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Flashcards · Biology

Plant Structures and Transport

68 cards from 4 lessons

  1. How do root hair cells take up water?

    By osmosis.

  2. How do root hair cells take up mineral ions?

    By active transport.

  3. Why do root hair cells have many mitochondria?

    To release energy from respiration for active transport.

  4. How is a root hair cell adapted for absorbing water?

    Its long thin extension gives a large surface area.

  5. What does xylem carry?

    Water and mineral ions from the roots to the stems and leaves.

  6. Why are xylem cells hollow?

    They have lost their contents and cross-walls, so water can flow through them as continuous tubes.

  7. What is lignin for?

    It strengthens the xylem walls so they do not collapse.

  8. What is transpiration?

    The loss of water vapour from the leaves, mainly through the stomata.

  9. What is the transpiration stream?

    The movement of water from the roots up the xylem to the leaves.

  10. Why is transpiration useful?

    It brings water for photosynthesis and minerals, cools the leaf and keeps cells firm.

  11. What do stomata and guard cells control?

    Gas exchange and water loss.

  12. How does a higher temperature affect transpiration?

    It increases the rate.

  13. How does high humidity affect transpiration?

    It decreases the rate.

  14. How does more air movement affect transpiration?

    It increases the rate, by removing water vapour.

  15. How does brighter light affect transpiration?

    It increases the rate, because the stomata open wider.

  16. A plant with a pointer marked X to the xylem in the stem. Name the part marked X and say what it carries.

    The xylem. It carries water and mineral ions from the roots to the leaves.

  17. A plant with arrows and no labels. Label the parts of this plant and what moves where. The same plant with every part labelled.

    Water from the soil, root hair cell, xylem carrying water and mineral ions up, leaf, stoma, water vapour out.

  18. What is translocation?

    The movement of dissolved sugars through the phloem.

  19. What does phloem carry?

    Dissolved sugars (food made by photosynthesis).

  20. Where does phloem carry sugars from?

    From the leaves, where they are made, to the rest of the plant.

  21. Why do roots need sugars from the leaves?

    They cannot photosynthesise, but need energy and materials to grow.

  22. Name two ways the sugars are used.

    For immediate use in respiration and growth, or stored.

  23. Is phloem made of living or dead cells?

    Living cells.

  24. How does cell sap move from one phloem cell to the next?

    Through pores in the end walls.

  25. In which directions does phloem carry sugars?

    Both up and down the plant.

  26. What does xylem carry?

    Water and mineral ions, from the roots to the leaves.

  27. Which tissue is made of dead cells?

    Xylem.

  28. Which tissue has pores in the end walls?

    Phloem.

  29. Which tissue is strengthened with lignin?

    Xylem.

  30. Where can sugars be stored in a plant?

    In roots, tubers and fruits.

  31. What would happen if the phloem were cut all round a trunk?

    Sugars could not reach the roots, so the roots and then the tree would die.

  32. Do you need to know the detailed structure of phloem or how it works?

    No. It is not required.

  33. A xylem vessel and a phloem tube with a pointer marked X to the phloem. Name the tissue shown on the right, and say what it carries.

    Phloem. It carries dissolved sugars up and down the plant, in a process called translocation.

  34. A xylem tube and a phloem tube with no labels. Label the xylem and the phloem. The same tubes with their labels and the direction of flow.

    Xylem: hollow dead cells with lignin, carries water and ions up. Phloem: living cells with pores in the end walls and companion cells, carries sugars up and down.

  35. What is the leaf?

    A plant organ, made of several tissues working together.

  36. Which tissue covers the surface of a leaf?

    The epidermis.

  37. What is the waxy cuticle for?

    It reduces water loss from the leaf.

  38. Where is most photosynthesis carried out in a leaf?

    In the palisade mesophyll.

  39. Why is the palisade mesophyll near the top of the leaf?

    That is where most light arrives.

  40. Why does the palisade mesophyll contain many chloroplasts?

    To absorb as much light as possible for photosynthesis.

  41. What is special about the spongy mesophyll?

    It has air spaces between the cells, which let gases diffuse and give a large surface area.

  42. What do the xylem and phloem do in a leaf?

    Xylem brings water and minerals in, and phloem carries sugars away.

  43. What is a stoma?

    A tiny pore in the lower epidermis that lets gases in and out.

  44. What do guard cells do?

    They open and close the stomata.

  45. When do guard cells close the stomata?

    When the plant is short of water.

  46. Why does closing the stomata help the plant?

    It stops more water being lost by evaporation.

  47. What is meristem tissue?

    Tissue at the tips of shoots and roots whose cells divide and can become any type of plant cell.

  48. Why are there more stomata on the underside of a leaf?

    It is cooler and shadier, so less water is lost.

  49. Why is the upper epidermis transparent?

    So that light can pass through to the palisade cells.

  50. A leaf cross-section with a pointer marked X to the palisade mesophyll. Name the tissue marked X and say what it does.

    The palisade mesophyll. Its tall cells are full of chloroplasts and carry out most of the photosynthesis.

  51. A leaf cross-section with no labels. Label every tissue in this leaf. The same leaf section with every part labelled.

    Waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, air space, xylem, phloem, guard cell, stoma and lower epidermis.

  52. What does a potometer measure?

    The rate of water uptake by a shoot, which estimates transpiration.

  53. Why is the shoot cut under water?

    To stop air getting into the xylem and blocking it.

  54. What does the air bubble show?

    How much water the shoot has taken up.

  55. How do you work out the rate of uptake?

    Distance moved by the bubble ÷ time.

  56. What is the independent variable if you move a lamp?

    The distance of the lamp (the light intensity).

  57. What is the dependent variable in a potometer experiment?

    The distance the bubble moves in a set time.

  58. Name two control variables.

    Any two of the same shoot, same time, same temperature, same light or wind.

  59. Why repeat the experiment?

    To check the results are reliable and to calculate a mean.

  60. How can you increase the humidity around the shoot?

    Cover it with a clear plastic bag.

  61. Why is water uptake only an estimate of transpiration?

    Some of the water is used in photosynthesis and growth.

  62. How do you find the volume of water taken up?

    π r² × the distance the bubble moves.

  63. How do you make an impression of the stomata?

    Paint clear nail varnish on the leaf, then peel it off with sticky tape.

  64. How do you calculate the stomatal density?

    The number of stomata ÷ the area of the field of view.

  65. Why must the joints of the potometer be airtight?

    So that no air enters, which would move the bubble.

  66. What would a fan do to the rate?

    Increase it, by removing water vapour from around the leaf.

  67. A potometer with a pointer marked X to the air bubble. Name the part marked X and say what it shows.

    The air bubble. It moves along the capillary tube as the shoot takes up water, so its distance shows the water taken up.

  68. A potometer with no labels. Label the parts of the potometer. The same potometer with every part labelled.

    Leafy shoot, cut stem, airtight seal, air bubble, capillary tube, ruler and water reservoir.