Podcast
Questions and Answers
A plant is placed on its side. Which hormone primarily facilitates the roots growing downwards?
A plant is placed on its side. Which hormone primarily facilitates the roots growing downwards?
- Ethylene
- Gibberellin
- Auxin (correct)
- Cytokinin
Which hormone is most likely responsible for a farmer's apples ripening too quickly?
Which hormone is most likely responsible for a farmer's apples ripening too quickly?
- Abscisic Acid
- Ethylene (correct)
- Cytokinin
- Gibberellin
A plant's growth is stunted, and the leaves are starting to yellow prematurely. Which hormone deficiency could be the cause?
A plant's growth is stunted, and the leaves are starting to yellow prematurely. Which hormone deficiency could be the cause?
- Auxin
- Cytokinin (correct)
- Abscisic Acid
- Ethylene
What is the term for the type of plant growth that grows diagonally to the stimulus of gravity, neither directly with nor against it?
What is the term for the type of plant growth that grows diagonally to the stimulus of gravity, neither directly with nor against it?
A nursery wants to prevent seeds from germinating too early. Which hormone application would best serve this purpose?
A nursery wants to prevent seeds from germinating too early. Which hormone application would best serve this purpose?
A scientist observes a plant bending towards a light source. Which of the following explains this?
A scientist observes a plant bending towards a light source. Which of the following explains this?
A plant exhibits strong apical dominance. Which hormone is likely present in high concentrations in the apical bud?
A plant exhibits strong apical dominance. Which hormone is likely present in high concentrations in the apical bud?
A short-day plant is exposed to a flash of light during its critical dark period. What is the likely outcome?
A short-day plant is exposed to a flash of light during its critical dark period. What is the likely outcome?
What role does abscisic acid play in the formation of an abscission layer?
What role does abscisic acid play in the formation of an abscission layer?
A plant species normally requires a period of cold temperatures to induce flowering. What is this process known as?
A plant species normally requires a period of cold temperatures to induce flowering. What is this process known as?
How does a plant growing in complete darkness compensate for their lack of light?
How does a plant growing in complete darkness compensate for their lack of light?
A botanist observes that a certain plant species flowers only when day lengths exceed 14 hours. How would you classify this plant?
A botanist observes that a certain plant species flowers only when day lengths exceed 14 hours. How would you classify this plant?
How does the concentration of auxin typically differ between the illuminated and shaded sides of a plant stem, and what effect does this have?
How does the concentration of auxin typically differ between the illuminated and shaded sides of a plant stem, and what effect does this have?
A plant suddenly sends up a very tall stem and prepares to flower. What is the general term for this process, often triggered by seasonal changes?
A plant suddenly sends up a very tall stem and prepares to flower. What is the general term for this process, often triggered by seasonal changes?
Which of the following plant responses is classified as a nastic movement, rather than a tropism?
Which of the following plant responses is classified as a nastic movement, rather than a tropism?
How does the interplay between auxin and cytokinin affect apical dominance?
How does the interplay between auxin and cytokinin affect apical dominance?
A farmer notices that their recently planted seeds are failing to germinate even though the conditions seem right. Which hormone might be present in excessive amounts?
A farmer notices that their recently planted seeds are failing to germinate even though the conditions seem right. Which hormone might be present in excessive amounts?
In what way are plant hormone effects modulated by environmental factors such as temperature and day length?
In what way are plant hormone effects modulated by environmental factors such as temperature and day length?
If a plant is genetically modified to be insensitive to ethylene, which of the following processes would be most affected?
If a plant is genetically modified to be insensitive to ethylene, which of the following processes would be most affected?
A plant maintains its leaves in the winter. Which hormone will be present in low levels?
A plant maintains its leaves in the winter. Which hormone will be present in low levels?
Flashcards
Tropism
Tropism
Directional movement responses to a directional stimulus.
Hormone (in plants)
Hormone (in plants)
Signal molecules influencing plant growth and development.
Geotropism
Geotropism
Plant growth in response to gravity.
Phototropism
Phototropism
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Diageotropism
Diageotropism
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Plagiotropism
Plagiotropism
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Auxin
Auxin
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Gibberellin
Gibberellin
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Cytokinin
Cytokinin
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Ethylene
Ethylene
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Abscisic Acid
Abscisic Acid
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Etiolation
Etiolation
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Apical Dominance
Apical Dominance
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Vernalization
Vernalization
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Photoperiod
Photoperiod
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Bolting
Bolting
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Abscission Layer
Abscission Layer
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Long Day Plant
Long Day Plant
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Short Day Plant
Short Day Plant
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Nastic Movements
Nastic Movements
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Study Notes
- Tropism is the directional movement of plants in response to a directional stimulus.
- Hormones act as signal molecules produced in plants.
Types of Tropism
- Geotropism is the growth of a plant in response to gravity.
- Phototropism is plant growth towards or away from light.
- Diageotropism is the growth of a plant across the stimulus of gravity, resulting in diagonal growth.
- Plagiotropism is the growth pattern seen in samples like branches, as opposed to the main trunk of a tree.
Plant Hormones
- Auxin promotes stem elongation and growth, stimulates cell elongation, and controls phototropism and geotropism.
- Gibberellin promotes seed and bud germination, stem elongation, and leaf growth, stimulates flowering and fruiting, and affects root growth.
- Cytokinin affects root growth and differentiation, cell growth and mitosis, and delays senescence.
- Ethylene promotes fruit ripening and growth and opposes some auxin effects.
- Abscisic Acid inhibits growth, triggers dormancy, and delays germination.
Other Terms
- Etiolation describes the growth of plants in the absence of light.
- Apical dominance is growth mainly at the apical bud, driven by auxin accumulation.
- Vernalization is the process where low temperatures promote flowering.
- Photoperiod is the term for day length.
- Bolting is a change in foliage where plants shoot up stems and flowers for reproduction, typically a seasonal response.
- The Abscission layer is tissue that forms at the petiole of a leaf, closing it off from the rest of the plant and triggered by abscisic acid.
- Long day plants bloom when the photoperiod is longer than 12 hours.
- Short day plants bloom when the photoperiod is shorter than 12 hours.
- Nastic movements are plant movements controlled by hormones but not by tropisms.
Additional Points
- Many hormones and tropisms can be active at once.
- Hormones can oppose each other.
- Hormones are affected by the environment, including temperature and day length.
- Plants bloom according to the period of uninterrupted darkness they receive.
- Regardless of the orientation of a planted seed, shoots will always grow upwards and roots downwards due to geotropism.
- Sunlight breaks down auxin, creating a concentration of auxin on the shadier side of a plant stem.
- This causes the cells there to elongate and grow, bending the stem in response to the sunlight, which is known as phototropism
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