CH 8: Plant Defence Mechanisms
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Questions and Answers

What is one of the primary ways plants defend themselves?

  • Ability to move quickly
  • Physical barriers
  • Production of chemical compounds (correct)
  • Reproduction mechanisms

    • Which group of chemical compounds can be toxic when ingested by herbivores?

  • Lipids
  • Alcohols
  • Alkaloids (correct)
  • Carbohydrates

    • What is the role of tannins in plant defense mechanisms?

  • Enhance plant growth
  • Attract pollinators
  • Act as a source of energy for herbivores
  • Make proteins indigestible to animals (correct)

    • Why can't plants move to escape their predators or unfavorable conditions?

    <p>They are stationary organisms</p> Signup and view all the answers

    What are some functions served by the chemical compounds produced by plants?

    <p>Deterring attackers and surviving threats</p> Signup and view all the answers

    What are phytoalexins?

    <p>Antimicrobial compounds synthesized in response to pathogen invasion</p> Signup and view all the answers

    How do thorns protect plants?

    <p>By providing a sharp barrier against large herbivores</p> Signup and view all the answers

    What is the role of spines in cacti?

    <p>To reduce surface area of leaves and minimize water loss</p> Signup and view all the answers

    How do prickles differ from thorns?

    <p>Prickles are part of the plant's vascular system, while thorns are not</p> Signup and view all the answers

    Why is understanding plant defense mechanisms crucial for agriculture?

    <p>To reduce the need for chemical pesticides</p> Signup and view all the answers

    What is the purpose of alkaloids in plants' defense mechanisms?

    <p>Repel insects and herbivores</p> Signup and view all the answers

    How do tannins contribute to plant defense?

    <p>Bind to proteins, making them indigestible to animals</p> Signup and view all the answers

    Which environmental factors have plants developed defense mechanisms against?

    <p>Herbivores and pathogens</p> Signup and view all the answers

    What role do chemical compounds play in plant survival?

    <p>Provide defense against threats</p> Signup and view all the answers

    How do alkaloids deter herbivores?

    <p>Bind to proteins, making them indigestible</p> Signup and view all the answers

    What is the function of nicotine in tobacco plants?

    <p>Act as a natural pesticide</p> Signup and view all the answers

    In what way do tannins affect animal feeding behavior?

    <p>Reduce the nutritional value of plant tissue</p> Signup and view all the answers

    What is the significance of chemical defenses for plants' ecological niches?

    <p>Protect against threats and maintain ecological balance</p> Signup and view all the answers

    Why have plants evolved sophisticated defense mechanisms?

    <p>To survive and reproduce in fixed locations</p> Signup and view all the answers

    What impact do chemical compounds have on pathogens?

    <p>Act as antimicrobial agents against pathogens</p> Signup and view all the answers

    Which of the following is NOT a mechanism used by plants for defense against herbivores?

    <p>Increased water consumption to dilute toxins</p> Signup and view all the answers

    What purpose do prickles serve in plant defense?

    <p>Reducing the surface area of leaves to minimize water loss</p> Signup and view all the answers

    Which of the following is an example of a mechanical plant defense structure?

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

    What is the main function of phytoalexins in plant defense?

    <p>Inhibiting microbial growth</p> Signup and view all the answers

    How do thorns differ from spines as plant defense structures?

    <p>Thorns are part of the plant's vascular system, while spines are not.</p> Signup and view all the answers

    What role do sticky substances play in plant defense mechanisms?

    <p>Creating a physical barrier against herbivores</p> Signup and view all the answers

    Which of the following is true about volatile organic compounds produced by plants?

    <p>They attract predators or parasitoids of herbivores.</p> Signup and view all the answers

    What makes prickles different from thorns and spines in terms of structure?

    <p>Prickles are outgrowths from the epidermis or cortex, while thorns and spines are not connected.</p> Signup and view all the answers

    What is the role of volatile organic compounds produced by plants?

    <p>Repelling predators and attracting predators or parasitoids of herbivores</p> Signup and view all the answers

    What is the main purpose of thorns in plants?

    <p>To serve as a deterrent to herbivores and prevent them from reaching plant leaves</p> Signup and view all the answers

    How do prickles differ from thorns and spines?

    <p>Prickles are outgrowths from the epidermis or cortex and are not part of the vascular system</p> Signup and view all the answers

    In what way do phytoalexins contribute to plant defense?

    <p>They limit the spread of infections caused by pathogens</p> Signup and view all the answers

    What is one of the key functions of spines in cacti?

    <p>Minimizing water loss in arid environments by reducing leaf surface area</p> Signup and view all the answers

    Which of the following is NOT a common plant defense mechanism against herbivores?

