Question

Why is digestion of food a chemical change?

Answer 1

Hint: The digestion of food is the process of breaking down of the complex nutrients present in the food to simpler ones by the help of enzymes. This process takes place in the alimentary canal starting from mouth to the large intestine. The undigested food is excreted out of the body through anus.

Complete answer:
We know that there are two types of changes:
Physical change: These changes affect the chemical substance but do not affect its composition. For example, melting ice.
The chemical change: These are the changes in which the composition of the chemical substances. For example, curding of milk, digestion of food.

Let us discuss the digestion of food as an example of chemical change. The process of digestion starts from the mouth where the carbohydrates present in the food is broken down into simpler carbohydrates. Then the food goes to the stomach and intestine where the proteins, lipids and carbohydrates are broken down into simpler and absorbable forms by the digestive enzymes secreted by liver, pancreas and stomach. This process is irreversible and the simpler molecules produced cannot be regained. The chemical property of the food is changes along with its physical form.
So we can say that digestion of food is a chemical change.

Note: Important enzymes which bring about the digestion process are-
1. Salivary amylase in the mouth which breaks down starch.
2. Pepsin, trypsin, chymotrypsin present in the stomach which breaks proteins.
3. Proteases, lipases secreted by the liver, intestine, pancreas helps in digesting the fats and proteins present in the food.