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WAEC Biology 2016 Question 21

Question 21

Photosynthesis and Plant Nutrition

The steps below are involved in the testing of a leaf for starch: I. Decolorize leaf II. Dip decolorized leaf in warm water III. Place leaf in boiling water IV. Add iodine solution
The correct order for the test is

  1. A.I, II, III and IV.
  2. B.I, III, II and IV.
  3. C.II, III, I and IV.
  4. D.III, I, II and IV.
Show the answer and explanation

Answer: D (III, I, II and IV.)

Explanation

First boil the leaf in water to kill and soften it (III), then decolourise it in alcohol (I), dip it in warm water to soften it again (II), and finally add iodine (IV).