    <p>Secretion of substances to attract herbivores</p> Signup and view all the answers

    How do sticky substances produced by some plants contribute to their defense?

    <p>They make it difficult for insects and other herbivores to consume plant tissues</p> Signup and view all the answers

    What is one of the functions served by mechanical defenses in plants?

    <p>Protecting plants from herbivores through physical barriers like thorns and spines</p> Signup and view all the answers

    What is the significance of understanding plant defense mechanisms for agriculture?

    <p>Aiding in more effective strategies for pest and disease management without using chemical pesticides</p> Signup and view all the answers

    What is one of the primary purposes served by phytoalexins in plants?

    <p>Limiting the spread of infections caused by pathogens invading the plant</p> Signup and view all the answers

    Why have plants developed sophisticated defense mechanisms?

    <p>To discourage animals from feeding on them.</p> Signup and view all the answers

    How do alkaloids contribute to plant defense against herbivores?

    <p>By repelling or being toxic to herbivores.</p> Signup and view all the answers

    What is the primary function of tannins in plant defense mechanisms?

    <p>Binding to proteins and making them indigestible to animals.</p> Signup and view all the answers

    Why are chemical defenses essential for plants' ecological niches?

    <p>To protect plants from damage caused by pathogens and herbivores.</p> Signup and view all the answers

    How do mechanical defenses differ from chemical defenses in plants?

    <p>Mechanical defenses are structural barriers, while chemical defenses involve toxic compounds.</p> Signup and view all the answers

    What is the main purpose of alkaloids in plant defense mechanisms?

    <p>To act as a natural pesticide against insects.</p> Signup and view all the answers

    How do tannins affect animal feeding behavior towards plants?

    <p>They reduce the nutritional value of plant tissue and discourage feeding.</p> Signup and view all the answers

    In what way do alkaloids differ from tannins in their defense mechanisms?

    <p>Alkaloids act as natural pesticides, while tannins bind to proteins making them indigestible.</p> Signup and view all the answers

    Which statement best describes the role of chemical defenses in plant survival?

    <p>To protect plants from pathogens and deter herbivores.</p> Signup and view all the answers

    What is one of the critical functions served by mechanical defenses in plants?

    <p>To deter herbivores and protect against environmental stresses.</p> Signup and view all the answers

    What is the primary reason why plants have evolved sophisticated defense mechanisms?

    <p>To ensure their survival, reproduction, and maintenance of ecological niches</p> Signup and view all the answers

    How do tannins contribute to plant defense?

    <p>By binding to proteins and reducing the nutritional value of plant tissue</p> Signup and view all the answers

    What is the role of phytoalexins in plant defense mechanisms?

    <p>To protect plants against environmental stresses</p> Signup and view all the answers

    How do alkaloids differ from tannins in their defense mechanisms?

    <p>Alkaloids deter herbivores through toxicity while tannins reduce nutritional value</p> Signup and view all the answers

    What impact do chemical defenses have on pathogens?

    <p>Chemical defenses are antimicrobial against bacteria, viruses, and fungi</p> Signup and view all the answers

    Why can't plants move to escape their predators or change locations?

    <p>Because they are stationary organisms</p> Signup and view all the answers

    What is the primary function of nicotine in tobacco plants for defense?

    <p>To deter herbivores due to its toxic effects</p> Signup and view all the answers

    What is one of the functions served by mechanical defenses in plants?

    <p>To provide structural support for the plant</p> Signup and view all the answers

    Which statement best describes the role of chemical defenses in plant survival?

    <p>Chemical defenses protect plants from environmental stresses and pathogens.</p> Signup and view all the answers

    What is the primary purpose of tannins in plant defense mechanisms?

    <p>To reduce the nutritional value of plant tissue for herbivores.</p> Signup and view all the answers

    Which plant defense mechanism involves the production of compounds that attract predators or parasitoids of herbivores?

    <p>Volatile organic compounds</p> Signup and view all the answers

    What is the primary function of thorns in plant defense?

    <p>Act as a mechanical barrier</p> Signup and view all the answers

    In what way do prickles differ from thorns and spines?

    <p>Prickles are outgrowths from the epidermis or cortex</p> Signup and view all the answers

    What is a key function of spines in cacti?

    <p>Reduce water loss</p> Signup and view all the answers

    Why have scientists emphasized studying plant defense mechanisms?

    <p>To understand plant interactions with other organisms</p> Signup and view all the answers

    Which of the following is a mechanical plant defense structure?

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

    What is the significance of understanding plant defense mechanisms for sustainable farming practices?

    <p>Develop more sustainable pest and disease management strategies</p> Signup and view all the answers

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