Campbell Biology Chapter 39 (powell_h)
1) All of the following may function in signal transduction in plants
except
A) calcium ions.
B) nonrandom mutations.
C)
receptor proteins.
D) phytochrome.
E) secondary messengers.
Answer: B
2) External stimuli would be received most quickly by a plant cell if
the receptors for signal transduction were located in the
A)
plasma membrane.
B) cytoplasmic matrix.
C) endoplasmic
reticulum.
D) nuclear membrane.
E) nucleoplasm.
Answer: A
3) What would happen if the secondary messenger cGMP was blocked in
the de-etiolation pathway?
A) Specific protein kinase 1 would be
activated, and greening would occur.
B) Ca2+ channels would not
open, and no greening would occur.
C) Ca2+ channels could open,
and specific protein kinase 2 could still be produced.
D) No
transcription of genes that function in de-etiolation would occur.
E) Transcription of de-etiolation genes in the nucleus would not
be affected.
Answer: C
4) If protein synthesis was blocked in etiolated cells, what would be
necessary for the "greening" of these cells?
A)
reception of light by phytochrome
B) activation of protein
kinase 1 by cAMP
C) activation of protein kinase 2 by Ca2+
D) post-translational modification of existing proteins
E)
100-fold decrease in cytosolic Ca2+ levels
Answer: D
5) The detector of light during de-etiolation (greening) of a tomato
plant is (are)
A) carotenoids.
B) xanthophylls.
C)
phytochrome.
D) chlorophyll.
E) auxin.
Answer: C
6) Charles and Francis Darwin concluded from their experiments on
phototropism by grass seedlings that the part of the seedling that
detects the direction of light is the
A) tip of the coleoptile.
B) part of the coleoptile that bends during the response.
C) base of the coleoptile.
D) cotyledon.
E)
phytochrome in the leaves.
Answer: A
7) Plants growing in a partially dark environment will grow toward
light in a response called phototropism. Which of the following
statements is true regarding phototropism?
A) It is caused by an
electrical signal.
B) One chemical involved is ethylene.
C) Auxin causes a growth increase on one side of the stem.
D) Auxin causes a decrease in growth on the side of the stem
exposed to light.
E) Removing the apical meristem enhances phototropism.
Answer: C
8) Which of the following conclusions is supported by the research of
both Went and Charles and Francis Darwin on shoot responses to light?
A) When shoots are exposed to light, a chemical substance
migrates toward the light.
B) Agar contains a chemical substance
that mimics a plant hormone.
C) A chemical substance involved in
shoot bending is produced in shoot tips.
D) Once shoot tips have
been cut, normal growth cannot be induced.
E) Light stimulates
the synthesis of a plant hormone that responds to light.
Answer: C
9) We know from the experiments of the past that plants bend toward
light because
A) they need sunlight energy for photosynthesis.
B) the sun stimulates stem growth.
C) cell expansion is
greater on the dark side of the stem.
D) auxin is inactive on
the dark side of the stem.
E) phytochrome stimulates florigen production.
Answer: C
10) Which of the following is a major mechanism whereby hormones
control plant development?
A) cell respiration via regulation of
the citric acid cycle
B) cell division via the cell cycle
C) cell elongation through production of cellulase
D) cell
differentiation through altered spliceosome activity
E) cell
synthesis of proteins via altered gene expression
Answer: B
11) Evidence for phototropism due to the asymmetric distribution of
auxin moving down the stem
A) was first demonstrated in the
coleoptiles of monocots.
B) has been found in all monocots and
most eudicots.
C) has been shown to involve only IAA stimulation
of cell elongation on the dark side of the stem.
D) can be
demonstrated with unilateral red light, but not blue light.
E)
is now thought by most plant scientists not to involve the shoot tip.
Answer: A
12) According to modern ideas about phototropism in plants,
A)
light causes auxin to accumulate on the shaded side of a plant stem.
B) auxin indirectly inhibits elongation of plant stem cells.
C) auxin is produced by the apical meristem of the coleoptile
and moves downward.
D) all hormones move downward via the xylem.
E) cytokinins are more directly involved than auxins.
Answer: A
13) A plant seedling bends toward sunlight because
A) auxin
migrates to the lower part of the stem due to gravity.
B) there
is more auxin on the light side of the stem.
C) auxin is
destroyed more quickly on the dark side of the stem.
D) auxin is
found in greatest abundance on the dark side of the stem.
