Biology

what would happen if the secondary messenger cGMP was blocked in the de-etiolation pathway?

Ca2+ channels could open, and specific protein kinase 2 could still be produced

which of these cncusions is supported by the research of both Went and Charles and Francis Darwin on shoot responses to light?

a chemical substance involved in shoot bending is produced in shoot tips

negative gravitropism of plant shoots

a, B, and C

we know from the experiments of the past that plants bend toward light because

cell expansion is greater on the dark side of the stem

this experiment suggests that the unknown amount of gibberellin in the experimental plant (B) is approximately

0.1 ug/mL

according to modern ideas about phototropism in plants

A, B, and C

plants growing in a partially dark environment will grow toward light in a response called phototropism. Choose the incorrect statement regarding phototropism

Auxin causes a decrease in growth on the side of the stem exposed to light

which of the following statements about plant hormones is false

abscisic acid generally promotes growth

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?

add some incandescent bulbs to increase the amount of red light

the biological clock controlling circadian rhythms must ultimately

affect gene transcription

which of the following is not presently considered a major mechanism whereby hormones control plant development?

affecting cell respiration via regulation of the citric acid cycle

ethylene, as an example of a plant hormone, may have multiple effects on a plant, depending on all of the following except the

altered chemical structure of ethylene from a gas to a liquid

one effect of gibberellins is to stimulate cereal seeds to produce

amylase

which of the following is currently the most powerful method of research on plant hormones

analyzing mutant plants

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

are more predictable than air temp changes

the apical bud of a pine tree inhibits the growth of lateral buds through the production of

auxin

plant hormones can have different effects at different concentrations. this explains how

auxin can stimulate cell elongation in apical meristems, yet will inhibit the growth of axillary buds

auxin triggers the acidification of cell walls that results in rapid growth, but also stimulates sustained, long-term cell elongation. what best explains how auxin brings about this dual growth response?

auxin causes second messengers to activate both proton pumps and certain genes

which of the following has not been established as an aspic of auxin's role in cell elongation

auxin increases the quantity of cytoplasm in the cell

a plant seedling bends toward sunlight bc

auxin is found in greatest abundance on the dark side of the stem

after some time, the tip of a plant that has been forced into a horizontal position grows upward. this phenomenon is related to

auxin movement toward the lower side of the stem

why do coleoptiles grow toward light

auxin moves away from the light to the shady side

cells elongate in response to auxin. all of the following are part of the acid growth hypothesis except

auxin-activated proton pumps stimulate cell division in meristems

which of the following hormones would be most useful in promoting the rooting of plant cuttings?

auxins

which plant hormones might be used to enhance stem elongation and fruit growth

auxins and gibberellins

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?

blue

plant hormones produce their effects by

both A and B

why might animal hormones function differently from plant hormones?

both A and D are correct

external stimuli would be received most quickly by a plant cell if the receptors for signal transduction were located in the

cell membrane

when growing plants in culture, IAA is used to stimulate cel enlargement. which plant growth regulator has to now be added to stimulate cell division?

cytokinin

which plant hormone(s) is (are) most closely associated with cell division?

cytokinin

buds and sprouts often form on tree stumps. which of the following hormones would you expect to stimulate their formation?

cytokinis

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?

ethylene

the plant hormone involved in aging and ripening of fruit is

ethylene

the ripening of fruit and the dropping of leaves and fruit are principally controlled by

ethylene

which of the following does not reduce the level of the Pfr form of phytochrome?

exposure to red light

we tend to think of plants as immobile, when, in fact, they can move in many ways. all of the following are movements plants can accomplish except

folding and unfolding of leaves using muscle-like tissues

plant growth regulators can be characterized by all of the following except that they

function independently of other hormones

in attempting to make a seed break dormancy, one logically could treat it with

gibberllins

the synthesis of which of the following hormones would be a logical first choice in an attempt to produce normal growth in mutant ward plants?

giberellin

evidence for phototropism due to the asymmetric distribution of auxin moving down the stem

has not been found in eudicots such as sunflower and radish

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

have no effect upon flowering

according to the acid growth hypothesis, auxin works by

increasing wall plasticity and allowing the affected cell walls to elongate

which one of the following is not a direct function of either auxin or gibberellin

inducing senescence and ripening

many plants flower in response to day-length cues. which statement concerning flowering is false

long-day plants flower in response to long days, not short nights

auxins (IAA) in plants are known to affect all of the following phenomena except

maintenance of dormancy

a short-day plant will flower only when

nights are longer than a certain critical value

All of the following may function in signal transduction in plants except

non random mutations

biologic 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"?

once set, it is independent of external signals

incandescent light bulbs, which have high output of red light, are least effective in promoting

phototropism

if protein synthesis was blocked in etiolated cells, what would be necessary for the "greening" of these cells?

post-translational modification of existing proteins

how does indoleacetic acid affect fruit development?

promoting rapid growth of the ovary

in legumes, it has been shown hat "Sleep" movements are correlated with

rhythmic opening and closing of K+ channels in motor cell membranes

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

seeds require light to germinate

both red and blue light are involved in

stem elongation

auxin is responsible for all of the following plant growth responses except

the detection of photperiod

oat seedlings are sometimes used to study auxins because

their coleptile exhibits a strong positive phototropism

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

tip of the coleoptile