Question 1

Phototropism is a phenomenon whereby

Accepted Answer

A)  a plant's growth is directed by light. 
B)  a plant's growth is dependent on light. 
C)  people living close to the poles become listless, depressed and sometimes aggressive due to deprivation of natural light. 
D)  plant growth is dependent on environmental factors. 
E)  all the animals in a food web eat plants. 
A)  a plant's growth is directed by light. 
B)  a plant's growth is dependent on light. 
C)  people living close to the poles become listless, depressed and sometimes aggressive due to deprivation of natural light. 
D)  plant growth is dependent on environmental factors. 
E)  all the animals in a food web eat plants. A

Question 2

The plant hormone auxin has many effects on plant growth EXCEPT

Accepted Answer

A)  it increases the respiration rate of the plant. 
B)  it increases the uptake of K+ ions by cells. 
C)  it increases the membrane potential of the cell. 
D)  it causes the uptake of hydrogen ions from the cell. 
E)  it stimulates the expression of new genes. 
A)  it increases the respiration rate of the plant. 
B)  it increases the uptake of K+ ions by cells. 
C)  it increases the membrane potential of the cell. 
D)  it causes the uptake of hydrogen ions from the cell. 
E)  it stimulates the expression of new genes. D

Question 3

At the end of a long day what is the relative level of CO and how does this in turn affect the expression of the FT gene and thus flowering?

Accepted Answer

A)  CO levels are high. CO binds to the FT promoter, initiating transcription and thus inhibiting flowering. 
B)  CO levels are high. CO binds to and inhibits FT expression, resulting in the inhibition of flowering. 
C)  CO levels are high. CO binds to and inhibits FT expression, resulting in the promotion of flowering. 
D)  CO levels are high. CO binds to the FT promoter, initiating transcription and thus promoting flowering. 
E)  CO levels are low. CO is displaced from its inhibiting position on the FT promoter, resulting in the promotion of flowering. 
A)  CO levels are high. CO binds to the FT promoter, initiating transcription and thus inhibiting flowering. 
B)  CO levels are high. CO binds to and inhibits FT expression, resulting in the inhibition of flowering. 
C)  CO levels are high. CO binds to and inhibits FT expression, resulting in the promotion of flowering. 
D)  CO levels are high. CO binds to the FT promoter, initiating transcription and thus promoting flowering. 
E)  CO levels are low. CO is displaced from its inhibiting position on the FT promoter, resulting in the promotion of flowering. D

Question 4

In young seedlings, the development of which organs is affected when expression of the auxin binding protein (ABP) is inhibited?

Accepted Answer

A)  Roots 
B)  Shoots 
C)  Cotyledons 
D)  Radicule 
E)  Both roots and shoots 
A)  Roots 
B)  Shoots 
C)  Cotyledons 
D)  Radicule 
E)  Both roots and shoots

Question 5

In which one of the following processes in plants is abscisic acid NOT involved?

Accepted Answer

A)  Drought resistance 
B)  Frost tolerance 
C)  Fruit ripening 
D)  Salinity tolerance 
E)  Closure of stomata 
A)  Drought resistance 
B)  Frost tolerance 
C)  Fruit ripening 
D)  Salinity tolerance 
E)  Closure of stomata

Question 6

During the vegetative phase of 'short day' plants, the interruption of the dark period with a ten-minute period of light will

Accepted Answer

A)  promote flowering. 
B)  have no effect. 
C)  cause etiolation of the stems. 
D)  inhibit growth at the apical bud. 
E)  negate the effect of the dark period. 
A)  promote flowering. 
B)  have no effect. 
C)  cause etiolation of the stems. 
D)  inhibit growth at the apical bud. 
E)  negate the effect of the dark period.

Question 7

In addition to stem elongation, gibberellins are thought to be involved in

Accepted Answer

A)  regulation of axillary bud growth. 
B)  apical dominance. 
C)  leaf senescence. 
D)  breaking seed dormancy and stimulating germination. 
E)  extensive root growth. 
A)  regulation of axillary bud growth. 
B)  apical dominance. 
C)  leaf senescence. 
D)  breaking seed dormancy and stimulating germination. 
E)  extensive root growth.

Question 8

The most important activity of abscisic acid is

Accepted Answer

A)  to enable plants to adapt to drought. 
B)  to activate a transcription factor by autophosphorylation. 
C)  to stimulate cell division in tissue culture. 
D)  to promote the growth of lateral buds into branches. 
E)  to enable plants to survive growth in swamp-like conditions. 
A)  to enable plants to adapt to drought. 
B)  to activate a transcription factor by autophosphorylation. 
C)  to stimulate cell division in tissue culture. 
D)  to promote the growth of lateral buds into branches. 
E)  to enable plants to survive growth in swamp-like conditions.

