What are the hydrolysis products of
(i) sucrose and (ii) lactose?

Sucrose on hydrolysis gives glucose and fructose.
(i) 

Lactose on hydrolysis gives glucose and galactose.
(ii) 

Mono-saccharides: Ribose, 2-deoxyribose, galactose, fructose.

Di-saccharides: maltose, lactose.

A reducing sugar is any sugar that is capable of acting as a reducingagent because it has a free aldehyde group or a free ketone group. All monosaccharides are reducing sugars. 

(i) They serve as structural materials for cell walls. For example, the polysaccharide cellulose is the chief constituent of the plant cell wall.

(ii) Carbohydrates act as biofuels and provide energy for different functioning.