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Questions and Answers
What triggers the closing of stomata in plant leaves?
Which part of the plant is primarily responsible for sensing environmental dryness?
What happens to stomata when an increase in leaf-air vapor pressure difference is detected?
What can be inferred about the relationship between root water and stomatal behavior?
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What is one function of the systems in plant roots and leaves?
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Which gene is mentioned as being drought-inducible?
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What condition do the genes mentioned express under without requiring ABA?
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What regulatory system is described as being majorly ABA-independent?
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Which of these does NOT require ABA for gene expression under the given stress conditions?
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What is the main focus of the pathway mentioned in the content?
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What is the typical depth range of a mesquite's roots?
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What characteristic is noted about the roots of xerophytes like mesquites?
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Which of the following statements about mesquite roots is accurate?
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Why are xerophytes like mesquites adapted to exploit deeper soil?
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What is a common feature of the root systems of xerophytes?
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Which group of protein factors is primarily involved in regulating gene expression during stress response?
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Which of the following is NOT a protein kinase mentioned in the content?
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How many ABA-dependent pathways are hypothesized to activate stress-inducible genes under dehydration conditions?
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Which of the following phospholipids is suggested to be involved in stress signaling processes?
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What role do transcription factors play under stress conditions?
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What do the drought-inducible genes that do not respond to cold or ABA treatment imply?
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Which pathways are the drought-inducible genes NOT responsive to?
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Which statement is accurate regarding the dehydration stress response?
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Pathway III in the dehydration stress response is characterized by genes that...
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Which of the following is NOT indicated by the drought-inducible genes?
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Study Notes
Plant Responses to Drought
- Plants have specialized systems in their roots and leaves that sense environmental dryness.
- Leaf stomata close immediately when sensing increased leaf-air vapor pressure difference, even if the roots have sufficient water.
- There are at least four independent signal transduction pathways that function in the activation of stress-inducible genes under dehydration conditions.
- Two are ABA-dependent (Pathways I and II)
- Two are ABA-independent (Pathways III and IV).
- A fourth pathway, ABA independent, is suggested by drought-inducible genes that don't respond to cold or ABA treatment.
- This pathway is known as Pathway III.
ABA-Independent Regulatory System of Gene Expression during Drought and Cold Stress
- Genes involved in Pathway IV do not require the hormone ABA for their expression under cold or drought conditions.
- Some examples of genes in Pathway IV include rd29A/lti78/cor78.
- These genes are drought-inducible.
Proteins Involved in Stress Response
- Protein kinases like MAP kinases, Calcium dependent protein kinases (CDPK), SNF1 related protein kinase, and Ribosomal S6 kinase are involved in stress response.
- These kinases modify functional and regulatory proteins, playing a role in stress signal transduction pathways.
- Transcription factors are key in regulating functional genes under stress conditions.
- Phospholipids like inositol-1,4,5-triphosphate, diacylglycerol and phospahtidic acid are involved in stress signaling processes in plants.
Root Adaptations
- Xerophytes, plants adapted to arid conditions, have root systems that exploit soil at greater depths than succulents.
- Roots can extend to extreme depths, for example, mesquite trees.
- The majority of a mesquite's roots are within three feet (0.9 m) of the surface.
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Description
Explore the specialized systems plants possess for sensing drought conditions and their corresponding adaptive responses. This quiz covers various signal transduction pathways involved in regulating gene expression under dehydration stress and highlights the roles of ABA-dependent and ABA-independent pathways.
