BZ440 Plant Physiology Final Exam Preparation Guide Questions and Answers Already Passed
Can scientists predict with certainty where an inserted gene will go on a plant chromosome in
agrobacterium transformation? - Answers Genes are inserted on the proper chromosome, but
there is no control on where they go on the chromosome- shot in the dark
What factors control plant development? - Answers Internal factors (genetic makeup of the cell),
external environment, and nutritional conditions.
What are the components of the signal cascade pathway in plants? - Answers Signal, receptors,
secondary messengers, effectors, and the response.
Where can receptors be localized in plant cells? - Answers Receptors can be membrane-
localized (plasma membrane or organellar membranes) or cytoplasmic.
What are the most common secondary messengers in plants? - Answers Ca2+, changing the pH,
and reactive oxygen species (ROS).
What roles do effectors play in the signal cascade pathway? - Answers Effectors can be
transcription factors that manipulate gene expression or protein kinases/phosphatases that
phosphorylate/dephosphorylate proteins, activating or deactivating the signal cascade.
What are some examples of responses resulting from signal transduction in plants? - Answers
Phototropism, seed germination, seed dormancy, flowering, and changing tissue identity from
vegetative to reproductive.
What are hormones in the context of plant biology? - Answers Hormones are the most common
signal molecules affecting plant growth, development, and all aspects of plant life.
How does auxin-induced cell expansion occur? - Answers It is an example of a signal cascade
pathway that involves auxin's role in cell elongation.
What are the three levels of hormone regulation in plants? - Answers Biosynthesis, degradation,
and perception or sensitivity.
How do hormones differ from enzymes in plants? - Answers Hormones are signaling molecules
consumed during reactions and transported over long distances, while enzymes are catalysts
that function within the same cell and are not consumed.
What are the three concentrations at which hormones function? - Answers Sub-optimum,
optimum, and supra-optimum concentrations.
How does the herbicide 2,4-D affect different plant types? - Answers It kills broad-leaved weeds
(dicots) but not grass (monocots) because dicots are more sensitive to auxin.
What is auxin and where is it synthesized? - Answers Auxin is the first discovered plant hormone,
synthesized in the shoot apex, root apex, and young leaves.
, How is auxin transported in plants? - Answers Auxin is transported basipetally (polar transport,
away from the source).
What responses are regulated by auxins? - Answers Phototropism, gravitropism, thigmotropism,
and apical dominance.
What happens to seedlings under unilateral illumination? - Answers They grow towards the light
source due to lateral movement of auxin and unequal growth.
What is the role of the photoreceptor 'phototropin' in plants? - Answers Phototropin is the blue
light photoreceptor that induces lateral movement of auxin, causing bending towards the light.
How does auxin affect root and shoot growth in gravitropism? - Answers Auxin accumulation on
the lower side inhibits cell elongation in the root while inducing cell expansion in the shoot.
What is the mechanism of gravity sensing in roots? - Answers Gravity sensing occurs in the root
apex through starch granules (statoliths) that are denser than the cytoplasm.
What is apical dominance and how is it affected by auxin? - Answers Apical dominance is the
phenomenon where the main shoot grows more strongly than lateral shoots, regulated by auxin
transport.
What happens if a plant has a nonfunctional auxin transporter gene? - Answers The plant does
not show apical dominance, phototropic, or gravitropic responses.
What effect does auxin have on lateral bud growth? - Answers Auxin inhibits the growth of
lateral buds by inhibiting cytokinin production.
What is the role of auxin in apical dominance? - Answers Auxin produced in the apical bud
suppresses lateral bud growth.
How does auxin affect leaf and fruit abscission? - Answers Auxin delays leaf and fruit
abscission by making the abscission zone less sensitive to ethylene.
What is the primary function of gibberellin (GA)? - Answers Gibberellin is involved in stem
elongation and seed germination.
What happens to a plant with low levels of gibberellin? - Answers A plant with low GA levels
becomes a dwarf and the seeds do not germinate.
What is the relationship between gibberellin and abscisic acid (ABA) in seed germination? -
Answers A high GA to ABA ratio promotes germination, while a high ABA to GA ratio maintains
seed dormancy.
What discovery led to the identification of cytokinins? - Answers Cytokinins were discovered
during the study of Agrobacterium infections that cause crown gall disease.
