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Questions and Answers
[Blank] are the main hormones responsible for cell elongation in phototropism and gravitropism.
[Blank] are the main hormones responsible for cell elongation in phototropism and gravitropism.
Auxins
The term auxin is derived from the Greek word auxein, which means 'to ______'.
The term auxin is derived from the Greek word auxein, which means 'to ______'.
grow
[Blank] is the growth and development of plants in response to light, enabling them to optimize their use of light and space.
[Blank] is the growth and development of plants in response to light, enabling them to optimize their use of light and space.
Photomorphogenesis
[Blank] is a directional response that allows plants to grow towards, or even away from, light.
[Blank] is a directional response that allows plants to grow towards, or even away from, light.
Phototropism is specifically a response to ______ wavelengths of light.
Phototropism is specifically a response to ______ wavelengths of light.
Positive phototropism is growth ______ a light source.
Positive phototropism is growth ______ a light source.
Negative phototropism, also called skototropism, is growth ______ from light.
Negative phototropism, also called skototropism, is growth ______ from light.
[Blank] are protein-based receptors responsible for mediating the phototropic response.
[Blank] are protein-based receptors responsible for mediating the phototropic response.
[Blank] work together with phototropins to mediate the phototropic response.
[Blank] work together with phototropins to mediate the phototropic response.
[Blank] ensures that roots grow into the soil, and shoots grow toward sunlight.
[Blank] ensures that roots grow into the soil, and shoots grow toward sunlight.
Growth of the shoot apical tip upward is called ______ gravitropism.
Growth of the shoot apical tip upward is called ______ gravitropism.
Growth of the roots downward is called ______ gravitropism.
Growth of the roots downward is called ______ gravitropism.
[Blank], also known as statoliths, are specialized plastids that contain starch granules and settle downward in response to gravity.
[Blank], also known as statoliths, are specialized plastids that contain starch granules and settle downward in response to gravity.
[Blank] is the movement of a plant subjected to constant directional pressure.
[Blank] is the movement of a plant subjected to constant directional pressure.
The Greek word thigma, which forms part of thigmotropism, means ______.
The Greek word thigma, which forms part of thigmotropism, means ______.
[Blank] is a slow developmental change in the shape of a plant subjected to continuous mechanical stress.
[Blank] is a slow developmental change in the shape of a plant subjected to continuous mechanical stress.
When trees bend in the ______, growth is usually stunted, and the trunk thickens to resist the force.
When trees bend in the ______, growth is usually stunted, and the trunk thickens to resist the force.
Researchers hypothesize that ______ strain induces growth and differentiation to strengthen the tissues.
Researchers hypothesize that ______ strain induces growth and differentiation to strengthen the tissues.
[Blank] and jasmonate are likely involved in thigmomorphogenesis.
[Blank] and jasmonate are likely involved in thigmomorphogenesis.
[Blank] are one example of thigmotropism, showing a quick coiling response with light touch.
[Blank] are one example of thigmotropism, showing a quick coiling response with light touch.
The meristematic region of tendrils is very touch sensitive; light touch will evoke a quick ______ response.
The meristematic region of tendrils is very touch sensitive; light touch will evoke a quick ______ response.
A ______ response is a touch response independent of the direction of stimulus.
A ______ response is a touch response independent of the direction of stimulus.
In the Venus flytrap, two modified leaves are joined at a hinge and lined with thin fork-like ______ along the outer edges.
In the Venus flytrap, two modified leaves are joined at a hinge and lined with thin fork-like ______ along the outer edges.
In the Venus flytrap, tiny ______ are located inside the trap, triggering its closure when touched.
In the Venus flytrap, tiny ______ are located inside the trap, triggering its closure when touched.
The cells at the base of the leaflets lose ______ , which keeps them upright before being touched.
The cells at the base of the leaflets lose ______ , which keeps them upright before being touched.
Plants develop ______ as one of their first defense responses.
Plants develop ______ as one of their first defense responses.
Plants discourage animals by causing physical damage and inducing ______ and allergic reactions.
Plants discourage animals by causing physical damage and inducing ______ and allergic reactions.
