Digestion is completed in
(a) Duodenum
(b) Ileum
(c) Stomach
(d) Cloaca

Hint: Digestion is the process by which complex food substances are broken down into small simple absorbable forms. These simple molecules are then broken down in our cells to release energy which is trapped in the form of ATP.

Complete Step by Step Answer:
Digestion is completed in the ileum region of the small intestine. The last digestive enzymes are released in the small intestine hence digestion is completed here only because no digestion can occur without the help of enzymes catalyzing the reaction. The last enzymes released in the small intestine come from the pancreatic juice and intestinal juice. No enzymes are released in the large intestine, as mostly absorption of water and drugs takes place in it.

Therefore, the correct option is ‘Ileum’.

Additional information:
Let us study the digestion process in the small intestine.
- Proteins, peptones, and proteoses are converted into dipeptides by trypsin and chymotrypsin. These dipeptides are converted into amino acids by dipeptidases.
- Polysaccharides (starch) are converted into disaccharides by amylase which is then converted into glucose with the help of maltase, lactase, etc.
- Fats are converted into triglycerides by lipases which are further broken down to monoglycerides. These monoglycerides are then finally broken down to fatty acids and glycerol by lipases.
- Nucleic acids are broken down into nucleotides by nucleases. Nucleotides are broken into nucleosides by nucleotidases. Nucleosides are broken into sugars and bases by nucleosidases.

Note:
- Most of the digestion takes place in the duodenum itself and mostly simple substances are absorbed in the jejunum.
- The undigested and unabsorbed substances coming from the large intestine are known as feces that are stored temporarily in the rectum.
- Bile juice does not contain any enzymes, only salts that help in the emulsification of fats.