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Questions and Answers
What is the primary function of auxin in plant cells?
What is the primary function of auxin in plant cells?
Cell elongation/growth patterning
What are the synthetic auxins commonly used as herbicides?
What are the synthetic auxins commonly used as herbicides?
α-Naphthaleneacetic acid (αNAA) and 2,4-Dichlorophenoxyacetic acid (2,4-D)
How is auxin degraded in plant cells?
How is auxin degraded in plant cells?
Decarboxylation or oxidation
What is the primary role of abscisic acid in plants?
What is the primary role of abscisic acid in plants?
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What hormone is involved in the acid growth process, leading to cell expansion and elongation?
What hormone is involved in the acid growth process, leading to cell expansion and elongation?
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Name at least three characteristics of plant growth regulators (PGRs).
Name at least three characteristics of plant growth regulators (PGRs).
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How do plant hormones differ from animal hormones?
How do plant hormones differ from animal hormones?
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Name two plant hormones that mainly mediate stress responses.
Name two plant hormones that mainly mediate stress responses.
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What is the capacity of plant growth regulators (PGRs) in terms of stimulating and inhibiting physiological processes?
What is the capacity of plant growth regulators (PGRs) in terms of stimulating and inhibiting physiological processes?
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How do plant hormones differ in their effects on plant physiology?
How do plant hormones differ in their effects on plant physiology?
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Plant growth regulators are exclusively internal signals that regulate plant growth.
Plant growth regulators are exclusively internal signals that regulate plant growth.
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Plant hormones are mainly produced in large quantities (greater than 10 µM) by a plant.
Plant hormones are mainly produced in large quantities (greater than 10 µM) by a plant.
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Auxin and Cytokinin mainly mediate stress responses in plants.
Auxin and Cytokinin mainly mediate stress responses in plants.
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The effect of plant hormones on plant physiology is solely dependent on the tissue sensitivity to the PGR.
The effect of plant hormones on plant physiology is solely dependent on the tissue sensitivity to the PGR.
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Plant hormones are primarily made in tissues specialized for hormone production.
Plant hormones are primarily made in tissues specialized for hormone production.
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Auxins are only produced by the pituitary gland.
Auxins are only produced by the pituitary gland.
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Cytokinins primarily inhibit cell division and differentiation.
Cytokinins primarily inhibit cell division and differentiation.
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Gibberellins are primarily responsible for bud and seed dormancy as well as stress responses.
Gibberellins are primarily responsible for bud and seed dormancy as well as stress responses.
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Abscisic acid promotes shoot elongation and apical dominance.
Abscisic acid promotes shoot elongation and apical dominance.
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Auxin promotes cell expansion through a process of alkalization of the cell wall.
Auxin promotes cell expansion through a process of alkalization of the cell wall.
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Study Notes
Auxin Function
- Auxin's primary function is to promote cell elongation and expansion.
Synthetic Auxin Herbicides
- 2,4-D (2,4-dichlorophenoxyacetic acid)
- 2,4,5-T (2,4,5-trichlorophenoxyacetic acid)
Auxin Degradation
- Auxin is degraded in plant cells through a process called oxidation.
Abscisic Acid Role
- Abscisic acid (ABA) is primarily responsible for regulating stress responses, such as drought, salinity, and cold stress.
- Plays a critical role in seed dormancy and bud dormancy.
Acid Growth Process
- Auxin is the primary hormone involved in the acid growth process.
- This involves acidification of the cell wall, leading to cell expansion and elongation.
Plant Growth Regulator Characteristics
- Produced in small quantities, but have a large effect
- Act as chemical messengers, regulating growth and development
- Can be transported throughout the plant, affecting distant tissues
Plant vs. Animal Hormones
- Plant hormones are produced in various tissues and can act locally or be transported long distances.
- Animal hormones are generally produced in specialized glands and transported through the circulatory system.
Stress Response Hormones
- Abscisic acid (ABA)
- Ethylene
PGR Stimulation and Inhibition
- Plant growth regulators can both stimulate and inhibit physiological processes, depending on the specific hormone, concentration, and tissue.
Plant Hormone Effects On Plant Physiology
- Plant hormone effects on plant physiology are complex and vary depending on the hormone, concentration, and tissue type.
- Hormones can interact with each other, creating synergistic or antagonistic effects.
Plant Growth Regulator Production
- Plant growth regulators are typically produced in small quantities and can be found in all plant tissues.
Auxin Production
- Auxin is produced in various tissues, including the shoot apical meristem, young leaves, and root tips.
Cytokinin and Stress Response
- Cytokinins promote cell division, and while they play roles in various processes, their primary role is not mediating stress responses.
Plant Hormone Effects and Tissue Influence
- The sensitivity of a tissue to a specific PGR influences the response.
Hormone Specialization
- While hormones can be produced in various tissues, some tissues are more specialized for hormone production.
Auxin Production Location
- Auxins are not just produced in the pituitary gland; they are produced throughout the plant in various tissues.
Cytokinin Function
- Cytokinins primarily promote cell division and differentiation.
Gibberellin Functions
- Gibberellins promote stem elongation, seed germination, and break bud dormancy.
Abscisic Acid Functions
- Abscisic acid inhibits shoot elongation and promotes apical dominance.
Auxin and Cell Expansion
- Auxin promotes cell expansion through a process of acidification of the cell wall, not alkalization.
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Description
Test your knowledge about plant growth regulators (PGR) and plant hormones which are internal and external signals that regulate plant growth. Explore the communication within and between cells and the local signal transduction processes. Learn about the physiological processes stimulated or inhibited by these regulators.