E)
gibberellins produced at the stem tip cause phototropism.
Answer: D
14) The apical bud of a shoot produces ________, resulting in the
inhibition of lateral bud growth.
A) abscisic acid
B)
ethylene
C) cytokinin
D) gibberellin
E) auxin
Answer: E
15) After some time, the tip of a plant that has been forced into a
horizontal position grows upward. This phenomenon is related to
A) calcium release from the endoplasmic reticulum of shaded
cells.
B) whether the plant is in the northern or southern
hemisphere.
C) gibberellin production by stems.
D) auxin
production in cells receiving red light.
E) auxin movement
toward the lower side of the stem.
Answer: E
16) Gravitropism in plant shoots and roots differ in that
A)
only shoots depend upon auxin distribution.
B) only shoots
depend upon the aggregation of statoliths.
C) only roots exhibit
rapid elongation of specific cells.
D) only roots sense gravity
at the tips.
E) the threshold and response time is much less in
shoots than in roots.
Answer: E
17) The ripening of fruit and the dropping of leaves and fruit are
principally controlled by
A) auxins.
B) cytokinins.
C) indole acetic acid.
D) ethylene.
E) carbon
dioxide concentration (in air).
Answer: D
18) Which plant hormones would likely be found in high amounts in a
sprouting vegetative stem?
A) auxins, gibberellins, cytokinins
B) gibberellins, brassinosteroids, cytokinins
C) auxins,
abscisic acid, ethylene
D) auxins, phytochrome, brassinosteroids
E) gibberellins, cytokinins, abscisic acid
Answer: A
19) Which of the following plant hormones would be found in very low
amounts in a mature, water-stressed tomato plant?
A) auxins,
abscisic acid, brassinosteroids
B) auxins, gibberellins,
cytokinins
C) gibberellins, cytokinins, ethylene
D)
phytochrome, cytokinins, abscisic acid
E) brassinosteroids,
ethylene, phytochrome
Answer: B
20) The plant hormone involved in aging and ripening of fruit is
A) auxin.
B) ethylene.
C) florigen.
D)
abscisic acid.
E) gibberellin.
Answer: B
21) When growing plants in culture, IAA is used to stimulate cell
enlargement. Which plant growth regulator has to now be added to
stimulate cell division?
A) ethylene
B) indoleacetic acid
C) gibberellin
D) cytokinin
E) abscisic acid
Answer: D
22) Why do coleoptiles grow toward light?
A) Auxin is destroyed
by light.
B) Gibberellins are destroyed by light.
C) Auxin
synthesis is stimulated in the dark.
D) Auxin moves away from
the light to the shady side.
E) Gibberellins move away from the
light to the shady side.
Answer: D
23) Which of the following statements applies to plant growth
regulators?
A) They only act by altering gene expression.
B) They often have a multiplicity of effects.
C) They function independently of other hormones.
D) They directly control plant protein synthesis and assembly.
E) They affect the division and elongation, but not the
differentiation, of cells.
Answer: B
24) Plant hormones produce their effects by
A) altering the
expression of genes.
B) modifying the permeability of the plasma
membrane.
C) modifying the structure of the nuclear envelope
membrane.
D) altering the expression of genes and modifying the
permeability of the plasma membrane.
E) modifying the
permeability of the plasma membrane and modifying the structure of the
nuclear envelope membrane.
Answer: D
25) Why might animal hormones function differently than plant
hormones?
A) Animal receptors are very different than plant
receptors.
B) Plant cells have a cell wall that blocks passage
of many hormones.
C) Plants must have more precise timing of
their reproductive activities.
D) Plants are much more variable
in their morphology and development than animals.
E) Animal
receptors are more hydrophobic than plant receptors.
Answer: D
26) Which of the following hormones would never be found in high
concentrations in a dormant overwintering flower bud?
A) auxin
B) cytokinins
C) abscisic acid
D) ethylene
E) gibberellins
Answer: D
27) Plant hormones can have different effects at different
concentrations. This explains how
A) some plants are long-day
plants and others are short-day plants.
B) signal transduction
pathways in plants are different from those in animals.
C) plant
genes recognize pathogen genes.
D) auxin can stimulate cell
elongation in apical meristems, yet will inhibit the growth of
axillary buds.
E) gibberellin concentration can both induce and
break dormancy.
Answer: D
28) Auxins (IAA) in plants are known to affect all of the following
phenomena except
A) geotropism of shoots.
B) maintenance
of dormancy.
