CHAPTER 37—PLANT SIGNALS AND RESPONSES TO THE ENVIRONMENT
MULTIPLE CHOICE
1. Creosote bush clusters have been shown to be descendant from single seeds that germinated
a.
in mesic environments.
b.
9,000 to 11,000 years ago.
c.
from asexual reproduction.
d.
from a drought intolerant genotype.
e.
after being ingested by herbivores and deposited in feces.
2. Which of the following is NOT known to be influenced by plant hormones?
a.
patterns of plant growth
b.
plant cell metabolism
c.
plant gene expression
d.
plant growth responses to light
e.
plant extinction rates
3. Plant hormones generally ____ concentrations to be effective, and usually have ____ on different plant
tissues.
a.
are effective only in extremely large; the same effect
b.
require only low; different effects
c.
require only low; the same effect
d.
are effective only in extremely large; different effects
e.
require moderate; the same effect
4. Which of the following is the most important natural auxin?
a.
abscisic acid
b.
gibberellic acid
c.
jasmonic acid
d.
indoleacetic acid
e.
salicylic acid
5. Work by Charles Darwin and Francis Darwin was instrumental in the discovery of which type of plant
hormone?
a.
auxins
b.
brassinosteroids
c.
jasmonates
d.
cytokinins
e.
gibberellins
6. Darwin’s experiments on phototropism illustrated that
a.
plant stems bend away from bright lights.
b.
signals from plant roots control phototropism.
c.
an opaque cap placed over a shoot tip will cause a plant to bend toward light, but will
inhibit growth.
d.
a translucent cap placed over a shoot tip will cause a plant to bend toward light, but will
inhibit growth.
e.
a translucent cap placed over a shoot tip will cause a plant to both grow and bend toward
light.
7. Which type of plant hormone is primarily responsible for the bending of a plant shoot toward light?
a.
auxins
b.
ethylene
c.
systemin
d.
salicylic acid
e.
brassinosteroids
8. The growth-promoting substance that promotes stem elongation and bending toward light is produced
primarily in
a.
root tips, traveling to the stem in the xylem.
b.
the center of the stem region where elongation or bending occurs.
c.
flowers and flower buds.
d.
the shoot tip.
e.
root tips, traveling to the stem in the phloem.
9. Which of the following should prevent a grass seedling shoot from bending toward light?
a.
removing the shoot tip
b.
placing a translucent cap on the shoot tip
c.
placing an opaque cap on the shoot tip
d.
either removing the shoot tip or placing a translucent cap on the shoot tip
e.
either removing the shoot tip or placing an opaque cap on the shoot tip
10. Which type of plant hormone is primarily responsible for inhibiting growth of lateral meristems on
shoots and restricting the formation of branches?
a.
abscisic acid
b.
cytokinins
c.
auxins
d.
salicylic acid
e.
gibberellins
11. Trimming a shrub will make it become more bushy (have more lateral growth) primarily due to a
reduction in the amount of ____.
a.
auxin
b.
ethylene
c.
abscisic acid
d.
gibberellin
e.
cytokinin
12. Imagine that you want all of the orange trees in your orchard to uniformly flower and set fruit. Which
type of plant hormone should you spray on your plants?
a.
brassinosteroids
b.
auxins
c.
ethylene
d.
salicylic acid
e.
cytokinins
13. Which type of plant hormone is primarily responsible for inhibiting leaf abscission?
a.
gibberellins
b.
ethylene
c.
jasmonates
d.
abscisic acid
e.
auxins
14. Which type of plant hormone is primarily responsible for promoting the formation of lateral roots?
a.
jasmonates
b.
gibberellins
c.
auxins
d.
systemin
e.
cytokinins
15. The most widely used herbicide in the world, 2,4-D, is a synthetic form of
a.
abscisic acid.
b.
ethylene.
c.
salicylic acid.
d.
gibberellin.
e.
auxin.
16. Movement of IAA in a shoot tip is as follows:
a.
