.
b.
Hormones.
c.
Water.
d.
Amino acids.
e.
Nitrate.
63. The main form in which sugars are transported in the phloem sap is
a.
glucose.
b.
lactose.
c.
starch.
d.
sucrose.
e.
fructose.
64. The general term for long-distance transport of substances in plants is called
a.
cohesion-tension.
b.
translocation.
c.
pressure flow.
d.
osmosis.
e.
transpiration.
65. The hypothesis that high pressure forces phloem sap to flow was tested and supported by studies using
a.
caterpillars.
b.
radiolabeled hormones.
c.
vacuum chambers.
d.
aphids.
e.
radiolabeled sugars.
66. Honeydew is essentially
a.
xylem sap forced out of the margins of leaves.
b.
xylem sap harvested by honeybees.
c.
phloem sap harvested as syrup.
d.
xylem sap separated from syrup.
e.
phloem sap leaving the anus of an aphid.
67. Loading of most carbohydrates produced by photosynthesis into companion cells at a source occurs by
a.
osmosis.
b.
proton pumping.
c.
suction from unloading at a sink.
d.
active transport.
e.
diffusion of water from the xylem.
68. In phloem movement, which of the following does not serve as a source?
a.
photosynthesizing cells in a leaf
b.
roots
c.
photosynthesizing cells in a stem
d.
food storage cells in a stem
e.
soil
69. In phloem movement, which of the following cannot serve as a sink?
a.
young leaves
b.
young roots
c.
developing fruits
d.
tulip bulbs after the plant has bloomed
e.
soil
70. Companion cells load most of the carbohydrates into sieve tube members
a.
through plasmodesmata.
b.
by osmosis.
c.
by antiport.
d.
through carrier proteins.
e.
by symport.
71. At a source the phloem typically has a water potential that is ____ that in surrounding xylem.
a.
lower than
b.
about the same as
c.
higher than
d.
exactly the same as
e.
less negative than
72. When solutes are unloaded from phloem, water
a.
is pumped into the phloem by active transport.
b.
leaves the xylem by osmosis.
c.
moves into the phloem by facilitated diffusion.
d.
is pumped out of the phloem by active transport.
e.
leaves the phloem by osmosis.
73. Plasmodesmata are considered part of the
a.
symplastic pathway.
b.
transmembrane and symplastic pathways.
c.
transmembrane pathway.
d.
apoplastic, transmembrane, and symplastic pathways.
e.
apoplastic pathway.
74. Metabolomics is based on the premise that
a.
plant mitochondria are unique to
harnessing ATP to develop alternative
energy sources.
d.
plant metabolism is difficult to
manipulate.
b.
plant chloroplasts are unique to harnessing
light for energy.
e.
plant metabolism is simple to manipulate.
c.
harnessing the 200,000 to 1 million
different chemicals produced by plant
metabolism for human needs is
increasingly important.
75. What percent of analytes in plant samples identified from mass spectrometry are classified as
“unknown”?
a.
6%
d.
60%
b.
16%
e.
96%
c.
46%
76. Plasmodesmata are
a.
only found in root cells.
b.
connections between xylem and phloem.
c.
incapable of structural change.
d.
able to be opened and closed.
e.
only found in leaf cells.
77. The most widely accepted and supported model that explains the movement of xylem sap is the ____
mechanism.
a.
cohesion-tension
b.
translocation
c.
pressure flow
d.
osmosis
e.
transpiration
78. The most widely accepted and supported model that explains the movement of phloem sap in
flowering plants is the ____ mechanism.
a.
cohesion-tension
b.
translocation
c.
pressure flow
d.
osmosis
e.
transpiration
79. The movement of phloem sap is best described from ____ to ____.
a.
the shoot system; the root system
b.
sinks; sources
c.
the root system; the shoot system
d.
sources; sinks
e.
none of these
80. The movement of xylem sap is best described from ____ to ____.
a.
the shoot system; the root system
b.
sinks; sources
c.
the root system; the shoot system
d.
sources; sinks
e.
none of these
MATCHING
Choice
Provide the letter that represents the plant tissue or tissues that are directly associated with each of the
items given. Each letter may be used once, more than once, or not at all.
a.
xylem
b.
phloem
c.
both xylem and phloem
d.
neither xylem nor phloem
81. bulk flow
82. transport of hormones from growing shoot tips
83. primary transport of ions from leaves
84. primary transport of water from roots
85. dead cells throughout conducting portions
86. companion cells
87. stomata
88. cohesion-tension mechanism
89. transport of sugars
90. trichomes
SHORT ANSWER
91. Discuss permeability in plant cell walls?
92. How does water move so rapidly across plant cell membranes, and why are red blood cells so
important to the process?
93. What processes are responsible for transport of ions such NO3– and Na+? Do the processes differ and
what is the consequence of a failure of transport of the ions?
94. Explain why a dry, hot, breezy day can result in the leaves of certain plants having to completely
replace their water each hour?
95. Explain what happens when NaCl and other salts build up in soils?
MODIFIED TRUE/FALSE
If the statement is true, answer “T”. If the statement is false, answer “F” and make it correct by
changing the underlined word(s) and writing the correct word(s) in the answer blank(s).
96. In a wilted leaf, the protoplast has shrunk away from the cell wall.
97. The living portion of the pathway through which water travels through a root is called the symplastic
pathway.
98. Root epidermal cells can passively transport ions inward from the soil because they cannot follow a
concentration gradient.
99. The loss of water vapor from aerial plant parts is called evapotranspiration.
100. The root-to-shoot water in a plant is called the transpiration stream.
101. Rising air temperatures at the leaf surface can increase evaporation, although wilting can also cool a
leaf somewhat.
102. In plants, the long-distance transport of substances is called transpiration.
103. When an ant tends an aphid, it would be benefiting the aphid by removing honeydew from the aphids
anus, and benefiting from obtaining carbon.
104. In some plants, companion cells become modified into phloem cells that facilitate the short-distance
transport of various organic solutes from the symplast into the apoplast.
105. Translocation in sieve tubes requires active transport.
ESSAY
106. Explain the process that occurs when a stoma goes from closed to open.
107. Explain the processes of phloem loading and unloading in a flowering plant.