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Mass Transport in Plants

OCR AS-level BiologyTopic 9 of 1218 lessons

Revision notes for Mass Transport in Plants in OCR Biology A (H020). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

  1. Specialised Plant CellsRoot hair cells are epidermal cells with extensions of the cell wall and cytoplasm called root hairs.
  2. TranspirationWater uptake by plants is through the roots.
  3. Movement of Water into the Root Hair CellsIf the concentration of mineral ions in the soil is higher than the concentration of mineral ions in the root hair cell, then mineral ions are taken…
  4. Movement of Water across the RootsWater and mineral ions are taken up by the root hair cells.
  5. Movement of Water Up the StemThe movement of water up the stem is through cohesion-tension.
  6. Movement of Water Across the LeafWater moves from the xylem to the mesophyll cells by osmosis.
  7. Movement of Water Through the StomataStomata are pores in the leaves caused by the curvature of adjacent guard cells.
  8. TranslocationTranslocation is the movement of organic substances and some minerals from one part of the plant to another.
  9. Phloem LoadingActive phloem loading uses the apoplast pathway and uses energy and membrane-bound co-transporter protein and a proton pump to move sucrose into the…
  10. Mass Flow through Sieve Tube ElementsSucrose loaded into the sieve tubes causes the sieve tubes to have a lower water potential.
  11. Mass Flow ModelThe mass flow hypothesis explains translocation: sucrose solution moves through the phloem from a source, where sucrose is made and loaded, to a…
  12. Phloem UnloadingSucrose is actively transported out of the sieve tubes into the sink cells.
  13. Ringing ExperimentsA ring of cells is removed from the outer layer of a tree.
  14. Tracer ExperimentsRadioactive isotopes are used to trace the movement of substances in plants.
  15. Evidence for Translocation in PhloemA summary of the evidence for translocation in phloem is listed below: 1.
  16. XerophytesMost plants have features that enable them to conserve water such as a waxy cuticle and stomata on the underside of the leaf that can be closed to…
  17. Limiting Water Loss in PlantsPlants need a large surface area to volume ratio to maximise photosynthesis and to capture as much light as possible.
  18. HydrophytesHydrophytes are plants that live in water.

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