Can scientists predict with certainty where an inserted gene will go on a plant chromosome in
agrobacterium transformation? - Answers Genes are inserted on the proper chromosome, but
there is no control on where they go on the chromosome- shot in the dark
What factors control plant development? - Answers Internal factors (genetic makeup of the cell),
external environment, and nutritional conditions.
What are the components of the signal cascade pathway in plants? - Answers Signal, receptors,
secondary messengers, effectors, and the response.
Where can receptors be localized in plant cells? - Answers Receptors can be membrane-
localized (plasma membrane or organellar membranes) or cytoplasmic.
What are the most common secondary messengers in plants? - Answers Ca2+, changing the pH,
and reactive oxygen species (ROS).
What roles do effectors play in the signal cascade pathway? - Answers Effectors can be
transcription factors that manipulate gene expression or protein kinases/phosphatases that
phosphorylate/dephosphorylate proteins, activating or deactivating the signal cascade.
What are some examples of responses resulting from signal transduction in plants? - Answers
Phototropism, seed germination, seed dormancy, flowering, and changing tissue identity from
vegetative to reproductive.
What are hormones in the context of plant biology? - Answers Hormones are the most common
signal molecules affecting plant growth, development, and all aspects of plant life.
How does auxin-induced cell expansion occur? - Answers It is an example of a signal cascade
pathway that involves auxin's role in cell elongation.
What are the three levels of hormone regulation in plants? - Answers Biosynthesis, degradation,
and perception or sensitivity.
How do hormones differ from enzymes in plants? - Answers Hormones are signaling molecules
consumed during reactions and transported over long distances, while enzymes are catalysts
that function within the same cell and are not consumed.
What are the three concentrations at which hormones function? - Answers Sub-optimum,
optimum, and supra-optimum concentrations.
How does the herbicide 2,4-D affect different plant types? - Answers It kills broad-leaved weeds
(dicots) but not grass (monocots) because dicots are more sensitive to auxin.
What is auxin and where is it synthesized? - Answers Auxin is the first discovered plant hormone,
synthesized in the shoot apex, root apex, and young leaves.
, How is auxin transported in plants? - Answers Auxin is transported basipetally (polar transport,
away from the source).
What responses are regulated by auxins? - Answers Phototropism, gravitropism, thigmotropism,
and apical dominance.
What happens to seedlings under unilateral illumination? - Answers They grow towards the light
source due to lateral movement of auxin and unequal growth.
What is the role of the photoreceptor 'phototropin' in plants? - Answers Phototropin is the blue
light photoreceptor that induces lateral movement of auxin, causing bending towards the light.
How does auxin affect root and shoot growth in gravitropism? - Answers Auxin accumulation on
the lower side inhibits cell elongation in the root while inducing cell expansion in the shoot.
What is the mechanism of gravity sensing in roots? - Answers Gravity sensing occurs in the root
apex through starch granules (statoliths) that are denser than the cytoplasm.
What is apical dominance and how is it affected by auxin? - Answers Apical dominance is the
phenomenon where the main shoot grows more strongly than lateral shoots, regulated by auxin
transport.
What happens if a plant has a nonfunctional auxin transporter gene? - Answers The plant does
not show apical dominance, phototropic, or gravitropic responses.
What effect does auxin have on lateral bud growth? - Answers Auxin inhibits the growth of
lateral buds by inhibiting cytokinin production.
What is the role of auxin in apical dominance? - Answers Auxin produced in the apical bud
suppresses lateral bud growth.
How does auxin affect leaf and fruit abscission? - Answers Auxin delays leaf and fruit
abscission by making the abscission zone less sensitive to ethylene.
What is the primary function of gibberellin (GA)? - Answers Gibberellin is involved in stem
elongation and seed germination.
What happens to a plant with low levels of gibberellin? - Answers A plant with low GA levels
becomes a dwarf and the seeds do not germinate.
What is the relationship between gibberellin and abscisic acid (ABA) in seed germination? -
Answers A high GA to ABA ratio promotes germination, while a high ABA to GA ratio maintains
seed dormancy.
What discovery led to the identification of cytokinins? - Answers Cytokinins were discovered
during the study of Agrobacterium infections that cause crown gall disease.
