Heavy Metal Signaling in Plants
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Questions and Answers

What role does copper (Cu) play in plants?

  • It exclusively functions as a toxic compound.
  • It is crucial for enzymes catalytic activity. (correct)
  • It does not affect the signaling processes in plants.
  • It acts as a primary nutrient without any further functions.

    • How does excess copper (Cu) affect plants at the cellular level?

  • It leads to the reduction of antioxidant levels only.
  • It triggers a response that increases expression of phyto-chelatins and antioxidants. (correct)
  • It prevents transcription factors from binding to DNA.
  • It primarily causes cell death without recovery mechanisms.

    • What is a key characteristic of cadmium (Cd) in its transport within plants?

  • It is taken up specifically through dedicated uptake channels.
  • It requires a active transport mechanism unique to cadmium.
  • It enters cells via general metal transporters or possibly Ca channels. (correct)
  • It interacts only with copper transporters.

    • What kind of oxidative stress does cadmium (Cd) cause in plants?

    <p>It causes oxidative stress by stimulating H₂O₂ production.</p> Signup and view all the answers

    In the context of heavy metal signaling, what is the main function of phyto-chelatins?

    <p>They help in detoxifying excess heavy metals.</p> Signup and view all the answers

    What is the primary hormone that accumulates due to excess heavy metals in plants?

    <p>Abscisic Acid (ABA)</p> Signup and view all the answers

    How do cytokinins interact with cadmium (Cd) in plants?

    <p>They act as antagonists to cadmium effects.</p> Signup and view all the answers

    Which of the following is NOT considered a source of heavy metal pollution?

    <p>Photosynthesis</p> Signup and view all the answers

    What is a limitation of the biological definition of heavy metals?

    <p>It encompasses many naturally occurring elements.</p> Signup and view all the answers

    What does cadmium (Cd) activate in plants that is also seen with other abiotic stresses?

    <p>Stress signaling pathways</p> Signup and view all the answers

    Study Notes

    Heavy Metal Signaling in Plants

    • Heavy metals are essential micronutrients or toxic compounds in plants
    • Plants perceive heavy metals, triggering adaptation or injury responses
    • Copper (Cu) and cadmium (Cd) are examples of heavy metals with contrasting properties
    • Cu is an essential ligand for many plant enzymes
    • Cu uptake and transport are regulated by specific transporters and chaperones
    • Cu acts as a signaling molecule for ethylene reception
    • Excess Cu binds to transcription factors, activating stress responses (increased metal ion expression, phyto-chelatins, and antioxidants) to restore cellular ion and redox balance
    • In contrast to Cu, Cd uptake does not have specific systems
    • Cd enters cells via general metal transporters and potentially calcium channels
    • Cd is toxic due to high reactivity with sulfhydryl groups, causing oxidative stress (antioxidant depletion and H₂O₂ stimulation)
    • Cd triggers stress signaling pathways similar to those activated by Cu
    • Heavy metals cross-talk with other abiotic stress signaling pathways (drought, oxidative stress)
    • Excess heavy metals affect root functions and cause abscisic acid (ABA) accumulation
    • ABA and Cd signaling may interact at the organismic level, influencing plant water status
    • Phytohormones such as cytokinins act as antagonists of Cd, indicating that plant internal hormonal status may critically affect heavy metal tolerance
    • Heavy metals are defined as metals with a density higher than 5 g cm⁻³
    • Only a limited number of heavy metals are available to living cells under physiological conditions due to their limited solubility.

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    Description

    Explore the role of heavy metals in plant signaling and stress responses in this quiz. Learn how copper and cadmium affect plant health and adaptation, and understand the mechanisms behind metal uptake and transport. Test your knowledge on the contrasting properties of these essential micronutrients and toxic compounds.

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