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CAIE A Level Biology 9700

Transport in plants questions

Exam-style questions on Transport in plants, ordered from foundation to challenge. Pick one, write your answer the way you would in the exam, and it comes back marked against the mark scheme, point by point.

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Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.

  1. Describe4 marksStandardDescribe the distribution of xylem and phloem in transverse sections of a young (primary) herbaceous dicotyledonous plant stem and root. Your description should include the relative positions of these tissues to each…
  2. Explain5 marksStandardA student examines a transverse section of a stem from a herbaceous dicotyledonous plant. The xylem vessel elements are observed under a microscope. Explain how the structure of these xylem vessel elements is adapted…
  3. Describe5 marksStandardIn a herbaceous dicotyledonous plant, the xylem and phloem are responsible for long-distance transport. Describe the structure of xylem vessel elements and phloem sieve tube elements (including companion cells). In…
  4. Describe5 marksStandardA student treats a plant root with an enzyme that digests the suberin in the Casparian strip. Explain the role of the Casparian strip in the transport of water from the soil to the xylem, with reference to the apoplast…
  5. Explain4 marksStandardExplain the differences in the arrangement of xylem and phloem in transverse sections of a herbaceous dicotyledonous root and a herbaceous dicotyledonous stem.
  6. Compare5 marksStandardCompare the apoplast and symplast pathways for the transport of water across the root cortex to the xylem. In your answer, explain the role of the Casparian strip in the endodermis.
  7. Compare5 marksStandardA student investigated the effect of environmental conditions on transpiration rate in a leafy shoot of a mesophyte plant. The transpiration rate was measured gravimetrically over one-hour periods. The mean rates for…
  8. Compare5 marksStandardAn electron micrograph of a transverse section through the stem of a tomato plant shows two adjacent cells in the phloem: a sieve tube element and a companion cell. Compare the structure of a companion cell with that…
  9. Compare5 marksStandardA student immerses the roots of a young tomato plant in a solution containing a blue dye. After 30 minutes, they cut a thin cross-section of the root and observe under a microscope. They see that the dye is present in…
  10. Describe5 marksStandardA student used a potometer to measure the rate of transpiration from a leafy shoot under four different environmental conditions. The results are shown in the table. Condition Transpiration rate (arbitrary units) A…
  11. Compare4 marksStandardCompare the structural adaptations of a xylem vessel element and a phloem sieve tube element for their respective transport functions. In your answer, explain why the sieve tube element depends on the companion cell.
  12. Explain4 marksStandardA tall tree transpires rapidly on a hot, dry day. Explain how water is transported up the xylem from the roots to the leaves.
  13. Compare4 marksStandardIn a herbaceous dicotyledonous plant, phloem tissue contains two types of living cells: sieve tube elements and companion cells. These cells have distinct structures but work closely together. Compare the structure of…
  14. Describe5 marksStandardMarram grass (Ammophila arenaria) is a xerophyte that grows in dry, windy sand dunes. Its leaves are rolled, have a thick cuticle, and sunken stomata in grooves. Describe the structural adaptations of a xerophyte leaf…
  15. Describe4 marksStandardDescribe the distribution of xylem and phloem in transverse sections of a young root and a young stem of a herbaceous dicotyledonous plant.
