Which of the following is currently the most powerful method of research on plant hormones?
analyzing mutant plants
Which one of the following is considered to be an important plant hormone that helps plants cope with environmental stress?
What plant hormones might be used to enhance stem elongation and fruit growth?
auxins and gibberellins
Which one of the following describes a plant's response to heat stress?
production of heat-shock proteins and closing of stomata
Which of the following hormones, produced in the root tips, is (are) required for normal growth?
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
Which of the following hormones would be most useful in promoting the rooting of plant cuttings?
Which of the following have accelerated recent discoveries about the function of plant hormones?
our increased knowledge of development using Arabidopsis, better analysis of signal transduction pathways using mutant plants, and more precise use of molecular biology techniques
Which of the following statements is (are) true of plants?
plants adjust their growth and development in response to environmental cues
Why is it so difficult to study the actions of plant hormones?
all of these make the study of plant hormones hard
When transplanting a tree, it is recommended to loosely attach three or four guylines. The purpose of leaving these supports loose is to
permit moderate bending to stimulate thickness growth
When phytochromes mediate plant reponses to shading they could cause
extension of shade leaves into the light
When an arborist prunes a lumb off a valuable tree, he usually paints the cut surface. The primary purpose of this is
to block entry of pathogens through the wound
When a plant that is not adapted to salty water is exposed to salty water it
will lose water rather than absorb it
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
What do results of research on gravitropic responses of roots and stems show?
the effect of a plant hormone can depend on the tissue
We know from the experiment of the past that plants bend toward light because
cell expansion is greater on the dark side of the stem
If a plant is mechanically stimulated, it will grow shorter, thicker stems. This response is
the result of ethylene production and an adaptation to windy environments
If you were shipping green bananas to a super market thousands of miles away, what chemical would you eliminate?
If you take a short-day plant and put it in a lab under conditinos where it will flower (long nights and short days), but interrupt its day period with a few minutes of darkness, what will happen?
it will flower
If a plant is bending towards the light, one would expect which enzymes to have increased activity?
Increasing the proportion of unsaturated fatty acids in their membranes is a response of plants to
In shoots, branching is inhibited by ____ from the tip of a growing shoot, but this effect is countered by ____ from the roots.
In the autumn, the amount of ____ increases and the amount of ____ decreases in leaf stalks causing a plant to drop fruit and leaves.
In a signal transduction pathway, the transduction stage amplifies the original signal by
having each receptor molecule produce multiple secondary messengers and having each secondary messenger activate numerous specific enzymes
In legumes, it has been shown that "sleep" movements are correlated with
rhythmic opening and closing of K+ channels in motor cells
In order for a plant to initiate a chemical response to herbivory
volatile signal compounds must be recieved
In extremely cold regions, woody species may survive freezing temperatures by
increasing cytoplasmic levels of specific solute concentrations, such as sugars
The results of this experiment, shown on the left of the graph (area A), may be used to
show a correlation between plant height and gibberellins concentration
The initial response of the root cells of a tomato plant watered with seawater would be to
begin to pasmolyze as water is lost
The immediate, direct effect of auxin in cell elongation, according to the acid growth hypothesis, is to
activate ATP-driven proton (H+) pumps
The houseplants in a windowless oom 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 plant hormone ethylene has three to four of the following characteristics. Which one, if any, of these features is NOT characteristic of ethylene?
ethylene has all of the above characteristics
The main reason seeds germinate when brought to the soil surface, when the soil is disturbed, might be because
they require light to germinate
The response to touch by such plants as the sensitive plant is due to
changes in water content of cells
The steps between a plant's perception of a change in the environment and the plants response to that change is best called
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?