C) phototropism of shoots.
D) inhibition of
lateral buds.
E) fruit development.
Answer: B
29) How does indoleacetic acid affect fruit development?
A) by
preventing pollination
B) by inhibiting formation of the ovule
C) by promoting gene expression in cambial tissue
D) by
promoting rapid growth of the ovary
E) by inducing the formation
of brassinosteroids
Answer: D
30) Oat seedlings are sometimes used to study auxins because
A)
they are a readily accessible monocot, and auxins affect only
monocots.
B) they have a stiff coleoptile.
C) they green
rapidly in the light.
D) their coleoptile exhibits a strong
positive phototropism.
E) monocots inactivate synthetic auxins.
Answer: D
31) Auxin triggers the acidification of cell walls, which results in
rapid growth, but also stimulates sustained, long-term cell
elongation. What best explains how auxin brings about this dual growth
response?
A) Auxin binds to different receptors in different
cells.
B) Different concentrations of auxin have different
effects.
C) Auxin causes second messengers to activate both
proton pumps on the plasma membrane and certain genes within the same
cells.
D) The dual effects are due to two different types of
auxins that are produced by different genes.
E) Other
antagonistic hormones modify auxin's effects.
Answer: C
32) If a farmer wanted more loosely packed clusters of grapes, he
would most likely spray the immature bunches with
A) auxin.
B) gibberellins.
C) cytokinins.
D) abscisic acid.
E) ethylene.
Answer: B
33) Which of the following plant hormones are most likely to act
synergistically if expressed or applied to a drought-stricken plant?
A) auxin and ethylene
B) phytochrome and gibberellins
C) gibberellins and abscisic acid
D) abscisic acid and
ethylene
E) brassinosteroids and cytokinins
Answer: D
34) Which of the following statements best summarizes the acid growth
hypothesis in an actively growing shoot?
A) Auxin stimulates
proton pumps in the plasma membrane and tonoplast.
B)
Auxin-activated proton pumps lower the pH of the cell wall, which
breaks bonds and makes the walls more flexible
C) Auxins and
gibberellins together act as a lubricant to help stretch cellulose
microfibrils.
D) Auxins activate aquaporins that increase turgor
pressure in the cells.
E) Auxins and gibberellins are
transported to the vacuoles to build up turgor pressure.
Answer: B
35) According to the acid growth hypothesis, auxin works by
A)
dissolving sieve plates, permitting more rapid transport of nutrients.
B) dissolving the cell membranes temporarily, permitting cells
that were on the verge of dividing to divide more rapidly.
C)
changing the pH within the cell, which would permit the electron
transport chain to operate more efficiently.
D) increasing wall
plasticity and allowing the affected cell walls to elongate.
E)
greatly increasing the rate of deposition of cell wall material.
Answer: D
36) Which of the following hormones would be most useful in promoting
the rooting of plant cuttings?
A) oligosaccharins
B)
abscisic acid
C) cytokinins
D) gibberellins
E) auxins
Answer: E
37) Which of the following plant hormones would most likely be found
in high concentrations in a mature, slightly overripe fruit?
A)
auxins and cytokinins
B) auxins and abscisic acid
C)
gibberellins and cytokinins
D) cytokinins and ethylene
E)
abscisic acid and ethylene
Answer: E
38) The aleurone layer is stimulated to release ________ and ________
as a result of giberrellin release from the embryo.
A) proteins;
amino acids
B) carbohydrates; sugars
C) auxins; cytokinins
D) amylase; protease
E) RNAase; DNAase
Answer: D
39) Which of the following field treatments would be most likely to
result in a wheat or corn field with most of the plants of uniform
height?
A) auxin spray early in the season
B) gibberellin
spray early in the season
C) abscisic acid spray late in the
season
D) auxin spray late in the season
E) auxin and
gibberellin spray late in the season
Answer: C
40) If you were shipping green bananas to a supermarket thousands of
miles away, which of the following chemicals would you want to
eliminate from the plants' environment?
A) CO₂
B)
cytokinins
C) ethylene
D) auxin
E) gibberellic acids
Answer: C
41) Which of the following is currently the most powerful method of
research on plant hormones?
A) comparing photoperiodic responses
B) comparing tropisms with turgor movements
C) subjecting
plants to various abiotic stresses
D) studying plant/animal
interactions
E) analyzing mutant plants
Answer: E
42) We tend to think of plants as immobile when, in fact, they can
move in many ways. Which of the following is a legitimate way in which
plants move?
