The body uses two types of digestion, mechanical and chemical, to break down food into small components. Mechanical digestion physically breaks down pieces of food, whereas chemical digestion breaks down food on the molecular level. Why must food molecules be chemically broken down into smaller component molecules by the body?

So food must be broken down into smaller molecules before it can be absorbed through the blood and transported to cells throughout the body.

Explanation:

Digestion in humans is the process by which food and drink are broken down into smaller parts so that the body can use them as a source of energy to form and maintain tissues. It starts in the mouth, when we chew and eat, that is called mechanical digestion. And it ends in the small intestine, that's called chemical digestion. Although the chemical process varies depending on the kind of food.

So food must be broken down into smaller molecules before it can be absorbed through the blood and transported to cells throughout the body. Then the polymers (large molecules such as carbohydrates, proteins or lipids) are degraded into the simpler components called monomers (monosaccharides, amino acids, glycerol and fatty acids). These monomers are the ones that the body can absorb for use, it cannot do so with large, complex molecules.

They need to be broken down into monomers to build new polymers that the body can use, and into molecules small enough to cross the cell membrane.

Explanation:

It should be understood that the two major types of digestion are chemical and mechanical digestions.

It should be noted that during the mechanical digestion, the food is physically broken down into smaller pieces, while the chemicals produced by the body break foods into their smaller chemical building blocks during the chemical digestion.

It should be known that both mechanical and chemical digestions start the same way , that is, from the mouth, and that most mechanical digestion and some chemical digestion occurs in the stomach.

Therefore, the major reasons why the foods are needed to be digested or broken down are the options given above.