Question 1

The plant hormones known as ___________ may have an evolutionary origin in the common ancestor to both plants and animals.

Accepted Answer

A)  brassinosteroids
B)  oligosaccharides
C)  cytokinins
D)  auxins A

Question 2

When seeds are removed from strawberries, fruit growth is stopped.This suggests the seeds contain which of the following hormones?

Accepted Answer

A)  ethylene
B)  auxin
C)  strigolactones
D)  oligosaccharides B

Question 3

When gibberellin binds to its receptor, what happens to activate the gibberellin-dependent transcription factor GA-TRXN?

Accepted Answer

A)  Ethylene is released.
B)  A ubiquitin tag is used to degrade the GA-TRXN inhibitor.
C)  A DELLA protein is degraded, freeing the GA-TRXN.
D)  A DELLA protein is attached to GA-TRXN to activate it. C

Question 4

Which cell structure is most likely responsible for sensing gravity?

Accepted Answer

A)  central vacuole
B)  Golgi appartus
C)  chloroplast
D)  amyloplast

Question 5

While flipping through an agriculture products catalog, you come across the following advertisment, "The Centralized Ripening System-makes large scale hormone distribution even easier!".What hormone does this product distribute?

Accepted Answer

A)  auxin
B)  abscisic acid
C)  cytokinin
D)  ethylene

Question 6

Abscisic acid synthesized in the root travels to different parts of the shoot where it regulates transpirational water loss.What is the most likely way that ABA travels from the root to the various locations within the shoot?

Accepted Answer

A)  vessels and tracheids
B)  sieve tubes
C)  between cell walls
D)  from cell to cell through the plasmodesmata

Question 7

While researching the effects of light on chlorophyll synthesis in sorghum, you find that brief pulses of red light stimulates the synthesis of chlorophyll and This would suggest that chlorophyll synthesis is directed by the Pr form of phytochrome.

Accepted Answer

A) True 
 B)False

Question 8

What happens when coleoptiles are illuminated with directional light from the side instead of from directly overhead?

Accepted Answer

A)  More auxin is produced.
B)  Less auxin is produced.
C)  Auxin is transported away from the lighted side.
D)  Auxin is transported toward the lighted side.

Question 9

When Darwin covered the tip of a grass seedling with metal foil and then illuminated it from one side, what happened to the seedling?

Accepted Answer

A)  It bent away from the directional light.
B)  It did not respond to the directional light.
C)  It grew toward the light, as expected.
D)  It waved back and forth.

Question 10

Directional, light-triggered plant development is known as

Accepted Answer

A)  thigmotropism.
B)  phototropism.
C)  thigmonasty.
D)  photomorphogenesis.

Question 11

Several scientists, including Charles and Francis Darwin, Frits Went and others, demonstrated that auxins caused stems to bend toward light in a series of elaborate experiments.Went was the researcher who finally determined that bending of the stem toward light was a result of which mechanism?

Accepted Answer

A)  Light caused a reduction in auxin concentration and a reduction in stem elongation on the lighted side of the plant stem, and thus a bending in the direction of the light.
B)  The transport of auxin to the shaded side of the plant stem stimulated stem elongation and a bending in the direction of the light.
C)  Auxin concentration was equal on both sides (lighted and shaded)  of the stem; however, the apical meristem responded to the presence of light.
D)  A combination of positive phototropism and a negative gravitropism.

Question 12

While touring a farm, the farmer tells you that she uses cytokinin to increase crop productivity.But, from biology class you know that cytokinin alone has no effect on parenchyma cells.What other substance is the farmer most likely using in conjunction with cytokinin?

Accepted Answer

A)  auxin
B)  abscisic acid
C)  strigolactones
D)  ethylene

Question 13

Which of the following describe a role that ethylene plays in plant physiology.Check all that apply.__X__ Retarding stem and root elongation.__X__ Hastening the ripening of fruit._____ Inhibition of leaf abscission.__X__ Inhibition of lateral bud growth.__X__ Accelerates the loss of damaged fruits.

Accepted Answer

The answer of Which of the following describe a role...

Question 14

Plants maintain higher levels of phytochrome at their growing tips where phytochrome plays important roles in growth responses to light.Phytochrome levels are also high in areas of the plant that are "greening".What does this suggest about the role of phytochrome in these "greening" zones?

Accepted Answer

A)  Phytochrome is absorbing green wavelengths of light.
B)  In these areas, phytochrome is the first step in the electron transport chain of photosynthesis.
C)  Phytochrome is facilitating the transcription and translation of photosynthesis related proteins.
D)  Phytochrome is facilitating the migration of chlorophyll pigments from other areas of the plant.

Question 15

Research has shown that cytokinin levels fluctuate seasonally in temperate plants.What season would you expect to see the lowest levels of cytokinins and why would this be adaptive?

Accepted Answer

A)  Spring, because lower levels of cytokinin allow auxin to promote rapid growth in stem height.This will allow the plant to compete effectively for sunlight.
B)  Summer, because lower levels of cytokinin would slow growth down and delay leaf aging.This will allow the plant to maximize the production of starch and increase it's sugar reserves.This will help ensure the plant's survival through Autumn and Winter.
C)  Autumn, because lower levels of cytokinin at this time of year will induce the production of ethylene.This will result in maturation of fruit and ensure effective seed dispersal before Winter.
D)  Winter, because lower levels of cytokinin will place buds into a dormant state.This will protect the underlying tissues from freezing until Spring.

Question 16

The removal of the root cap eliminates the ability of a root to respond to gravity.

Accepted Answer

A) True 
 B)False

Question 17

If temperatures suddenly rise 5 to 10º C, __________ proteins are produced to help stabilize other proteins.

Accepted Answer

A)  denatured
B)  photosensitive
C)  chilling
D)  heat shock

Question 18

Mature plants may become __________ in dry or cold seasons in order to survive long periods that are unfavorable for growth.

Accepted Answer

A)  dormant
B)  dehydrated
C)  photoperiodic
D)  thigmonastic

Question 19

A plant physiologist treats a leaf with abscisic acid and observes that the stomata close.What happened inside the guard cells during the experiment?

Accepted Answer

A)  Abscisic acid influences the movement of sodium ions out of the guard cells.
B)  Abscisic acid influences the movement of potassium ions out of the guard cells.
C)  Abscisic acid binds carbon dioxide and causes carbonate crystals to block the stomatal opening.
D)  Abscisic acid binds with auxins and induces water molecules to exit the guard cells.

Question 20

The directional growth response of plants to touch is called

Accepted Answer

A)  phototropism.
B)  gravitropism.
C)  thigmotropism.
D)  photoperiodism.

Exam 40: Sensory Systems in Plants