IAA initially moves downward from the shoot tip via polar transport.
b.
IAA initially moves laterally from the shaded to illuminated side of the shoot tip.
c.
IAA initially moves laterally from the illuminated to shaded side of the shoot tip.
d.
IAA initially moves laterally in the shoot tip via non-polar transport.
e.
IAA moves from root tips upwards towards leaves.
17. An agar block filled with auxin is placed on top of a shoot that has had the shoot tip removed. The agar
block is placed so that it covers only one side of the top of the shoot. Which of the following should
occur?
a.
The shoot will stop growing.
b.
The shoot will grow faster on the side away from the agar block.
c.
The shoot will grow straight up.
d.
The shoot will grow faster on the side with the agar block.
e.
The shoot will grow faster on both the side away from the agar block and on the side with
agar block.
18. According to the acid-growth hypothesis, auxin causes increased acidity in cell walls, which then
activates ____ that disrupt(s) bonds between cellulose microfibrils, allowing cell expansion.
a.
a membrane potential
b.
AUX1 transporters
c.
proteins called expansins
d.
an mRNA
e.
K+ ions
19. Where is the auxin receptor ABP1 located in plant cells?
a.
cell wall
b.
cytoplasm
c.
endoplasmic reticulum
d.
plasma membrane
e.
nucleus
20. Which type of plant hormone is primarily responsible for helping break the dormancy of seeds and
buds?
a.
gibberellins
b.
cytokinins
c.
ethylene
d.
auxins
e.
jasmonates
21. Which type of plant hormone would be used by commercial grape growers to get larger grapes by
lengthening the stem on which fruits develop?
a.
abscisic acid
b.
ethylene
c.
auxins
d.
salicylic acid
e.
gibberellins
22. A pea plant that is not able to make GA1 will
a.
grow away from light.
b.
not be able to make flowers.
c.
be a dwarf.
d.
not be able to make fruits.
e.
have nearly no root growth.
23. Which type of plant hormone is primarily responsible for the growth of a floral stalk in rosette plants
such as cabbages?
a.
salicylic acid
b.
cytokinins
c.
ethylene
d.
gibberellins
e.
brassinosteroids
24. In monoecious species of plants, plants that have separate “male” and “female” flowers both on the
same plant, applications of gibberellin
a.
cause all flowers formed to be “female”.
b.
encourage proportionally more “male” flowers to develop.
c.
cause all flowers formed to actually be both “male” and “female“.
d.
cause all flowers formed to be “male”.
e.
encourage proportionally more “female” flowers to develop.
25. Which type of plant hormone was first discovered in experiments to define the nutrient media required
for plant tissue culture?
a.
gibberellins
b.
cytokinins
c.
salicylic acid
d.
auxins
e.
brassinosteroids
26. Which type of plant hormone can be produced by boiling DNA?
a.
salicylic acid
b.
auxins
c.
cytokinins
d.
abscisic acid
e.
jasmonates
27. Which type of plant hormone is structurally similar to adenine?
a.
brassinosteroid
b.
abscisic acid
c.
ethylene
d.
cytokinin
e.
systemin
28. Which type of plant hormone is synthesized mainly in root tips and is apparently transported through
the plant in xylem sap?
a.
gibberellins
b.
auxins
c.
oligosaccharins
d.
ethylene
e.
cytokinins
29. Which type of plant hormone causes chloroplasts to mature?
a.
cytokinins
b.
salicylic acid
c.
abscisic acid
d.
ethylene
e.
gibberellins
30. Suppose you are culturing tobacco in a petri dish at a 10:1 ratio of auxin to cytokinin. To promote only
shoot development you would
a.
increase the cytokinin ratio
b.
increase the auxin ratio
c.
reduce the auxin level significantly and increase the cytokinin level slightly
d.
grow the tobacco in the dark
e.
grow the tobacco in the light
31. Which type of plant hormone retards leaf aging?
a.
salicylic acid
b.
abscisic acid
c.
cytokinins
d.
ethylene
e.
gibberellins
32. In tobacco tissue culture, getting both roots and shoots to develop requires
a.
an auxin-to-cytokinin ratio of 10:1.
b.
a higher concentration of cytokinin than auxin.
c.
an auxin-to-cytokinin ratio of slightly greater than 10:1.
d.
an intermediate auxin-to-cytokinin ratio.
e.
exactly equal amounts of auxin and cytokinin.
