The question asks about the nutrient whose digestion begins in the mouth. We need to recall the initial sites of digestion for different macromolecules in the human digestive system.
Correct Option: D) Carbohydrates
The question asks to identify the organ responsible for secreting the enzyme pepsin, which is involved in protein digestion. This requires knowledge of the digestive system and the specific functions of its organs.
Therefore, the stomach is the organ that secretes pepsin.
Correct Option: B) The stomach is the primary site where protein digestion begins, and it secretes pepsin (as pepsinogen) to carry out this function.
The question asks to identify the organ responsible for producing bile and the structure where it is stored. This requires knowledge of the basic functions of the digestive system organs.
Based on these physiological facts, the liver produces bile, and the gallbladder stores it.
Correct Option: D) Liver; stored in gallbladder
This question tests knowledge about the anatomy of the human digestive system, specifically the relative lengths of its components. To answer correctly, one needs to recall the typical lengths of the oesophagus, stomach, small intestine, and large intestine.
Correct Option: B) Small intestine
The question asks about the primary site of fat digestion in the human digestive system. To answer this, we need to recall the roles of different organs in the digestion process, specifically focusing on fat breakdown.
Correct Option: C) Small intestine
The question asks to identify the specific type of cell within the gastric glands responsible for secreting hydrochloric acid (HCl). This requires knowledge of the different cell types found in the stomach lining and their respective functions.
The gastric glands contain several types of cells, each with a distinct function:
Based on this information, parietal (oxyntic) cells are the ones that secrete hydrochloric acid.
Correct Option: A) Parietal (oxyntic) cells are specialized cells in the gastric glands that secrete hydrochloric acid (HCl) and intrinsic factor.