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GCE Biology 1989 Question 12

Question 12

Transport in Plants

The upward movement of the sap in the xylem vessel is brought about by

  1. A.transpiration stream
  2. B.guttation
  3. C.capillarity
  4. D.osmosis
  5. E.cohesion
Show the answer and explanation

Answer: A (transpiration stream)

Explanation

Water evaporating from the leaves pulls a continuous column of water up the xylem (transpiration pull); this is the main force raising sap.