A) stretching or shrinking movements up or down in
response to light
B) folding and unfolding of leaves using
muscle-like tissues
C) growth movements toward or away from
light
D) cessation of plant growth in response to wind or touch
E) rapid responses using action potentials from nervous tissue
cells similar to those found in the nervous tissue of animals
Answer: C
43) Which of the following plant growth responses is primarily due to
the action of auxins?
A) leaf abscission
B) fruit
development
C) cell division
D) the detection of
photoperiod
E) cell elongation
Answer: E
44) Experiments on the positive phototropic response of plants
indicate that
A) light destroys auxin.
B) auxin moves down
the plant apoplastically.
C) auxin is synthesized in the area
where the stem bends.
D) auxin can move to the shady side of the
stem.
E) auxin is only of secondary importance in the process.
Answer: D
45) Why are lateral buds often inhibited from sprouting even though a
stem may be actively elongating?
A) The cells of lateral buds
are more sensitive to auxin than stem cells.
B) Lateral buds are
high in abscisic acid that prevents elongation.
C) Lateral buds
are low in gibberellins.
D) Stem cells lack receptors for
auxin.
E) Stem cells can overcome auxin inhibition with high
levels of gibberellins.
Answer: A
46) The synthesis of which of the following hormones would be a
logical first choice in an attempt to produce normal growth in mutant
dwarf plants?
A) indoleacetic acid
B) cytokinin
C)
gibberellin
D) abscisic acid
E) ethylene
Answer: C
47) Incandescent light bulbs, which have high output of red light,
are least effective in promoting
A) photosynthesis.
B)
seed germination.
C) phototropism.
D) flowering.
E)
entrainment of circadian rhythms.
Answer: C
48) Both red and blue light are involved in
A) stem elongation.
B) photoperiodism.
C) positive phototropism.
D)
tracking seasons.
E) all of the above.
Answer: A
49) Seed packets give a recommended planting depth for the enclosed
seeds. The most likely reason some seeds are to be covered with only
1/4 inch of soil is that the
A) seedlings do not produce a
hypocotyl.
B) seedlings do not have an etiolation response.
C) seeds require light to germinate.
D) seeds require a
higher temperature to germinate.
E) seeds are very sensitive to waterlogging.
Answer: C
50) A short-day plant will flower only when
A) days are shorter
than nights.
B) days are shorter than a certain critical value.
C) nights are shorter than a certain critical value.
D)
nights are longer than a certain critical value.
E) days and
nights are of equal length.
Answer: D
51) A flash of red light followed by a flash of far-red light given
during the middle of the night to a short-day plant will likely
A) cause increased flower production.
B) have no effect
upon flowering.
C) inhibit flowering.
D) stimulate
flowering.
E) convert florigen to the active form.
Answer: B
52) Many plants flower in response to day-length cues. Which of the
following statements best summarizes this phenomenon?
A) As a
rule, short-day plants flower in the summer.
B) As a rule,
long-day plants flower in the spring or fall.
C) Long-day plants
flower in response to long days, not short nights.
D) Flowering
in day-neutral plants is only influenced by day length if there is an
exceptionally warm spring.
E) Flowering in short-day and
long-day plants is controlled by phytochrome.
Answer: E
53) Which of the following treatments would enhance the level of the
Pfr form of phytochrome?
A) exposure to far-red light
B)
exposure to red light
C) long dark period
D) inhibition of
protein synthesis
E) synthesis of phosphorylating enzymes
Answer: B
54) Most plants close their stomata at night. What color of light
would be most effective in promoting stomatal opening in the middle of
the night?
A) red
B) far-red
C) blue
D) red
followed by far-red
E) far-red followed by blue
Answer: C
55) The houseplants in a windowless room with only fluorescent lights
begin to grow tall and leggy. Which of the following treatments would
promote more normal growth?
A) Leave the lights on at night as
well as during the day.
B) Add additional fluorescent tubes to
increase the light output.
C) Add some incandescent bulbs to
increase the amount of red light.
D) Set a timer to turn on the
lights for 5 minutes during the night.
E) Turn off the lights
for 5 minutes during the day.
Answer: C
56) In legumes, it has been shown that "sleep" (nastic)
movements are correlated with
A) positive thigmotropisms.
B) rhythmic opening and closing of K+ channels in motor cell
membranes.
C) senescence (the aging process in plants).
D)
flowering and fruit development.