Question 9

IAA is thought to be involved in apical dominance through

Accepted Answer

A)  promoting the production of a growth-suppression factor. 
B)  promoting the growth of lateral buds. 
C)  promoting the growth of the apical bud. 
D)  diffusing down from the apical bud and inhibiting the growth of lateral buds. 
E)  All of the answers are correct. 
A)  promoting the production of a growth-suppression factor. 
B)  promoting the growth of lateral buds. 
C)  promoting the growth of the apical bud. 
D)  diffusing down from the apical bud and inhibiting the growth of lateral buds. 
E)  All of the answers are correct.

Question 10

The critical factor inducing flowering in plants is

Accepted Answer

A)  temperature. 
B)  time of sowing. 
C)  length of dark period. 
D)  length of sunlight. 
E)  Can be any of the answers. 
A)  temperature. 
B)  time of sowing. 
C)  length of dark period. 
D)  length of sunlight. 
E)  Can be any of the answers.

Question 11

What is the effective temperature range for plant to respond to vernalisation, and for how long will a plant typically need to be exposed to this temperature range?

Accepted Answer

A)  -1$\degree$C to 4$\degree$C for at least 4 weeks 
B)  1$\degree$C to 9$\degree$C for at least 3 weeks 
C)  -1$\degree$C to 9$\degree$C for at least 4 weeks 
D)  1$\degree$C to 9$\degree$C for at least 2 weeks 
E)  -1$\degree$C to 9$\degree$C for at least 6 weeks 
A)  -1$\degree$C to 4$\degree$C for at least 4 weeks 
B)  1$\degree$C to 9$\degree$C for at least 3 weeks 
C)  -1$\degree$C to 9$\degree$C for at least 4 weeks 
D)  1$\degree$C to 9$\degree$C for at least 2 weeks 
E)  -1$\degree$C to 9$\degree$C for at least 6 weeks

Question 12

Amyloplasts contain

Accepted Answer

A)  auxin. 
B)  plastids. 
C)  root cap cells. 
D)  starch granules. 
E)  gibberellin. 
A)  auxin. 
B)  plastids. 
C)  root cap cells. 
D)  starch granules. 
E)  gibberellin.

Question 13

Which of the following statements about ethylene is true?

Accepted Answer

A)  Its primary role is thought to be influencing plant responses to environmental stress. 
B)  Plants cannot grow without ethylene. 
C)  High auxin levels inhibit ethylene production. 
D)  Ethylene is used to retard ripening of stored fruit. 
E)  Ethylene production is controlled by cytokinin. 
A)  Its primary role is thought to be influencing plant responses to environmental stress. 
B)  Plants cannot grow without ethylene. 
C)  High auxin levels inhibit ethylene production. 
D)  Ethylene is used to retard ripening of stored fruit. 
E)  Ethylene production is controlled by cytokinin.

Question 14

Growth inhibitors in plants

Accepted Answer

A)  have a role in mediating the plants' response to stressful environments. 
B)  cause coleoptiles to bend away from light. 
C)  include zeatin and alpha amylase. 
D)  are essential for fruit ripening. 
E)  mediate positive geotropism. 
A)  have a role in mediating the plants' response to stressful environments. 
B)  cause coleoptiles to bend away from light. 
C)  include zeatin and alpha amylase. 
D)  are essential for fruit ripening. 
E)  mediate positive geotropism.

Question 15

IAA produces a phototropic response in plants

Accepted Answer

A)  by promoting an increase in the number of cells in a section of stem or coleoptile. 
B)  only when present in high concentrations in a section of stem or coleoptile. 
C)  by promoting cell elongation in a section of stem or coleoptile. 
D)  by promoting an increase in the number of cells and an elongation of the cells of the stem or coleoptile. 
E)  by increasing cell division in the apical tip. 
A)  by promoting an increase in the number of cells in a section of stem or coleoptile. 
B)  only when present in high concentrations in a section of stem or coleoptile. 
C)  by promoting cell elongation in a section of stem or coleoptile. 
D)  by promoting an increase in the number of cells and an elongation of the cells of the stem or coleoptile. 
E)  by increasing cell division in the apical tip.

