Question

Digestion starts from_____ and ends at ______
(A)Mouth, Small intestine
(B)Mouth, Large intestine
(C)Mouth, Anus
(D)Mouth, Rectum

Answer 1

Hint: Digestion is the process of breakdown of large insoluble food molecules into the smaller water soluble food molecules. It is a type of catabolism which is divided into two processes called mechanical and chemical digestion.

Complete answer:
In mechanical digestion, there is a physical breakdown of large pieces of food into smaller ones which are then accessed by digestive enzymes. In chemical digestion, food breaks down into small molecules the body can use.
1.In the human digestive system food enters the mouth where mechanical digestion occurs by mastication means chewing and wetting contact of saliva.
2.Saliva is a liquid secreted by salivary glands which contains an enzyme called salivary amylase and it starts the digestion of starch present in food.
3.Saliva contains mucus which lubricates the food and hydrogen carbonate which provides the ideal conditions such as alkaline pH for the amylase.
4.Food bolus then enters the stomach where it gets converted into a semi-fluid mass called chyme by acids present.
5.After this food enters the small intestine where it gets digested by other enzymes from pancreas called pancreatic amylase, lipase and trypsin and those obtained from small intestine like maltase.
6.Large intestine absorbs only water from wastes creating stools which then pass from rectus to anus.

Hence the correct answer is option(A)

Note: Due to action of enzymes and due to nutrient absorption most of the digestion takes place in the small intestine. The three main parts of the Small intestine are duodenum, jejunum and ileum.