Question

Chemical process of digestion is initiated in the
A. Stomach by hydrolytic action of pepsin
B. Stomach by hydrolytic action of rennin
C. Oral cavity by hydrolytic action of pepsin
D. Oral cavity by hydrolytic action of salivary amylase

Answer 1

Hint: Digestion is the breakdown of big insoluble food particles into small water-soluble food particles so that they can be absorbed into the watery blood plasma. In specific organisms, these tiny materials are absorbed by the small intestine into the bloodstream.

Complete step-by-step answer:
In the oral cavity, the process of digestion begins as the salivary amylase functions on starch (complex polysaccharide) and converts it to maltose (disaccharide).
With the help of saliva, tongue and teeth masticate food and mix up the food completely.
Mucus in saliva assists in adhering and lubricating the masticated food particles into a bolus.
Then the bolus is transported into the pharynx and then into the oesophagus by deglutition or swallowing. Further, the bolus is transported through the oesophagus by successive waves of muscular contractions known as peristalsis. The gastro-oesophageal sphincter regulates the passage of food into the stomach.
The saliva secreted into the oral cavity includes enzymes and electrolytes, lysozyme and salivary amylase. The chemical process of digestion is started in the oral cavity by the hydrolytic action of carbohydrate separating enzyme, the salivary amylase. Approximately 30 percent of starch is hydrolysed by this enzyme into disaccharide-maltose.

Hence the correct answer is option d.

Note: Digestion is a simple process of breaking down food particles into smaller parts. This process starts from the mouth and is then transported to the stomach, to the small intestine, the large intestine, and then to the anus. This is the physical process of digestion.