E) ABA-stimulated closing of
guard cells caused by loss of K+.
Answer: B
57) Which of the following statements is correct with regards to a
"circadian rhythm" in plants?
A) It may have the same
signal transduction pathway in all organisms.
B) Once set, it
cannot be changed.
C) It works independently of photoperiodic
responses.
D) Once set, it is independent of external signals.
E) It can be changed to a longer or shorter period by altering
the light quality.
Answer: A
58) The biological clock controlling circadian rhythms must
ultimately
A) depend on environmental cues.
B) affect gene
transcription.
C) stabilize on a 24-hour cycle.
D) speed
up or slow down with increasing or decreasing temperature.
E) do
all of the above.
Answer: B
59) Plants often use changes in day length (photoperiod) to trigger
events such as dormancy and flowering. It is logical that plants have
evolved this mechanism because photoperiod changes
A) are more
predictable than air temperature changes.
B) alter the amount of
energy available to the plant.
C) are modified by soil
temperature changes.
D) can reset the biological clock.
E)
are correlated with moisture availability.
Answer: A
60) If the range of a species of plants expands to a higher latitude,
which of the following processes is the most likely to be modified by
natural selection?
A) circadian rhythm
B) photoperiodic
response
C) phototropic response
D) biological clock
E) thigmomorphogenesis
Answer: B
61) What does a short-day plant require in order to flower?
A)
a burst of red light in the middle of the night
B) a burst of
far-red light in the middle of the night
C) a day that is longer
than a certain length
D) a night that is longer than a certain
length
E) a higher ratio of Pr to Pfr
Answer: D
62) If a short-day plant has a critical night length of 15 hours,
then which of the following 24-hour cycles will prevent flowering?
A) 8 hours light/16 hours dark
B) 4 hours light/20 hours
dark
C) 6 hours light/2 hours dark/light flash/16 hours dark
D) 8 hours light/8 hours dark/light flash/8 hours dark
E)
2 hours light/20 hours dark/2 hours light
Answer: D
63) A long-day plant will flower if
A) the duration of
continuous light exceeds a critical length.
B) the duration of
continuous light is less than a critical length.
C) the duration
of continuous darkness exceeds a critical length.
D) the
duration of continuous darkness is less than a critical length.
E) it is kept in continuous far-red light.
Answer: D
64) Plants that have their flowering inhibited by being exposed to
bright lights at night are
A) day-neutral plants.
B)
short-night plants.
C) devoid of phytochrome.
D) short-day
plants.
E) long-day plants.
Answer: D
65) Classic experiments suggested that a floral stimulus, florigen,
could move across a graft from an induced plant to a noninduced plant
and trigger flowering. Recent evidence using Arabidopsis has recently
shown that florigen is probably
A) a phytochrome molecule that
is activated by red light.
B) a protein that is synthesized in
leaves, travels to the shoot apical meristems, and initiates
flowering.
C) a membrane signal that travels through the
symplast from leaves to buds.
D) a second messenger that induces
Ca++ ions to change membrane potential.
E) a transcription
factor that controls the activation of florigen-specific genes.
Answer: B
66) A short-day plant exposed to nights longer than the minimum for
flowering but interrupted by short flashes of light
A) never
flower.
B) might flower depending upon the duration of the light
flash.
C) will not be affected and will flower.
D) might
flower depending upon the wavelengths of the light flashes.
E)
will still flower if ethylene is administered.
Answer: D
<p>67) A long-day plant will flower <br>A) in the late fall. <br>B) when the night is shorter than a critical value. <br>C) only under artificial light in the summer. <br>D) during short days with proper fertilization. <br>E) regardless of the photoperiod imposed.</p> <p>67) A long-day plant will flower <br>A) in the late fall. <br>B) when the night is shorter than a critical value. <br>C) only under artificial light in the summer. <br>D) during short days with proper fertilization. <br>E) regardless of the photoperiod imposed.</p>
Answer: B
68) What do the results of research on gravitropic responses of roots
and stems show?
A) Different tissues have the same response to
auxin.
B) The effect of a plant hormone can depend on the
tissue.
C) Some responses of plants require no hormones at all.
D) Light is required for the gravitropic response.
E)
Cytokinin can only function in the presence of auxin.
Answer: B
69) Which of the following best describes positive gravitropism
exhibited by plant roots?
A) It is mediated by auxin similar to
the phototropism responses in shoots.
B) It depends on an
inhibition of elongation of some cells.