  16. Explain4 marksStandardIn a transverse section through the leaf of a herbaceous dicotyledonous plant, the vascular bundles (veins) show a characteristic arrangement of xylem and phloem. Explain how the distribution and structure of xylem and…
  17. Explain5 marksStandardA student observes a transverse section of the stem of a young herbaceous dicotyledonous plant. The xylem vessels appear as large, thick-walled cells with no living contents. Using your knowledge of the structure of…
  18. Explain4 marksStandardIn an investigation into phloem transport, researchers isolated leaf discs from a plant and measured the uptake of radioactive sucrose into sieve tubes. They found that adding an inhibitor of ATP synthesis (such as…
  19. Compare5 marksStandardAn electron micrograph of phloem tissue from a herbaceous dicotyledonous plant shows two adjacent cells: a sieve tube element and a companion cell. Compare the structure of these two cells and explain how each cell's…
  20. Outline4 marksStandardIn a plant, sucrose produced in leaf mesophyll cells must be loaded into phloem sieve tubes for transport to sinks. Companion cells adjacent to sieve tubes play a key role in this process. Outline how companion cells…
  21. Describe5 marksStandardMarram grass (Ammophila arenaria) is a xerophyte that grows in dry, windy sand dunes. Describe five structural adaptations of its leaves that reduce water loss by transpiration, and explain how each adaptation reduces…
  22. Outline4 marksStandardA student adds a blue dye to the water surrounding the roots of a young bean plant. After 30 minutes, a cross-section of the root is examined under a microscope. The dye is observed in the cell walls of the cortex but…
  23. Explain4 marksStandardDescribe the transverse section of a herbaceous dicotyledonous leaf. In a typical leaf, the vascular bundles contain xylem and phloem. Explain how the structure of xylem vessel elements is adapted for the transport of…
  24. Compare4 marksStandardSieve tube elements and companion cells are two distinct cell types found in the phloem of herbaceous dicotyledonous plants. (a) Compare the structures of a sieve tube element and a companion cell. (b) Explain why a…
  25. Explain4 marksStandardIn a tall tree, water is transported from the roots to the leaves through the xylem. Explain how the cohesion-tension mechanism, involving the properties of water and the structure of xylem, enables this transport.
  26. Compare5 marksStandardA student prepared a transverse section of a stem from a young sunflower plant (a herbaceous dicotyledon) and observed the phloem under a light microscope. The student focused on the two types of cells that make up the…
  27. Explain4 marksStandardA student investigates water uptake in a plant root. They place a root in a dilute solution of a water-soluble dye. They observe that the dye moves through the cell walls of the outer root tissues but is stopped at a…
  28. Describe5 marksStandardA student examines a transverse section of a herbaceous dicot stem under a light microscope. They observe xylem vessel elements and phloem sieve tube elements with their associated companion cells. Describe the…
  29. Describe5 marksStandardA student investigated the effect of four different environmental conditions on the rate of transpiration of a plant. The relative transpiration rate (arbitrary units) was measured under each condition. The results are…
  30. Describe5 marksStandardDescribe the structural features of xylem vessel elements and phloem sieve tube elements and companion cells in a herbaceous dicotyledonous plant, and explain how each feature is related to the function of these cells.
  31. Compare5 marksStandardA student examined transverse sections of leaves from two plants: Species X, a xerophyte adapted to arid conditions, and Species Y, a mesophyte from a temperate woodland. The following features were noted in Species X…
  32. Outline6 marksChallengeA researcher studying phloem transport in a flowering plant observes that treating leaves with an inhibitor of plasma membrane H+-ATPases (proton pumps) causes a rapid decrease in the concentration of sucrose in the…
  33. Compare6 marksChallengeWater moves from the soil into the xylem of roots via two main pathways: the apoplast pathway and the symplast pathway. Compare these two pathways for water transport from root hairs to the xylem vessels. In your…
  34. Describe5 marksChallengeA xerophyte plant has leaves that are structurally adapted to reduce water loss by transpiration. Describe five structural features of such leaves and explain how each feature helps to reduce the rate of transpiration.
  35. Explain6 marksChallengeA student investigates water transport in a herbaceous dicotyledonous plant, such as sunflower. Transverse sections of the stem, root, and leaf are examined using a photomicrograph. In the stem, xylem vessels are…
  36. Explain5 marksChallengeExplain how water is transported from the soil to the xylem of a plant, with reference to the apoplast and symplast pathways, and describe the mechanism that moves water up the xylem to the leaves.
