Question

What is digestion? Why do only animals require a digestive system?

Answer 1

Digestion is the process of breaking down complex food materials into simpler substances by the action of enzymes.

Need for a digestive system:

(i) Large complex molecules like carbohydrates, proteins and lipids need to be broken down to simpler molecules. These simpler molecules can then be absorbed and utilized by the body.

(ii) The breaking down of complex food molecules into their simpler form is possible only through the process of digestion.

(iii) During digestion, large complex macromolecules present in food are converted into small simpler molecules, which can be simplified in different compartments of digestive system only.