C) Gravity causes
gibberellins to accumulate on the lower side of roots.
D) The
phenomenon depends upon inhibition of cell elongation of certain root
cells by abscisic acid.
E) All of the above are correct.
Answer: A
70) Vines in tropical rain forests must grow toward large trees
before being able to grow toward the sun. To reach a large tree, the
most useful kind of growth movement for a tropical vine presumably
would be the opposite of
A) positive thigmotropism.
B)
positive phototropism.
C) positive gravitropism.
D) sleep
movements.
E) circadian rhythms.
Answer: B
71) A botanist discovers a plant that lacks the ability to form
starch grains in root cells, yet the roots still grow downward. This
evidence refutes the long-standing hypothesis that
A) falling
statoliths trigger gravitropism.
B) starch accumulation triggers
the negative phototropic response of roots.
C) starch grains
block the acid growth response in roots.
D) starch is converted
to auxin, which causes the downward bending in roots.
E) starch
and downward movement are necessary for thigmotropism.
Answer: A
72) Which of the following watering regimens will be most effective
at keeping a lawn green during the hot, dry summer months?
A)
daily sprinkling to soak the soil to 0.5 inch
B) sprinkling
every other day to soak the soil to 1.0 inch
C) sprinkling every
third day to soak the soil to 2.0 inches
D) daily sprinkling to
soak the soil to 0.5 inch or sprinkling every other day to soak the
soil to 1.0 inch
E) sprinkling every other day to soak the soil
to 1.0 inch or sprinkling every third day to soak the soil to 2.0 inches
Answer: C
73) You are part of a desert plant research team trying to discover
crops that will be productive in arid climates. You discover a plant
that produces a hormone under water-deficit conditions that triggers a
suite of drought responses. Most likely the hormone is
A) ABA.
B) GA.
C) IAA.
D) 2, 4-D.
E) salicylic acid.
Answer: A
74) If you wanted to genetically engineer a plant to be more
resistant to drought, increasing amounts of which of the following
hormones might be a good first attempt?
A) abscisic acid
B) brassinosteroids
C) gibberellins
D) cytokinins
E) auxin
Answer: A
75) Plant cells begin synthesizing large quantities of heat-shock
proteins
A) after the induction of chaperone proteins.
B)
in response to the lack of CO₂ following the closing of stomata by
ethylene.
C) when desert plants are quickly removed from high
temperatures.
D) when they are subjected to moist heat (steam)
followed by electric shock.
E) whenever the external temperature
exceeds the threshold where photosynthesis is negatively impacted.
Answer: E
76) Most scientists agree that global warming is underway; thus, it
is important to know how plants respond to heat stress. Which of the
following would be a useful line of inquiry to try and improve plant
response and survival to heat stress?
A) the production of
heat-stable carbohydrates
B) increased production of heat-shock
proteins
C) the opening of stomata to increase evaporational
heat loss
D) protoplast fusion experiments with xerophytic
plants
E) all of the above
Answer: B
77) In extremely cold regions, woody species may survive freezing
temperatures by
A) emptying water from the vacuoles to prevent
freezing.
B) decreasing the numbers of phospholipids in cell
membranes.
C) decreasing the fluidity of all cellular membranes.
D) producing canavanine as a natural antifreeze.
E)
increasing cytoplasmic levels of specific solute concentrations, such
as sugars.
Answer: E
78) Which of the following is a likely response of plants to cold
stress?
A) the production of a specific solute "plant
coagulant " that reduces water loss
B) reducing the size of
ice crystals
C) conversion of the fluid mosaic cell membrane to
a solid mosaic one
D) an increase in sterol concentration of
membrane lipids so that the membranes remain flexible
E)
increasing the proportion of unsaturated fatty acids in the membranes
Answer: C
79) Bald cypress and loblolly pine are both gymnosperm trees native
to the southern United States. The cypress grows in swamps; the pine
grows in sandy soil. How do you think their anatomies differ?
A)
There are larger intercellular spaces in the roots of the cypress than
in the roots of the pine.
B) Water-conducting cells are larger
in the stems of the cypress than in the stems of the pine.
C)
The springwood and summerwood are more distinct in the cypress.
D) There is less parenchyma in the roots of the cypress than in
the pine roots.
E) There are no major anatomical differences
between these species because they're both gymnosperms.
Answer: A
80) The initial response of the root cells of a tomato plant watered
with seawater would be to
A) rapidly produce organic solutes in
the cytoplasm.
