The process of taking in food through the mouth is called: MCQ with Answer and Explanation

Explanation:
Secretin was the first hormone ever to be identified, marking the birth of endocrinology as a distinct field. It was discovered in 1902 by British physiologists William Bayliss and Ernest Starling. They observed that when acidic chyme entered the duodenum, it stimulated the pancreas to secrete bicarbonate-rich juice, even if all nerves to the pancreas were cut. They concluded that a chemical messenger (which Starling coined the term 'hormone' for in 1905) was released from the intestinal mucosa into the blood to stimulate the pancreas. They named this messenger secretin.

Explanation:
Nitrogen fixation is the conversion of inert atmospheric N₂ into ammonia (NH₃) by free-living (e.g., Azotobacter) or symbiotic (e.g., Rhizobium) bacteria, or by industrial processes. Nitrification is the oxidation of ammonia to nitrites then nitrates. Denitrification converts nitrates to N₂ gas. Ammonification is the release of ammonia from organic nitrogen by decomposers. Fixed nitrogen is essential for plant growth.

Explanation:
Trypsinogen is an inactive proenzyme secreted by the pancreatic acinar cells. Upon entering the small intestine (duodenum), it is specifically activated into the active enzyme trypsin by the enzyme enterokinase (also known as enteropeptidase), which is secreted by the intestinal mucosa. Trypsin then activates other pancreatic proenzymes like chymotrypsinogen and procarboxypeptidase. Pepsinogen is activated by HCl.