Question 1

The direction of a nastic movement is always ______ the direction of the stimulus.

Accepted Answer

A)  away from
B)  toward
C)  at right angles to
D)  at an oblique angle to
E)  independent of

Question 2

In nyctinastic movements, leaves:

Accepted Answer

A)  twine around a support such as a fence post.
B)  have their stomata open during the night and closed during the day.
C)  are rolled during the day and unrolled at night.
D)  are oriented vertically in darkness and horizontally in light.
E)  are oriented horizontally in darkness and vertically in light.

Question 3

Which of the following statements about circadian clocks is FALSE?

Accepted Answer

A)  Input pathways and output pathways are the parts of the clock that do not interact.
B)  Conceptually they consist of three parts.
C)  They cause the regular oscillation of 30-40 percent of Arabidopsis genes.
D)  The central oscillator is the part of the clock that generates rhythmic behavior.
E)  Input pathways are the part of the clock that carries information to the oscillator.

Question 4

In the process of vernalization, early ______ is stimulated by exposing the germinating seeds to ______ temperatures.

Accepted Answer

A)  dormancy; low
B)  flowering; low
C)  germination; low
D)  dormancy; high
E)  germination; high

Question 5

The seismonastic movements of Mimosa pudica involve changes in the pulvini.

Accepted Answer

A) True 
 B)False

Question 6

With respect to effect on flowering, the middle of the dark period is the part most sensitive to interruption by a flash of light.

Accepted Answer

A) True 
 B)False

Question 7

According to the original hypothesis on negative gravitropism of shoots, auxin is redistributed to the ______ side where it ______ cell expansion.

Accepted Answer

A)  lower; stimulates
B)  lower; inhibits
C)  upper; stimulates
D)  upper; inhibits
E)  upper; first inhibits then stimulates

Question 8

The sleep movements of plants are an example of nastic movements.

Accepted Answer

A) True 
 B)False

Question 9

The florigen FT is produced in:

Accepted Answer

A)  vessel elements.
B)  companion cells.
C)  tracheids.
D)  sieve-tube elements.
E)  guard cells.

Question 10

The rapid closure of leaves of the Venus flytrap is now thought to be due to:

Accepted Answer

A)  changes in turgor pressure in the cells beneath the epidermis.
B)  changes in turgor pressure in the upper epidermis.
C)  changes in turgor pressure in cells of the pulvinus.
D)  acid-induced wall loosening of motor cells.
E)  unloading of sucrose from the phloem.

Question 11

The ageotropum mutant of pea plants lacks both a hydrotropic response and a gravitropic response.

Accepted Answer

A) True 
 B)False

Question 12

Which of the following statements about bud scales is FALSE?

Accepted Answer

A)  They may contain growth inhibitors.
B)  They protect the bud against desiccation.
C)  They restrict the movement of oxygen into the bud.
D)  They insulate the bud from heat loss.
E)  They have leaf primordia in their axils.

Question 13

In the current model of root gravitropism, elongation is _____ in the upper side of the distal elongation zone and ______ along the lower side.

Accepted Answer

A)  stimulated; stimulated
B)  stimulated; suppressed
C)  suppressed; stimulated
D)  suppressed; is neither stimulated nor suppressed
E)  is neither stimulated nor suppressed; suppressed

Question 14

Stratification is the process used by horticulturalists in which seeds are:

Accepted Answer

A)  moistened and exposed to low temperature.
B)  moistened and exposed to high temperature.
C)  mechanically abraded.
D)  soaked in alcohol.
E)  dried.

Question 15

Regular rubbing or bending of a stem stimulates its elongation.

Accepted Answer

A) True 
 B)False

Question 16

Experiments on cocklebur have shown that the ______ perceives the photoperiod.

Accepted Answer

A)  apical meristem
B)  columella
C)  leaf blade
D)  petiole
E)  stem

Question 17

Vernalization is the exposure of flower buds to low temperatures to promote early flowering.

Accepted Answer

A) True 
 B)False

Question 18

Which of the following statements concerning photoperiodism is FALSE?

Accepted Answer

A)  Short-day plants in the early spring or fall.
B)  Spinach and lettuce are examples of long-day plants.
C)  Day-neutral plants flower without respect to photoperiod.
D)  Photoperiodic behavior remains constant over a wide range of temperatures.
E)  In some plants, only a single exposure to the critical day-length will produce a response.

Question 19

Photoperiodism pertains to events that are influenced by the relative lengths of light and dark.

Accepted Answer

A) True 
 B)False

Question 20

In contrast to thigmonastic movements, thigmomorphogenesis:

Accepted Answer

A)  is a response to touch.
B)  is a response to a mechanical stimulus.
C)  is independent of the direction of the stimulus.
D)  involves cells of the pulvinus.
E)  involves an altered growth pattern.

Exam 28: External Factors and Plant Growth

Which of the following statements concerning photoperiodism is FALSE?

Correct AnswerverifiedShow Answer

According to the original hypothesis on negative gravitropism of shoots, auxin is redistributed to the ______ side where it ______ cell expansion.

Correct AnswerverifiedShow Answer

With respect to effect on flowering, the middle of the dark period is the part most sensitive to interruption by a flash of light.

Correct AnswerverifiedShow Answer

In nyctinastic movements, leaves:

Correct AnswerverifiedShow Answer

The rapid closure of leaves of the Venus flytrap is now thought to be due to:

Correct AnswerverifiedShow Answer

The direction of a nastic movement is always ______ the direction of the stimulus.

Correct AnswerverifiedShow Answer

The sleep movements of plants are an example of nastic movements.

Correct AnswerverifiedShow Answer

Vernalization is the exposure of flower buds to low temperatures to promote early flowering.

Correct AnswerverifiedShow Answer

Experiments on cocklebur have shown that the ______ perceives the photoperiod.

Correct AnswerverifiedShow Answer

Regular rubbing or bending of a stem stimulates its elongation.

Correct AnswerverifiedShow Answer

The seismonastic movements of Mimosa pudica involve changes in the pulvini.

Correct AnswerverifiedShow Answer

In the current model of root gravitropism, elongation is _____ in the upper side of the distal elongation zone and ______ along the lower side.

Correct AnswerverifiedShow Answer

Photoperiodism pertains to events that are influenced by the relative lengths of light and dark.

Correct AnswerverifiedShow Answer

Which of the following statements about bud scales is FALSE?

Correct AnswerverifiedShow Answer

The ageotropum mutant of pea plants lacks both a hydrotropic response and a gravitropic response.

Correct AnswerverifiedShow Answer

Which of the following statements about circadian clocks is FALSE?

Correct AnswerverifiedShow Answer

In the process of vernalization, early ______ is stimulated by exposing the germinating seeds to ______ temperatures.

Correct AnswerverifiedShow Answer

In contrast to thigmonastic movements, thigmomorphogenesis:

Correct AnswerverifiedShow Answer

The florigen FT is produced in:

Correct AnswerverifiedShow Answer

Stratification is the process used by horticulturalists in which seeds are:

Correct AnswerverifiedShow Answer

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According to the original hypothesis on negative gravitropism of shoots, auxin is redistributed to the side where it cell expansion.

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In the current model of root gravitropism, elongation is _ in the upper side of the distal elongation zone and __ along the lower side.

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In the process of vernalization, early is stimulated by exposing the germinating seeds to temperatures.

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