B) rapidly expand until the cells burst.
C)
begin to plasmolyze as water is lost.
D) actively transport
water from the cytoplasm into the vacuole.
E) actively absorb
salts from the seawater.
Answer: C
81) Which of the following best explains both the growth of a vine up
the trunk of a tree as well as the directional growth of a houseplant
toward a window?
A) nastic movement
B) taxic movement
C) tropism response
D) morphological response
E) acclimation
Answer: C
82) The rapid leaf movements resulting from a response to touch
(thigmotropism) primarily involve
A) rapid growth response.
B) potassium channels.
C) nervous tissue.
D)
aquaporins.
E) stress proteins.
Answer: B
83) Which of the following is the most likely plant response to an
attack by herbivores?
A) leaf abscission to prevent further
loss
B) early flowering to try and reproduce before being eaten
C) production of chemical compounds for defense or to attract
predators
D) production of physical defenses, such as thorns
E) production of thicker bark and cuticle to make it more
difficult to eat
Answer: D
84) In order for a plant to initiate chemical responses to herbivory,
A) the plant must be directly attacked by an herbivore.
B)
volatile "signal" compounds must be perceived.
C)
gene-for-gene recognition must occur.
D) phytoalexins must be
released.
E) it must be past a certain developmental age.
Answer: B
85) Plants are affected by an array of pathogens. Which of the
following is a likely plant defense/response against disease?
A)
cells near the point of infection destroying themselves to prevent the
spread of the infection
B) production of chemicals that repel
pathogens
C) transcriptional level recognition followed by
production of stress proteins
D) thickening the cuticle so that
pathogens have trouble penetrating the tissues
E) stopping all
xylem and phloem movement within infected tissues
Answer: A
86) A pathogenic fungus invades a plant. What does the infected plant
produce in response to the attack?
A) antisense RNA
B)
phytoalexins
C) phytochrome
D) statoliths
E)
thickened cellulose microfibrils in the cell wall
Answer: B
87) Which of the following would be the most effective way to prevent
herbivory in a non-woody plant?
A) production of the amino acid
analog canavanine
B) release of insect pheromones
C)
production of foul-tasting compounds
D) thickened cuticle
E) enhanced levels of salicylic acid
Answer: D
88) The transduction pathway that activates systemic acquired
resistance in plants is initially signaled by
A) antisense RNA.
B) Pfr phytochrome.
C) salicylic acid.
D) abscisic
acid.
E) red, but not far-red, light.
Answer: C
89) Which of the following would only be activated or upregulated
after a plant has already been infected by a pathogen?
A)
phytochrome
B) salicylic acid
C) molecular chaperones
D) stress proteins
E) brassinosteroids
Answer: B
90) A plant will recognize a pathogenic invader
A) if it has
many specific plant disease resistance (R) genes.
B) when the
pathogen has an R gene complementary to the plant's antivirulence
(Avr) gene.
C) only if the pathogen and the plant have the same
R genes.
D) if it has the specific R gene that corresponds to
the pathogen molecule encoded by an Avr gene.
E) when the
pathogen secretes Avr protein.
Answer: D
91) What is the probable role of salicylic acid in the defense
responses of plants?
A) to destroy pathogens directly
B) to
activate systemic acquired resistance of plants
C) to close
stomata, thus preventing the entry of pathogens
D) to activate
heat-shock proteins
E) to sacrifice infected tissues by
hydrolyzing cells
Answer: B
92) When an arborist prunes a limb off a valuable tree, he or she
usually paints the cut surface. The primary purpose of the paint is to
A) minimize water loss by evaporation from the cut surface.
B) improve the appearance of the cut surface.
C) stimulate
growth of the cork cambium to "heal" the wound.
D)
block entry of pathogens through the wound.
E) induce the
production of phytoalexins.
Answer: D
93) Plant hormonal control differs from animal hormonal control in
that
A) there are no separate hormone-producing organs in plants
as there are in animals.
B) all production of hormones is local
in plants with little long-distance transport.
C) plants do not
exhibit feedback mechanisms like animals.
D) only animal hormone
concentrations are developmentally regulated.
E) only animal
hormones may have either external or internal receptors.
Answer: A
94) Unlike animal hormones, plant hormones are mainly
A)
hydrophobic molecules.
B) products of stresses in the
environment.
C) small, easily transportable molecules.
D)
unable to cross membranes.
E) direct products of photosynthesis.
