Question

Where are proteins first digested in the alimentary canal?
a) Small intestine
b) Oesophagus
c) Mouth
d) Stomach

Answer 1

Hint: Protein is a macronutrient that is essential for building muscle mass. It is commonly found in animal products, although it is also present in other sources, such as nuts and legumes. There are three macronutrients: protein, fat and carbohydrate. Macronutrients supply calories or energy.

Complete answer:

Mechanical protein digestion begins in the mouth and continues in the stomach and small intestines. Chemical protein digestion begins in the stomach and ends in the small intestine. The body recycles amino acids to make more protein. 

The digestion of the food begins in the mouth where the enzyme amylase is secreted, which digests the start of the food and converts it to maltose. From there, through the esophagus, the food comes to the stomach, where it is stored for 4 hours and mixed with acid.

Food when it comes to the stomach where the wall of the stomach secretes HCl with a pH of 1.8. This acid activates the inactive pepsinogen enzyme and forms active pepsin, which digests proteins and converts them to proteins and peptides.

From here, the food moves to the small intestine, where the secretion of the liver and pancreas reaches through the hepatopancreatic duct, which is alkaline in nature and neutralizes the acidic food that comes from the stomach. Here the majority of protein digestion takes place in amino acids, fat in fat droplets, polysaccharides in monosaccharides, etc.

Thus, the correct answer is option C: Mouth

Note:

Mechanical and chemical digestion takes place in the mouth and stomach respectively. The stomach releases gastric juices containing hydrochloric acid and pepsin, the enzyme that initiates the chemical digestion of proteins. Muscular contractions, known as peristalsis, also aid in digestion. Powerful stomach contractions churn the partially digested protein into a more uniform mixture called chyme.