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Examination of a typical dicotyledon seed
reveals that it
a. is made mostly of meristematic tissue
used for the storage of food.
b. can be stimulated to germinate by the
application of abscisic acid.
c. forms from the union of a microscopic
mother cell with a meagspore mother cell.
d. shows the presence of a well-developed
coleoptile.
e. contains the first-foliage plumule formed
at the apical meristem.
Flowering in plants such as tobacco and
cocklebur and the germination of certain
lettuce seeds are induced primarily by
a. photoperiodism.
b. temperature.
c. negative feedback.
d. circadian rhythms.
e. lunar phases.
Gibberellic acid stimulates the cells of
germinating grass seeds to produce mRNA
molecules that code for hydrolytic enzymes.
In this case the role of gibberellic acid can best
be described as that of
a. a regulator of gene activity.
b. a stimulator of hydrolase secretion.
c. a stimulator of DNA replication.
d. an allosteric activator of hydrolase.
e. an activator of translation.
All of the following are plant growth regulators
EXCEPT
a. ethylene.
b. indoleacetic acid.
c. abscisic acid.
d. cytokinins.
e. anthocyanin.
Auxins are responsible for many plant growth
responses, including all of the following
EXCEPT
a. phototropism.
b. formation of adventitious roots.
c. apical dominance.
d. detection of photoperiod.
e. none of these
Movement of plants that is independent of the
direction of the stimulus is known as
a. tropism.
b. nastic movement.
c. auxic movement.
d. all of these
e. none of these
In order to flower, what does a short day plant
need?
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 ceratin
length
e. none of these
In nature, poinsettias bloom in early March. Research
has shown that these plants are triggered to flower three
months before they actually bloom. The trigger is the
length of the light-dark cycle. In order to get poinsettias
to 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 FALSE?
a. Poinsettias are short day plants.
b. Poinsettias require a light period shorter than
some maximum.
c. Poinsettias require a longer night period than
is available in September.
d. The dark period can be interrupted without
affecting the flower.
e. all are correct
A botanist exposed 2 groups of plants (of the same
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 flower in spring.
e. all of these
If a plant is mechanically stimulated, it will grow
shorter, thicker stems. This response is
a. caused by an increase in turgor.
b. an adaptation to windy environments.
c. both a and b
d. neither a nor b
One effect of gibberrellins is to stimulate the
aleurone layer of certain seeds to reproduce
a. RuBP carboxylase.
b. lipids.
c. abscisic acid.
d. starch.
e. amylase.
We know from experiments of the past that
plants bend toward light because
a. the sum stimulates cell growth.
b. cell expansion is greater on the dark
side of the stem.
c. its warmer in the direction of the sun.
d. auxin is inactive on the dark side of
the stem.
The application of which of the following
hormones would be a logical first choice in an
attempt to produce normal growth in mutant
dwarf plants?
a. IAA
b. cytokinin
c. gibberellin
d. abscisic acid
e. ethylene
Biological clocks cause organisms to perform
daily activities on a regular basis. Which of the
following is a FALSE statement about this kind
of “circadian rhythm”?
a. It may have the same signal-transduction
pathway in all organisms.
b. It must be reset on a daily basis.
c. It may help to cause photoperiod
responses.
d. It is independent of day and night length.
As flowers develop, which of the following
transitions occur?
a. The microspores become pollen grains.
b. The ovary becomes a fruit.
c. The petals are discarded.
d. The ovules become seeds.
e. All of these are correct.
The gametophyte is the dominant generation
in which of the following plants?
a. dicots
b. monocots
c. gymnosperms
d. ferns
e. mosses
Which of the following is mismatched?
a. polar nuclei- plumule
b. egg and sperm- zygote
c. ovule- seed
d. ovary- fruit
Phytochrome
a. is a plant pigment.
b. is present as Pfr during the day.
c. activates regulatory proteins.
d. all of these