Answer the following questions briefly:
(i) What are reducing sugars?
(ii) What is meant by denaturation of a protein?
(iii) How is oxygen replenished in our atmosphere?

Explanation

Reducing sugar: All those carbohydrates which reduce Fehling.s solution and Tollens. reagent are referred to as reducing sugars. All monosaccharides whether aldose or ketose are reducing sugars.
(ii) Denaturation of a protein: When `2^(@) and 3^(@)` structure of a protein is destroyed due to the physical changes like temperature, change in pH, it is called denaturation of a protein. Example: Coagulation of egg white on boiling.
(iii) We take oxygen atmosphere and release `CO_(2)`. Plants take up `CO_(2) and H_(2)O` from the atmosphere to prepare their food in the presence of sunlight and release `O_(2)`, thus `O_(2)` is replenished in atmosphere.