If the first line of defense is breached, the plant must resort to a different set of defense mechanisms, such as ______ and enzymes.
If the first line of defense is breached, the plant must resort to a different set of defense mechanisms, such as ______ and enzymes.
The plant may activate ______ of injured tissue if it is damaged beyond repair.
The plant may activate ______ of injured tissue if it is damaged beyond repair.
Some defense reactions occur within minutes; others over several ______.
Some defense reactions occur within minutes; others over several ______.
Flashcards
What are auxins?
What are auxins?
Auxins are hormones that cause cell elongation in phototropism and gravitropism.
What is photomorphogenesis?
What is photomorphogenesis?
Growth and development of plants in response to light, optimizing light and space use.
What is phototropism?
What is phototropism?
A directional response where plants grow towards or away from light.
What is positive phototropism?
What is positive phototropism?
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What is negative phototropism?
What is negative phototropism?
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What are phototropins?
What are phototropins?
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What is gravitropism?
What is gravitropism?
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What is negative gravitropism?
What is negative gravitropism?
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What is positive gravitropism?
What is positive gravitropism?
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What are amyloplasts?
What are amyloplasts?
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What is thigmotropism?
What is thigmotropism?
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What is thigmomorphogenesis?
What is thigmomorphogenesis?
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What is thigmonastic response?
What is thigmonastic response?
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How does venus flytrap work?
How does venus flytrap work?
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Why leaves of makahiya plant close when touched?
Why leaves of makahiya plant close when touched?
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Study Notes
- Plants have sensory systems and responses allowing them to respond to their environment.
Growth Responses
- Auxins are the primary hormones responsible for cell elongation in phototropism and gravitropism
- Auxin is derived from the Greek word "auxein," which translates to "to grow"
Plant Responses to Light
- Photomorphogenesis is the growth and development of plants in response to light
- This enables plants to optimize their light and space utilization
- Phototropism is a directional response enabling plants to grow towards or away from light, specifically in response to blue wavelengths
Positive & Negative Phototropism
- Positive phototropism involves growth towards a light source
- Negative phototropism, also known as skototropism, involves growth away from light
- Phototropins are protein-based receptors that mediate the phototropic response
- Cryptochromes may work with phototropins to mediate the phototropic response
Plant Responses to Gravity
- Gravitropism ensures root growth into the soil and shoot growth toward sunlight
- Negative gravitropism refers to the upward growth of the shoot apical tip
- Positive gravitropism refers to the downward growth of roots
- Amyloplasts, also known as statoliths, are specialized plastids containing starch granules that settle downward in response to gravity
Plant Responses to Wind and Touch
- Thigmotropism is the movement of a plant subjected to constant directional pressure
- The word comes from the Greek words "thigma" meaning "touch," and "tropism" implying "direction"
Thigmomorphogenesis
- Thigmomorphogenesis is a gradual change in a plant's shape due to continuous mechanical stress
- For example, when trees bend in the wind, growth may be stunted, and the trunk thickens, leading to the production of strengthening tissue/xylem to withstand the wind's force
- Mechanical strain induces growth and differentiation to strengthen tissues
- Ethylene and jasmonate are likely involved in thigmomorphogenesis
- Tendrils are examples of thigmotropism
- The meristematic region of tendrils is very touch-sensitive, triggering a quick coiling response even with light touch
Thigmonastic Response
- Thigmonastic response is a touch response irrespective of the direction of the stimulus
Thigmonastic Response Example
- In the Venus flytrap, two modified leaves are joined at a hinge, lined with thin fork-like tines
- Tiny hairs are located inside the trap
- When an insect brushes against two or more of these hairs successively, the leaves close rapidly, trapping the prey
Makahiya Plant
- The leaves of the makahiya plant close upon touch because the cells at the base of the leaflets lose turgor pressure, which keeps them upright before being touched
Defense Responses against Herbivores and Pathogens
- Plants develop barks to protect themselves
- Plants discourage animals by causing physical damage like rashes and allergic reactions
- If the initial defense fails, plants use toxins and enzymes, or activate abscission of injured tissue if beyond repair
- Some defense reactions occur rapidly, while others take hours
- Infected cells may die to prevent infection spread
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