Answer: C
95) In cases where plants exhibit generalized defense responses in
organs distant from the infection site, this is termed
A)
hyperactive responses.
B) systemic acquired resistance.
C)
pleiotropy.
D) hyperplasia.
E) general systemic response.
Answer: B
96) The heavy line in Figure 39.1 illustrates the relationship
between auxin concentration and cell growth
in stem tissues. If
the same range of concentrations were applied to lateral buds, what
curve(s) would probably be produced?
A) I
B) II
C)
III
D) II or III
E) I or III
Answer: A
97) The results of this experiment, shown on the left of the graph
(area A), may be used to
A) show that these plants can live
without gibberellin.
B) show that gibberellin is necessary in
positive gravitropism.
C) show that taller plants with more
gibberellin produce fruit (pods).
D) show a correlation between
plant height and gibberellin concentration.
E) study
phytoalexins in plants.
Answer: D
98) This experiment suggests that the unknown amount of gibberellin
in the experimental plant (B) is approximately
A) zero.
B)
0.01 μg/mL.
C) 0.1 μg/mL.
D) 1.0 μg/mL.
E) equal to
the amount of gibberellin in the shortest plant.
Answer: C
99) In nature, poinsettias bloom in early March. Research has shown
that the flowering process is triggered three months before blooming
occurs. In order to make poinsettias bloom in December, florists
change the length of the light-dark cycle in September. Given the
information and clues above, which of the following is a correct
statement about poinsettias?
A) They are short-day plants.
B) They require a light period longer than some set minimum.
C) They require a shorter dark period than is available in
September.
D) The dark period can be interrupted without
affecting flowering.
E) They will flower even if there are brief
periods of far-red illumination during the nighttime.
Answer: A
100) A botanist exposed two groups of the same plant species to two
photoperiods–one with 14 hours of light and 10 hours of dark and the
other with 10 hours of light and 14 hours of dark. Under the first set
of conditions, the plants flowered, but they failed to flower under
the second set of conditions. Which of the following conclusions would
be consistent with these results?
A) The critical night length
is 14 hours.
B) The plants are short-day plants.
C) The
critical day length is 10 hours.
D) The plants can convert
phytochrome to florigen.
E) The plants flower in the late spring.
Answer: E
101) The hormone that helps plants respond to drought is
A)
auxin.
B) gibberellin.
C) cytokinin.
D) ethylene.
E) abscisic acid.
Answer: E
102) Auxin enhances cell elongation in all of the these ways except
A) increased uptake of solutes.
B) gene activation.
C) acid-induced denaturation of cell wall proteins.
D)
increased activity of plasma membrane proton pumps.
E) cell wall loosening.
Answer: C
103) Charles and Francis Darwin discovered that
A) auxin is
responsible for phototropic curvature.
B) auxin can pass through
agar.
C) light destroys auxin.
D) light is perceived by
the tips of coleoptiles.
E) red light is most effective in shoot phototropism.
Answer: D
104) How may a plant respond to severe heat stress?
A) by
reorienting leaves to increase evaporative cooling
B) by
creating air tubes for ventilation
C) by initiating a systemic
acquired resistance response
D) by increasing the proportion of
unsaturated fatty acids in cell membranes, reducing their fluidity
E) by producing heat-shock proteins, which may protect the
plant's proteins from denaturing
Answer: E
105) The signaling molecule for flowering might be released earlier
than usual in a long-day plant exposed to flashes of
A) far-red
light during the night.
B) red light during the night.
C)
red light followed by far-red light during the night.
D) far-red
light during the day.
E) red light during the day.
Answer: B
106) If a long-day plant has a critical night length of 9 hours,
which 24-hour cycle would prevent flowering?
A) 16 hours light/8
hours dark
B) 14 hours light/10 hours dark
C) 15.5 hours
light/8.5 hours dark
D) 4 hours light/8 hours dark/4 hours
light/8 hours dark
E) 8 hours light/8 hours dark/light flash/8
hours dark
Answer: B
107) A plant mutant that shows normal gravitropic bending but does
not store starch in its plastids would require a reevaluation of the
role of ________ in gravitropism.
A) auxin
B) calcium
C) statoliths
D) light
E) differential growth
Answer: C
108) Which type of mutant would be most likely to produce a bushier
phenotype?
A) auxin overproducer
B) strigolactone
overproducer
C) cytokinin underproducer
D) gibberellin
overproducer
E) strigolactone underproducer
Answer: E