Question

Digestion of starch starts from
A. Stomach B. Intestine C. Oesophagus D. Mouth

Answer 1

Hint: The digestion starts within the mouth or cavum with carbohydrate begins. The salivary glands within the mouth secrete saliva, which helps to moisten the food. When the food is chewed then the salivary glands release the enzyme salivary amylase. It begins the method of breaking down carbohydrate food.

Complete step by step answer:
- Stomach: Stomach secretes digestive juices proenzyme pepsinogen and acid. Mucus is secreted by the mucus membrane. acid is secreted by oxyntic cells. Any germs in food acid kill it and make the medium in the stomach acidic. For the working of a gastric enzyme acidic medium is important. Pepsinogen changes to pepsin. It digests protein into peptides. Hence option A is inaccurate.
- Intestine: Digestion of proteins begins within the stomach with the assistance of the enzyme pepsin which breaks down the peptide bonds. The partly digested food or chyme then moves into the little intestine where there are pancreatic enzymes aside from intestinal juices. Hence option B is wrong.
- Oesophagus: The oesophagus is the muscular tube which has two styles of muscles. The upper part of the Osophagus contains muscle. It has voluntary functions like eating, breathing, etc. The lower part contains smooth muscle, with the center part containing a combination of both. Hence C is wrong.
- Mouth: Mouth is the beginning of the gastrointestinal system which plays a crucial role in digestion. By the teeth, food is crushed into small pieces. Then It mixes with saliva and therefore the enzyme amylase (found in saliva), which breaks down starch into sugars. Hence option D is correct.
Hence, option D: the mouth is the correct answer.

Note: Tricky method, Digestion starts in mouth and starch is the biomolecule whose digestion is first administered by the Ptyalin enzyme present in saliva. No digestion occurs in oesophagus. From mouth to stomach it transports semi-solid bolus of food. Intestine comes after the stomach. The stomach is vital for the digestion of proteins.