This experiment suggests that the unknown amount of gibberellin in the experimental plant (B) is approximately (from figure 39.2)
Plant hormones can be characterized by all of the following except that they
function independently of other hormones
Plant hormones produce their effects by
altering the expression of genes and modifying the permeability of the plasma membrane
Plants are affected by an array of pathogens. Which of the following is not a plant defense against disease?
all of these are plant defenses against disease
Plants growing in a particularly dark environment will grow toward light in a response called phototropism. Choose the incorrect statement.
auxin causes a decrease in growth on the side of the stem exposed to light
Plant hormones can have different effects at different concentration. This explains how
auxin can stimulate cell elongation in apical meristems, yet will inhibit the growth of axillary buds
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 temperature changes
Plant roots that are in a horizontal position grown down because
cells on the upper side elongate more than those on the lower side
Auxin is responsible for all of the following plant growth responses except
detection of photoperiod
A pathogenic fungus invades a plant. What does the infected plant produce in response to the attack?
Alaskan trapper leaves lights on all the time. Plants flower a month early. They are
long day plants
All of the following are responses of plants to cold stress except
conversion of the fluid mosaic cell membrane to a solid mosaic one
A rapid loss of water in specialized cells in the sensitive plant mimosa pudica causes
leaves to droop
A certain short-day plant flowers when days are less than 12 hours long. Which of the following will cause it to flower?
a 13 hour night and an 11 hour day with 1 minute of darkness after 6 hours
A certain plant flowers only if days are shorter than 10 hours. Which of the following will cause it to flower?
8 hours light, 8 hours dark, flash of red light, flash of far-red light, 8 hours dark
A graduate student growing plant cells in a laboratory dish wants to see them ____ so the student treats them with cytokinins.
A chemical change in a substance called phytochrome
enables a plant to respond to the presence of light
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
falling statoliths trigger gravitropism
Some seeds require light for germination, which is controlled by the phytochrome system. In which of the following treatments would germination not occur?
red light followed by far-red light
Suppose there is a large deciduous ornamental tree on your campus and the city places a very bright street light right next to it on a tall pole. A botanist on the faculty complains to the city council and asks them to remove the light. Most likely the botanist is concerned because the light
may change the photoperiod and cause the tree to retain its leaves during the winter. This could cause dehydration and loss of the tree.
Short day plants are those that flower only when the night period of a plant is
longer than a defined period
One of the important roles of ethylene in plant development is that it induces radial swelling in:
root and stem seedling development
Certain plants may form tissues called ____ when their roots are flooded, whereas other plants may always form these tissue types.
Most scientists agree that global warming is underway; thus it is important to know how plants respond to heat stress. Which of the following is an immediate short-term response of plants to heat stress?
the production of heat-shock proteins like those of other organisms
External stimuli would be received most quickly by a plant cell if the receptors for signal transduction were located in the
How are halophytes adapted to salty environments?
they have salt glands that pump salt out of the plant across the leaf epidermis
How are heat-shock proteins thought to work?
they help other proteins retain their functional conformations
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?
There are larger intercellular spaces in the roots of the cypress than in the roots of the pine
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?
Once set, it is independent of external signals
You are interested in determining what part of a plant is actually sensitive to light for phototropism. A good first experiment would be to
Cover one part (for instance, the tip or base) before beginning light treatments
Which one of the following is most correct concerning plant behavior?
It is influenced by internal factors such as plant regulators.
Which of these conclusions is supported by the research of both Went and Charles and Frances Darwin on shoot responses to light?
A chemical substance involved in shoot bending is produced in shoot tips.
Plant cells begin synthesizing large quantities of heat-shock proteins
when the air around species from temperate regions is about 40 C
Certain plants that grow in environments where their roots are often under water need to provide ways of getting which of the following to the roots?
Which of the following has not been established as an aspect of auxin's role in cell elongation?
Auxin increases the quantity of cytoplasm in the cell.
abscisic acid is an important signal, transported from roots to the stem and leaves during times of water stress, that prevents:
A directional growth response that results in a change in the position of a plant is called
all the above
The plant hormone that prevents seed germination even if conditions of temperature and moisture conditions are appropriate would be:
If a short-day plant has a critical night length of 15 hours, then which of the following 24-hour cycles will prevent flowering?
8 hours light/8 hours dark/light flash/8 hours dark