Podcast
Questions and Answers
A botanist observes that a plant's stomata remain closed, even under conditions where they would typically open. Which hormone is most likely responsible for this?
A botanist observes that a plant's stomata remain closed, even under conditions where they would typically open. Which hormone is most likely responsible for this?
- Abscisic acid (correct)
- Auxin
- Cytokinin
- Gibberellin
A farmer notices delayed fruit ripening in their orchard. Which hormone treatment would most directly address this issue?
A farmer notices delayed fruit ripening in their orchard. Which hormone treatment would most directly address this issue?
- Ethylene (correct)
- Cytokinin
- Gibberellin
- Auxin
A researcher is studying the effects of plant hormones on root growth. They observe that a particular hormone inhibits root elongation but promotes shoot elongation. Which hormone are they most likely studying?
A researcher is studying the effects of plant hormones on root growth. They observe that a particular hormone inhibits root elongation but promotes shoot elongation. Which hormone are they most likely studying?
- Gibberellin
- Auxin (correct)
- Abscisic acid
- Cytokinin
A plant breeder wants to develop a variety of grapes that are seedless. Application of which of the following hormones would best help achieve this goal?
A plant breeder wants to develop a variety of grapes that are seedless. Application of which of the following hormones would best help achieve this goal?
A horticulturist wants to stimulate cell division in plant tissue cultures. Which of the following plant hormones would be most effective for this purpose?
A horticulturist wants to stimulate cell division in plant tissue cultures. Which of the following plant hormones would be most effective for this purpose?
A scientist discovers a new plant mutant that is unable to enter dormancy even under harsh environmental conditions. Which hormone is most likely deficient in this mutant?
A scientist discovers a new plant mutant that is unable to enter dormancy even under harsh environmental conditions. Which hormone is most likely deficient in this mutant?
Which of the following hormones is primarily responsible for the ripening of fruits and is often associated with the use of calcium carbide to accelerate this process?
Which of the following hormones is primarily responsible for the ripening of fruits and is often associated with the use of calcium carbide to accelerate this process?
A researcher is investigating the effect of plant hormones on the ageing process in leaves. Which hormone is most likely to delay senescence?
A researcher is investigating the effect of plant hormones on the ageing process in leaves. Which hormone is most likely to delay senescence?
Study Notes
- Dormancy promotion, dormancy breakage, stomata control, leaf abscission, fruit development, fruit ripening, and plant senescence are under the control of various plant hormones.
- There are four primary categories of plant hormones: auxins, gibberellins, cytokinins, abscisic acid, and ethylene gas.
- Auxins, gibberellins, and cytokinins stimulate plant growth, whereas abscisic acid inhibits it.
Auxins
- Auxins induce cell proliferation and differentiation in plants.
- Auxins stimulate fruit development.
- Auxins mediate phototropic and geotropic responses.
- Auxins are created at the stem and root tips.
- Auxins are transported away from light and toward gravity.
- Auxins stimulate stem development while slowing root growth.
- Synthetic auxins, such as indole-3-acetic acid and 2,4-D, are utilized in agriculture and horticulture.
Gibberellins
- Gibberellins stimulate cell proliferation and differentiation in the presence of auxins.
- Gibberellins aid in stem elongation, dormancy breaking in seeds and buds, and germination promotion.
- Gibberellins stimulate fruit development.
- Gibberellic acid (GA3) is sprayed on grape vines to cause parthenocarpy (seedless grape development).
Cytokinins
- Cytokinins stimulate cell division in plants.
- Cytokinins aid in breaking seed and bud dormancy.
- Cytokinins inhibit leaf senescence.
- Cytokinins promote stomata opening and fruit development.
Abscisic Acid
- Abscisic acid is a growth inhibitor.
- Abscisic acid stimulates seed and bud dormancy.
- Abscisic acid aids in stomata closure.
- ABA promotes leaf wilting and abscission.
- Abscisic acid causes flower and fruit detachment from plants.
Ethylene Gas
- Ethylene gas promotes fruit ripening.
- Ripe fruits release ethylene gas, which accelerates ripening in surrounding unripe fruits.
- Calcium carbide generates acetylene gas when combined with water.
- Acetylene gas, such as ethylene gas, aids in fruit ripening.
- Fruit sellers utilize calcium carbide to accelerate fruit ripening.
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