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Flashcards · Biology

Plant Defences and Disease

48 cards from 3 lessons

  1. What is the leaf cuticle?

    A waxy layer on the outside of the epidermis.

  2. How does the cuticle protect a leaf from pathogens?

    It is waterproof and tough, so water and pathogens cannot easily get in.

  3. What is the cell wall made of?

    Cellulose.

  4. How does the cell wall protect the plant?

    It is rigid and strong, and difficult for pathogens to break through.

  5. How can a plant strengthen its cell wall when attacked?

    By laying down extra material at the point of infection.

  6. What is bark?

    A layer of dead cells that protects the trunk and branches.

  7. Give an example of a plant with thorns.

    Rose, hawthorn or cactus.

  8. What do hairs on leaves do?

    They deter insects and grazing animals.

  9. What is mimicry in plants?

    Looking like something unappetising, such as the passion flower that mimics butterfly eggs.

  10. Why can stomata be a weak point?

    Pathogens can enter the leaf through them.

  11. What do guard cells do?

    Open and close the stomata.

  12. How do plants protect their stomata from bacteria?

    They close them when they detect bacteria.

  13. Why does the cuticle make it harder for fungal spores?

    They need water to germinate, and the waxy surface stays dry.

  14. What is a pest?

    An organism that damages a plant.

  15. Why can plants not rely only on physical barriers?

    Pathogens can still enter through stomata or wounds.

  16. What is the common mistake about the cuticle?

    Saying it is made of cellulose. It is made of wax.

  17. Why do plants make chemicals?

    To defend themselves against pests and pathogens.

  18. Name three types of chemical defence.

    Poisons, antibacterial or antifungal chemicals, and bitter deterrents.

  19. Which plant gave aspirin?

    The willow.

  20. What is aspirin used for?

    Pain relief and reducing fever.

  21. Which plant gave digitalis?

    The foxglove.

  22. What is digitalis used for?

    Treating some heart conditions.

  23. Which plant gives morphine?

    The opium poppy.

  24. What is morphine used for?

    Severe pain.

  25. Which plant gave artemisinin?

    Sweet wormwood.

  26. What is artemisinin used for?

    Treating malaria.

  27. Which tree gave the cancer drug taxol?

    The yew.

  28. How can you test whether a plant extract is antibacterial?

    Put a disc soaked in it on an agar plate of bacteria, and look for a clear zone.

  29. What does a zone of inhibition show?

    The extract stopped bacteria growing in that area.

  30. Why is a control disc used?

    To show that the solvent alone has no effect.

  31. Why are some plant chemicals made only when the plant is attacked?

    It saves energy and resources.

  32. Common mistake about plant medicines?

    Thinking that natural plant medicines are always safe. Many are poisonous in large doses.

  33. How are plant diseases first detected in the field?

    By observing the symptoms.

  34. Give two symptoms of plant disease.

    Leaf spots, yellowing, wilting, mould or stunted growth.

  35. Why must environmental causes be eliminated?

    Damage can be caused by a lack of minerals, water or frost, and not by a pathogen.

  36. How can a mineral deficiency be tested?

    A soil test, or adding fertiliser to see if the plants recover.

  37. What does yellowing of leaves suggest?

    A lack of magnesium or nitrate, or a disease.

  38. What does a cluster of affected plants spreading outward suggest?

    A pathogen that is spreading.

  39. What does even damage across a field suggest?

    An environmental cause such as soil or weather.

  40. Why is a random sample used?

    It is not possible to check every plant, and a random sample avoids bias.

  41. Name four laboratory tests used to identify a plant pathogen.

    Microscopy, culturing, DNA testing and antibody tests.

  42. What is a monoclonal antibody test kit?

    A kit with antibodies that bind to one pathogen, giving a visible result.

  43. What can be seen under a microscope in an infected leaf?

    Fungal threads, spores or bacteria.

  44. Why is DNA testing useful?

    It is very accurate, and it can identify viruses.

  45. What did the map of ash dieback show?

    The disease spreading from one area, which suggested a pathogen.

  46. Why do farmers grow healthy plants of a control, in an investigation?

    To compare with the unhealthy plants.

  47. How can you estimate the number of diseased plants in a field?

    Find the percentage in a random sample and apply it to the whole field.

  48. Common mistake about plant disease?

    Assuming that all damage is caused by a pathogen.