  37. Compare7 marksChallengeThe table shows the transpiration rates of a xerophyte plant, Agave, under three different environmental conditions. Condition Transpiration rate (mg water per cm² leaf per hour) A: still air, 20°C, 40% relative…
  38. Explain6 marksChallengeIn a herbaceous dicotyledonous plant, water is transported from roots to leaves under tension created by transpiration. The xylem vessel elements are highly specialised cells. Using your knowledge of the structure of…
  39. Compare7 marksChallengeA student measured the transpiration rate (arbitrary units) of two plant species, X (a typical mesophyte) and Y (a xerophyte), at different times of day under the same environmental conditions. The results are shown in…
  40. Explain6 marksChallengeA student is studying a photomicrograph of a transverse section of a leaf from a herbaceous dicotyledonous plant. The vascular bundles in the midrib show xylem positioned towards the upper (adaxial) epidermis and…
  41. Describe5 marksChallengeA student prepared stained transverse sections of a young root and a young stem from a herbaceous dicotyledonous plant. Describe the differences in the distribution of xylem and phloem in these two sections, and…
  42. Compare7 marksChallengeCompare the structure of a companion cell with that of a xylem vessel element in a herbaceous dicotyledonous plant. In your answer, describe the key structural differences and explain how each cell’s features are…
  43. Describe5 marksChallengeA student is examining a photomicrograph of a transverse section of a herbaceous dicot stem. They identify xylem vessel elements and phloem sieve tube elements. Describe the structural features of xylem vessel elements…
  44. Compare7 marksChallengeCompare the structure of a phloem sieve tube element and a companion cell in a herbaceous dicotyledonous plant. For each cell, explain how its structural features relate to its role in the transport of organic solutes.
  45. Compare7 marksChallengeA student is examining transverse sections of a herbaceous dicotyledonous plant and observes the structure of xylem vessel elements and phloem sieve tube elements. Compare the structure of xylem vessel elements and…
  46. Explain5 marksChallengeA researcher studies water transport in maize (Zea mays) roots. A fluorescent dye applied to root hairs is observed to move through cell walls initially, but at the endodermis it shifts to the cytoplasm and then enters…
  47. Compare5 marksChallengeA xerophyte shrub grows in an arid environment. Its leaves are small and thick, with a thick waxy cuticle. The stomata are sunken in pits on the lower epidermis, and there is a dense covering of trichomes (hairs) on…
  48. Outline5 marksChallengeOutline the pathway taken by water from the soil to the xylem of a plant root, describing how the apoplast and symplast routes differ in their use of cell structures.
  49. Explain7 marksChallengeA researcher investigating water transport in a 60 m tall Douglas fir tree measured the diameter of the trunk at 1.5 m above ground every hour during a clear summer day. She found that the trunk diameter decreased…
  50. Describe5 marksChallengeA student examines prepared slides of transverse sections of a root and a stem from a herbaceous dicotyledonous plant (e.g., a sunflower). Describe the distribution of xylem and phloem visible in each section, and…
  51. Compare7 marksChallengeA student examines a stained transverse section of a stem from a herbaceous dicotyledonous plant under a light microscope. They identify vascular bundles containing xylem and phloem. The student notes that xylem vessel…
  52. Explain6 marksChallengeA student prepared a transverse section of a leaf from a herbaceous dicotyledonous plant and observed the midrib region under a microscope. The following features were noted: In the centre of the midrib, there is a…
  53. Describe5 marksChallengeDescribe the structural features of xylem vessel elements and phloem sieve tube elements in a herbaceous dicotyledonous plant, and explain how each feature relates to their respective functions. Present your answer in…
  54. Describe6 marksChallengeDescribe the pathway of water from the soil to the xylem in a plant root, explaining the role of the Casparian strip at the endodermis.
  55. Outline7 marksChallengeA tall tree is actively transpiring on a warm day. Outline the process of water transport from the soil to the leaves, explaining how cohesion and adhesion contribute to the movement of water up the xylem.
  56. Explain6 marksChallengeXylem vessel elements in herbaceous dicotyledonous plants are highly adapted for the transport of water and mineral ions. With reference to specific structural features, explain how xylem vessel elements are suited to…
  57. Outline6 marksChallengeOutline the mechanism by which companion cells in plant leaves actively load sucrose into phloem sieve tubes, describing the roles of proton pumps and cotransporter proteins.
  58. Describe5 marksChallengeIn a herbaceous dicotyledonous plant, the arrangement of vascular tissues differs between the stem and the root. In a transverse section of a young stem, vascular bundles are found in a ring near the periphery. Each…