1. All of the following may directly function in a signal transduction pathway in plants EXCEPT...
A.calcium ions.
B.turgor pressure.
C.receptor proteins.
D.phytochrome.
E.second messengers.
B.turgor pressure.
2. According to modern ideas about phototropism in plants...
A.light causes auxin to accumulate on the shaded side of a plant stem.
B.auxin stimulates elongation of plant stem cells.
C.auxin is produced by the tip of the coleoptile and moves downward.
D.A
XXX light causes auxin to accumulate on the shaded side of a plant stem.
3. The apical bud of a pine tree inhibits the growth of lateral buds through the production of...
A.abscisic acid.
B.acid growth.
C.cytokinin.
D.gibberellin.
E.auxin.
E.auxin.
4. 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)
D.ethylene
5. Which of the following statements about plant hormones is FALSE?
A.The growth of plants in nature is probably regulated by a combination of growth-stimulating and growth-inhibiting hormones.
B.Abscisic acid generally promotes growth.
C.Gibberellins sti
B.Abscisic acid generally promotes growth.
6. 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.ABA
B.indoleacetic acid
C.gibberellin
D.cytokinin
E.abscisic acid
D.cytokinin
7. 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.both A and B
E.B and C only
D.both A and B
8. 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 r
D.auxin can stimulate cell elongation in apical meristems, yet will inhibit the growth of axillary buds.
9. 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?
A.Auxin binds to different receptors in differen
C.Auxin causes second messengers to activate both proton pumps and certain genes.
10. 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
D.increasing wall plasticity and allowing the affected cell walls to elongate.
11. 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.the establishment of circadian rhythms.
C.phototropism.
12. What do 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
B.The effect of a plant hormone can depend on the tissue.
13. Regarding positive gravitropism exhibited by plant roots...
A.it is mediated by auxin as for phototropism.
B.it depends on more rapid elongation of some cells than other cells.
C.gravity causes auxins to accumulate on the lower side of roots.
D.the ph
XXX it is mediated by auxin as for phototropism XXX
14. 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.
E.increasing cytoplasmic levels of specific solute concentrations, such as sugars.
15. All of the following are responses of plants to cold stress EXCEPT...
A.the production of a specific solute "plant antifreeze" that reduces water loss.
B.excluding ice crystals from the interior walls.
C.conversion of the fluid mosaic cell membrane to
C.conversion of the fluid mosaic cell membrane to a solid mosaic one.
16. In general, which of the following is NOT a plant response to herbivores?
A.domestication, so that humans can protect the plant
B.attracting predatory animals, such as parasitoid wasps
C.chemical defenses, such as toxic compounds
D.physical defenses,
A.domestication, so that humans can protect the plant
17. 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
B.phytoalexins
18. 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
D.if it has the specific R gene that corresponds to the pathogen molecule encoded by an Avr gene.
19. The rapid leaf movements resulting from a response to touch (thigmotropism) involve transmission of electrical impulses called action potentials.
A.True
B.False
A.True
20. Systemic acquired resistance is a generalized plant defense response in organs distant from the infection site.
A.True
B.False
A.True