passwella.
Menu

WAEC Biology 2015 Question 24

Question 24

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.
The colour change to be observed in step IV is

  1. A.blue-black.
  2. B.brick red.
  3. C.purple.
  4. D.violet.
Show the answer and explanation

Answer: B (brick red.)

Explanation

After hydrolysis there are reducing sugars, so boiling with Benedict's solution gives a brick-red (orange-red) precipitate.