Explain why food needs to be digested before cells can use it for energy.

Food is necessary to digest because food we eat is made of macromolecules.

Explanation: Macromolecules such as carbohydrates, proteins and lipids which are made of many small molecules i. e. glucose, amino acid and fatty acid respectively. Our body absorb food in the form of glucose, amino acid and fatty acid so it is necessary that the food is broken down into these small molecules.