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Flashcards · Biology

Plant Hormones

64 cards from 4 lessons

  1. What is phototropism?

    A growth response to light.

  2. What is gravitropism?

    A growth response to gravity, also called geotropism.

  3. Where is auxin made?

    In the tips of shoots and roots.

  4. What does auxin do in a shoot?

    Makes the cells elongate.

  5. What causes a shoot to bend towards light?

    More auxin on the shaded side, so the shaded side grows faster.

  6. What does unequal distribution of auxin cause?

    Unequal growth rates in roots and shoots.

  7. Where does auxin collect in a seedling on its side?

    On the lower side.

  8. Why does the shoot bend upwards?

    The lower side grows faster.

  9. Why does the root bend downwards?

    Auxin slows growth on the lower side, so the upper side grows faster.

  10. What type of phototropism does a shoot show?

    Positive, as it grows towards light.

  11. What type of gravitropism does a shoot show?

    Negative, as it grows away from gravity.

  12. What type of gravitropism does a root show?

    Positive, as it grows towards gravity.

  13. Why is phototropism useful?

    It puts the leaves in the best position for photosynthesis.

  14. Why is gravitropism useful in a root?

    It grows down to find water and mineral ions and anchor the plant.

  15. Why do plants respond more slowly than animals?

    Hormones travel slowly, and growth takes time.

  16. Common mistake about auxin?

    Saying it moves to the lit side. It moves to the shaded side.

  17. What is required practical 8?

    Investigate the effect of light or gravity on the growth of newly germinated seedlings.

  18. How must the results be recorded?

    As length measurements and as labelled biological drawings.

  19. What is the independent variable for light?

    The direction of the light.

  20. What is the dependent variable?

    The length and the direction of growth of the shoots or roots.

  21. Why is a tray kept in the dark?

    As a control, to show growth without light.

  22. Why are the gravity dishes kept in the dark?

    So that light does not affect the direction of growth.

  23. What does a clinostat do?

    Turns seedlings so gravity acts on all sides equally.

  24. Name two control variables.

    Any two from: type of seed, number of seeds, volume of water, temperature, distance from the lamp.

  25. What should a biological drawing have?

    Clear single lines, no shading, labels and a scale.

  26. What does a resolution of 1 mm mean?

    The ruler can detect changes of 1 mm.

  27. What does repeatable mean?

    The same person gets similar results.

  28. What does reproducible mean?

    Other people get similar results.

  29. How could the results be made more reliable?

    Use more seedlings and repeat the investigation.

  30. Why is the lamp a problem?

    It can warm the seedlings on one side.

  31. Why wash hands after the practical?

    Mould and bacteria can grow on damp seeds.

  32. Common mistake in a biological drawing?

    Using shading and colour, and not labelling the drawing.

  33. What are gibberellins important in?

    Initiating seed germination.

  34. What is seed dormancy?

    A resting state in which the seed does not germinate.

  35. What does ethene control?

    Cell division and the ripening of fruits.

  36. What state is ethene at room temperature?

    A gas.

  37. Why does ethene spread between fruits?

    It is a gas, so it moves through the air.

  38. What happens to fruit as it ripens?

    It becomes softer, sweeter and changes colour.

  39. Why does one ripe fruit spoil others?

    It makes ethene, which makes the others ripen.

  40. Do you need to know how gibberellins work?

    No, the mechanism is not required.

  41. What other effects do gibberellins have?

    Stimulate stem growth and flowering.

  42. Why does a seed need to be dormant?

    To avoid germinating at the wrong time of year.

  43. What is a germination control?

    Seeds treated in the same way but without the hormone.

  44. What does a fruit bag with ethene show?

    That ethene makes fruit ripen faster.

  45. Why is ripening useful to the plant?

    Animals eat ripe fruit, and carry the seeds.

  46. How is ripening slowed in stores?

    Keep the fruit cold, and remove the ethene.

  47. Name the hormone that makes shoots elongate.

    Auxin.

  48. Common mistake about ethene?

    Saying it is a liquid. It is a gas.

  49. How are auxins used as weed killers?

    They make broad-leaved weeds grow too fast, so they die.

  50. Why is an auxin weed killer selective?

    It kills broad-leaved weeds, but does not harm narrow-leaved crops or grass.

  51. How are auxins used in rooting powder?

    They make cuttings grow roots quickly.

  52. How are auxins used in tissue culture?

    They promote the growth of new plants from small pieces of tissue.

  53. How is ethene used in the food industry?

    To control the ripening of fruit during storage and transport.

  54. Why are some fruits picked unripe?

    They are firm, so they are not damaged during transport.

  55. How are gibberellins used on seeds?

    To end dormancy, so that they germinate.

  56. How are gibberellins used on plants?

    To promote flowering and to increase the size of fruit.

  57. What is horticulture?

    The growing of fruit, vegetables, flowers and garden plants.

  58. How can weed killers reduce biodiversity?

    They kill plants that support insects and birds.

  59. How can weed killers harm streams?

    They can be washed off by rain into the water.

  60. What is a clone?

    A genetically identical copy.

  61. Why must tissue culture be sterile?

    To prevent the growth of bacteria and fungi.

  62. How can fruit be stored for longer?

    Keep it cold and remove the ethene.

  63. Name an advantage of using plant hormones.

    Higher yields, even ripening, or many identical plants.

  64. Common mistake about auxin weed killers?

    Saying they kill all plants. They kill broad-leaved weeds.