Question 16

Short-day plants flower in response to a

Accepted Answer

A)  shortening of the photoperiod. 
B)  lengthening of the photoperiod. 
C)  lengthening of the dark period. 
D)  shortening of the dark period. 
E)  lengthening of day light. 
A)  shortening of the photoperiod. 
B)  lengthening of the photoperiod. 
C)  lengthening of the dark period. 
D)  shortening of the dark period. 
E)  lengthening of day light.

Question 17

What phenotype is associated with PIN1 mutants?

Accepted Answer

A)  Curled, needle-like leaves 
B)  Thin, elongated petioles 
C)  Naked, needle-like inflorescence stems 
D)  Thin, pointy roots devoid of lateral roots 
E)  Sepals and petals that are reduced in width such that they look thin and pointy 
A)  Curled, needle-like leaves 
B)  Thin, elongated petioles 
C)  Naked, needle-like inflorescence stems 
D)  Thin, pointy roots devoid of lateral roots 
E)  Sepals and petals that are reduced in width such that they look thin and pointy

Question 18

Ethylene affects plant growth by reacting with a receptor which is located in the

Accepted Answer

A)  nucleus, where it directly activates transcription factors. 
B)  plasma membrane where dimerisation causes autophosphorylation to initiate a signal transduction pathway. 
C)  intracellular as the ethylene may diffuse through the plasma membrane. 
D)  fruit, where it initiates ripening. 
E)  cytosol where it causes increased respiration. 
A)  nucleus, where it directly activates transcription factors. 
B)  plasma membrane where dimerisation causes autophosphorylation to initiate a signal transduction pathway. 
C)  intracellular as the ethylene may diffuse through the plasma membrane. 
D)  fruit, where it initiates ripening. 
E)  cytosol where it causes increased respiration.

Question 19

Plant growth responses are regulated by

Accepted Answer

A)  change in hormone levels. 
B)  changes in sensitivity of plant tissues to hormones. 
C)  environmental stimuli. 
D)  genetic factors. 
E)  All of the answers are correct. 
A)  change in hormone levels. 
B)  changes in sensitivity of plant tissues to hormones. 
C)  environmental stimuli. 
D)  genetic factors. 
E)  All of the answers are correct.

Question 20

It is hypothesised that auxin stimulates cell elongation, and therefore plant growth, by triggering the release of H+ inside cells and therefore acidifying the intracellular environment. What protein would need to be activated to achieve this, and where would it be located?

Accepted Answer

A)  ATPase proton pump in the tonoplast 
B)  ATPase proton pump in the plasma membrane 
C)  Antiport transport protein in the nuclear membrane 
D)  Ion channel in the cell wall 
E)  Auxin binding protein in the plasma membrane 
A)  ATPase proton pump in the tonoplast 
B)  ATPase proton pump in the plasma membrane 
C)  Antiport transport protein in the nuclear membrane 
D)  Ion channel in the cell wall 
E)  Auxin binding protein in the plasma membrane

Exam 19: Plant Hormones and Growth Responses

Phototropism is a phenomenon whereby

The plant hormone auxin has many effects on plant growth EXCEPT

At the end of a long day what is the relative level of CO and how does this in turn affect the expression of the FT gene and thus flowering?

In young seedlings, the development of which organs is affected when expression of the auxin binding protein (ABP) is inhibited?

In which one of the following processes in plants is abscisic acid NOT involved?

During the vegetative phase of 'short day' plants, the interruption of the dark period with a ten-minute period of light will

In addition to stem elongation, gibberellins are thought to be involved in

The most important activity of abscisic acid is

IAA is thought to be involved in apical dominance through

The critical factor inducing flowering in plants is

What is the effective temperature range for plant to respond to vernalisation, and for how long will a plant typically need to be exposed to this temperature range?

Amyloplasts contain

Which of the following statements about ethylene is true?

Growth inhibitors in plants

IAA produces a phototropic response in plants

Short-day plants flower in response to a

What phenotype is associated with PIN1 mutants?

Ethylene affects plant growth by reacting with a receptor which is located in the

Plant growth responses are regulated by

It is hypothesised that auxin stimulates cell elongation, and therefore plant growth, by triggering the release of H+ inside cells and therefore acidifying the intracellular environment. What protein would need to be activated to achieve this, and where would it be located?

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It is hypothesised that auxin stimulates cell elongation, and therefore plant growth, by triggering the release of H⁺ inside cells and therefore acidifying the intracellular environment. What protein would need to be activated to achieve this, and where would it be located?