(a)(i) What is a deficiency disease? (ii) Complete the table below by naming five nutrient deficiency diseases in humans and stating one remedy for each of ...

Answer Details

(a)(i) What is a deficiency disease?

A deficiency disease is a disease that results from the lack or inadequate supply of a particular nutrient (such as a vitamin or a mineral element) in the diet over a period of time.

(a)(ii) Five nutrient deficiency diseases and their remedies

(Night blindness from lack of vitamin A, corrected by eating carrots, red palm oil and green vegetables, is an acceptable alternative.)

(b) Chemical tests

(i) Test for starch in a tuber of yam

1. Place a small piece of the yam on a white tile.
2. Add two or three drops of iodine solution to it.
3. Observation: the yam turns blue-black.
4. Inference: starch is present.

(ii) Test for glucose in orange fruit

1. Put some orange juice into a test tube.
2. Add an equal volume of Benedict's (or Fehling's) solution.
3. Heat the mixture in a water bath (boil).
4. Observation: the blue colour changes through green and yellow to a brick-red precipitate.
5. Inference: a reducing sugar (glucose) is present.