33. Synthetic compounds similar to which type of plant hormone are used to prolong the shelf life of
vegetables such as lettuces and mushrooms and to keep cut flowers fresh?
a.
salicylic acid
b.
jasmonates
c.
abscisic acid
d.
gibberellins
e.
cytokinins
34. Which type of plant hormone is a gas at normal temperature and pressure?
a.
abscisic acid
b.
ethylene
c.
auxin
d.
salicylic acid
e.
systemin
35. Which type of plant hormone governs senescence in plants, such as the loss of leaves in autumn by
some plants?
a.
cytokinins
b.
abscisic acid
c.
gibberellins
d.
brassinosteroids
e.
ethylene
36. Which type of plant hormone promotes fruit ripening?
a.
ethylene
b.
jasmonates
c.
gibberellins
d.
brassinosteroids
e.
abscisic acid
37. Placing a ripe apple with other apples that are not ripe will cause the other apples to ripen sooner.
Which type of plant hormone is responsible for this effect?
a.
brassinosteroids
b.
ethylene
c.
auxins
d.
oligosaccharins
e.
abscisic acid
38. Which type of plant hormone has been shown to both promote pollen tube elongation and inhibit root
elongation?
a.
jasmonates
b.
ethylene
c.
brassinosteroids
d.
salicylic acid
e.
oligosaccharins
39. Which type of plant hormone was first isolated from the pollen of Brassica napus?
a.
auxins
b.
jasmonates
c.
gibberellins
d.
brassinosteroids
e.
oligosaccharins
40. Which of the following types of plant hormones appears to regulate the expression of genes associated
with a plant’s growth responses to light?
a.
salicylic acid
b.
brassinosteroids
c.
gibberellins
d.
jasmonates
e.
oligosaccharins
41. Which of the following types of plant hormones is apparently synthesized from carotenoid pigments
inside plastids?
a.
salicylic acid
b.
cytokinins
c.
abscisic acid
d.
jasmonates
e.
brassinosteroids
42. Which type of plant hormone is generally responsible for long-term inhibition of plant growth such as
in buds and seeds?
a.
auxins
b.
gibberellins
c.
oligosaccharins
d.
brassinosteroids
e.
abscisic acid
43. Imagine that you own a nursery and you want to reduce the chance that plants you ship will suffer
from shipping damage. Which type of plant hormone should you apply to the plants before shipping?
a.
cytokinins
b.
abscisic acid
c.
oligosaccharins
d.
gibberellins
e.
ethylene
44. Where are abscisic acid receptors located in plant cells?
a.
cell wall
b.
cytoplasm
c.
endoplasmic reticulum
d.
plasma membrane
e.
nucleus
45. Which type of plant hormone stimulates stomata to close during a drought?
a.
salicylic acid
b.
gibberellins
c.
abscisic acid
d.
auxins
e.
oligosaccharins
46. The second messenger inositol triphosphate (IP3) appears to be involved in stomatal closure triggered
by
a.
auxins.
b.
abscisic acid.
c.
oligosaccharins.
d.
salicylic acid.
e.
gibberellins.
47. Which of the following types of plant hormones triggers plant responses to environmental stresses
such as cold snaps, high salinity, and drought?
a.
abscisic acid
b.
cytokinins
c.
oligosaccharins
d.
jasmonates
e.
ethylene
48. Which type of plant signaling compound is produced from structural elements of the cell wall?
a.
salicylic acid
b.
oligosaccharins
c.
abscisic acid
d.
auxins
e.
brassinosteroids