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WAEC Biology 2015 Question 23

Question 23

Food Substances and Enzymes

A student used the following steps in testing for a non-reducing sugar: I. added Benedict's solution to the sugar solution; II. added dilute hydrochloric acid to the sugar solution and boiled it; III. added sodium hydroxide solution to the solution in II and boiled; IV. added Benedict's solution to the cooled solution in III.
What is the importance of step III in the testing process? To

  1. A.neutralize the sugar solution.
  2. B.soften the sugar solution.
  3. C.change the colour of the sugar solution.
  4. D.increase the acid content of the sugar solution.
Show the answer and explanation

Answer: A (neutralize the sugar solution.)

Explanation

Sodium hydroxide neutralises the acid added in step II. Benedict's solution works only in a neutral or slightly alkaline solution.