Question

In which organ the digestion of protein starts in the human digestive tract?
A.Mouth
B.Oesophagus
C.Stomach
D.Small intestine

Answer 1

Digestion is an important life process by which nutrition is obtained from the food we ingest. It is majorly marked by the breakdown of complex organic molecules into simple molecules like glucose. Digestion starts in the mouth by salivary glands and finishes in the small intestines with the absorption of dissolved nutrients. Proteins are digested by pepsin enzymes secreted along with hydrochloric acid.

Complete answer: Digestion is an important process that needs to take place at regular intervals whenever we ingest food. The food consists of various nutrients. Nutrients are complex molecules that are broken down during digestion into simpler molecules. These molecules can be sugars like glucose or fatty acids. The walls of the small intestine absorb these essential molecules and circulate throughout the body for energy production.
Digestion involves specific enzymes that act on the specific type of molecules. For proteins, it is the enzyme pepsin that digests them. Pepsin is secreted by the stomach chief cells in the stomach along with hydrochloric acid. Thus, protein digestion occurs in the stomach of the human digestive tract. Proteins are the most complex molecules and undergo further digestion in the small intestine. Both pepsin and hydrochloric acid make up the digestive juice in the stomach. Pepsin only causes partial protein digestion that converts the proteins into smaller molecules called peptides. Further digestion occurs through pancreatic enzymes. Some of the partially digested protein is also absorbed through the small intestine.
Thus, we can conclude that the right answer is option C) Stomach

Note: Digestion can be divided into four major phases. These phases are named as ingestion of food, mechanical and chemical breakdown of food, absorption, and then excretion. Peristalsis is the major mechanical force or movement that allows food to travel from the esophagus to the final excretory system.