Describe the role played by each of the following in human beings

a) Proteins.
-Used for growth;
-Used for repair of worn-out tissues/ cells;
-They provide energy during starvation;
-Some are metabolic regulators (e.g. enzymes and hormones);
-Structural proteins are important components of various supportive tissues (e.g. bone and cartilage tissues and cell membrane is made up of protein);
-They are used in the body to bind and transport specific molecules from one part of the body to another;
-Some (e.g. antibodies) provide protection/ defense against infections/ diseases;
b)Carbohydrates.
-They are structural compounds (e.g. cellulose is a component of plant cell walls);
-They are oxidized to yield energy;
c)Lipids.
-They are structural components (e.g. cell membrane is made up of lipids and proteins);
-They insulate the body against heat loss (e.g. adipose tissue in the skin);
-They are oxidized to produce energy;
-They are a source of metabolic water when oxidized;
-They are deposited around some body organs (e.g. heart and kidney) to act as shock absorbers/ protect them against mechanical/ physical damage;
d)Vitamins.
-They form co-enzymes which activate enzymes;
-They defend the body against infections;
e) Water.
-They maintain the shape of the eyes;
-It acts as a universal solvent;
-It is a medium for chemical reactions;
-It is used as a coolant;
-It acts as a medium of transport;
-It is used to hydrolyze many body substances;