Question 1

Which of the following is not involved in the acid growth hypothesis for the regulation of cell expansion by auxin?

Accepted Answer

A)  Pumping of protons into the apoplast 
B)  Pumping of protons into the cytosol 
C)  Increased expression of the proton pump gene 
D)  Increased insertion of proton pumps into the plasma membrane 
E)  Loosening and expansion of the cell wall

Question 2

Refer to the figure below showing a signal reception pathway.  What happens when the relevant hormone (e.g., auxin or gibberellin) is absent?

Accepted Answer

A)  The repressor protein prevents transcription of growth promoting genes. 
B)  The addition of ubiquitin to the repressor is stimulated. 
C)  The repressor protein is broken down in the proteasome. 
D)  Genes for the relevant hormone are transcribed. 
E)  The relevant hormone is produced in the cytoplasm of cell.

Question 3

A researcher studying a seedling can determine its stage of development according to the molecular phenomena that are occurring.If DNA synthesis is observed, the seedling is at the stage at which

Accepted Answer

A)  gibberellins are secreted by the embryo. 
B)  the embryonic root, or radicle, begins to grow. 
C)  imbibition takes place. 
D)  the endosperm starts metabolizing starches, proteins, and lipids. 
E)  the aleurone layer assembles enzymes, proteases, and ribonucleases.

Question 4

Bean plants raise their leaves during the day and lower them at night.Explain what might happen to a plant if this circadian response were disrupted.

Accepted Answer

The answer of Bean plants raise their leaves during the...

Question 5

Which is not an effect of cytokinins or auxins?

Accepted Answer

A)  Formation of shoot buds 
B)  Formation of roots 
C)  Growth of fruit 
D)  Cell division 
E)  Leaf abscission

Question 6

An unripe lemon that is placed in a paper bag with an apple will ripen; its skin will yellow, it will soften, and it will produce the characteristic lemon odor.Which plant hormone released by the apple causes this effect?

Accepted Answer

A)  Auxin 
B)  Ethylene 
C)  Cytokinins 
D)  Gibberellins 
E)  Abscisic acid

Question 7

The dormancy of seeds is one reason that seed plants are such successful life forms.How does light affect seed germination?

Accepted Answer

A)  Light inhibits seed germination in most plant species. 
B)  Light would most likely inhibit the germination of seeds with few food reserves. 
C)  Light would most likely stimulate the germination of seeds with large food reserves. 
D)  Light can either inhibit or enhance seed germination, depending on the species. 
E)  Light stimulates the germination of most seeds.

Question 8

The gibberellin signal transduction pathway leads to

Accepted Answer

A)  breakdown of proteins to allow for gene expression. 
B)  inactivation of growth-stimulating genes. 
C)  inactivation of proteases. 
D)  inhibition of the polyubiquitination of repressor proteins. 
E)  conversion of phytochrome Pr to phytochrome Pfr.

Question 9

Evidence that gibberellins are produced by plants was gathered in studies with dwarf mutant strains of tomato.Work on dwarf peas produced the same results: treatment with gibberellins caused the dwarf plants to _______, while the normal, tall plants _______.

Accepted Answer

A)  grow taller; also grew taller, but only slightly 
B)  grow taller; were virtually unaffected 
C)  stop growing immediately; stopped growing after a period of time 
D)  stop growing; were virtually unaffected 
E)  die; stopped growing

Question 10

Cytokinins and ethylene have opposite effects on

Accepted Answer

A)  leaf senescence. 
B)  maintenance of the apical hook in dicot seedlings. 
C)  elongation of stems. 
D)  lateral swelling of stems. 
E)  winter dormancy.

Question 11

Which of the following statements about plant tropisms is true?

Accepted Answer

A)  An imbalance in gibberellin concentration causes curvature. 
B)  Roots grow toward the light. 
C)  One side of the root or shoot grows more rapidly than the other in response to differences in the amount of auxin present. 
D)  DNA is the light receptor or gravity receptor. 
E)  Auxin is the light receptor or gravity receptor.

Question 12

Refer to the diagram below showing cereal grain germination.  Which layer of the grain produces hydrolytic enzymes during germination?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 13

Suppose that seedless raspberries have been discovered in a genetic screen and commercialized.What plant hormone could be added to the developing fruits so they will grow to the normal size of seeded fruits?

Accepted Answer

A)  Cytokinins 
B)  Nitrous oxide 
C)  Ethylene 
D)  Abscisic acid 
E)  Gibberellins

Question 14

Plant primary roots typically grow into the ground by responding to the directional signal of gravity.If you wanted to identify a plant that had a mutation in its gravity signal transduction pathway, which of the following methods would be most useful?

Accepted Answer

A)  Growing a batch of seeds in zero-gravity conditions and then collecting any seedlings with primary roots that are growing in different directions 
B)  Treating a batch of seeds with a mutagen, placing each germinating seed on the soil with the primary roots emerging in a different direction, and collecting any plants with primary roots that grow into the soil 
C)  Treating a batch of seeds with a mutagen, growing them alongside wild-type seeds, and collecting any seedlings with primary roots growing longer than the wild-type roots 
D)  Growing a batch of seeds in zero-gravity conditions and then collecting any seedlings with primary roots that are growing toward the ground 
E)  Treating a batch of seeds with a mutagen, growing them alongside wild-type seeds, and collecting any seedlings with primary roots growing in a direction that is different from that of the wild-type roots

Question 15

Plant hormones can work in pairs, with one hormone promoting a phenomenon and another inhibiting it.Which pair of hormones has opposing effects on senescence, with the stimulant listed first and the inhibitor listed second?

Accepted Answer

A)  Cytokinin and abscisic acid 
B)  Auxin and gibberellins 
C)  Ethylene and auxin 
D)  Brassinosteroids and auxin 
E)  Ethylene and cytokinin

Question 16

Which of the following methods is most useful for studying plant signal transduction pathways?

Accepted Answer

A)  Genetic screens of mutants 
B)  Extensive field tests 
C)  Careful analysis of seeds 
D)  Extensive planting programs 
E)  Data collection in the wild

Question 17

Compare the early stages of shoot growth (following seed germination) in a rice, wheat, or corn plant compared to a typical eudicot such as a dandelion.

Accepted Answer

The answer of Compare the early stages of shoot growth...

Question 18

The discovery of auxin can be traced back to the work of Charles and Francis Darwin and their studies of

Accepted Answer

A)  photosynthesis. 
B)  photorespiration. 
C)  photophosphorylation. 
D)  phototropism. 
E)  photoperiodism.

Question 19

_______ is the state in which a seed cannot germinate (even when dormancy is broken) due to unfavorable environmental conditions.

Accepted Answer

The answer of _______ is the state in which a...

Question 20

Refer to the diagram below showing cereal grain germination.  Explain what is happening with the hormones labeled "E" in step 2.

Accepted Answer

The answer of Refer to the diagram below showing cereal...

Exam 36: Regulation of Plant Growth