2. These are insoluble in water.

3. Convert fats into fatty acids and glycerol.

Peptidases :

1. These are for hydrolysing proteins, proteoses, peptones and peptides.

2. These are soluble in water.

3. Convert proteins into amino acids.


(b) Amylase, sucrase, maltase and lactase 

Amylase : It hydrolyses starch into maltose, isomaltose and limit dextrin.

Sucrase ; Hydrolyses sucrose into glucose and fructose.

Maltase : Hydrolyses maltose into glucose molecules.

Lactase : Hydrolyses lactose into glucose and galactose.


(c) Passive and active absorption

Passive absorption :It is a physical process in which the absorption is along the concentration gradient. Energy is not used. Absorption is slow. It does not involve carrier molecules. Metabolic inhibitors have no effect.

Active absorption : It is a vital process in which the absorption is done against the concetration gradient. Energy is used up in the process. Absorption is rapid. It involves carrier molecules. Metabolic inhibitors reduce absorption rate.

(d) Essential and non-essential amino acid

Essential amino acids :
These cannot be synthesised inside the body. These must be taken with diet from outside the body. These are eight in number.e.g. isoleucine, leucine, lysine, methionine, valine, threonine, phenylalanine and tryptophan.

Non-essential amino acids :
These can be synthesised inside the body.  These may or may not be present in diet. These are twelve in number. e.g. alanine, arginine, asparagine, asparatic acids, cysteine, glutamic acid, glycine, histidine, proline, serine and tyrosine.

Enzymes for protein digestion or proteolytic enzymes present in gastric juice are :

Proteolytic enzymes present in pancreatic juice.

Proteolytic enzymes present in pancreatic juice.

Balanced diet : A diet that contains the proper proportions of carbohydrates, fats, proteins, vitamins, minerals, and water necessary to maintain good health. A diet containing all the essential food constituents in proper proportions so that the need for calories, minerals, vitamins and other nutrients are met with is called as balanced diet. It varies according to age and the amount of work.

A balanced diet should have following three qualities :

1. It must be rich in various essential nutrients like vitamins, minerals and some amino acids.

2. It should provide just enough raw materials needed for growth and development, repair and replacement of cells, tissues and organs of the body.

3. It should provide the necessary energy required by the body.

Digestion of nucleic acids : Nucleic acids are digested in duodenum and jejunum-ileum.

Digestion in small intestine : The nucleic acids in  are acted upon by nucleases present in the pancreatic juices. The nucleases act on the nucleic acids to give nucleotides which are further broken down into nucleosides. 

Digestion of nucleotides : Nucleotides are digested in jejunum-ileum. The intestinal juice contains nucleotidases and nucleosidases.

The absorption takes place in the following way in different parts of the digestive system - 

i. In mouth : Certain drugs are absorbed into the blood capillaries lining the mucosa of the mouth and the lower side of the tongue. 

ii. In stomach : Absorption of water, simple sugars and alcohol takes place in the stomach.

iii. In Small Intestine : It is the principal organ for the absorption of pnutrients. The digestion is completed here and the final products of digestion such as glucose, fructose, fatty acids, glycerol and amino acids are absorbed through the mucosa into the blood stream and lymph.
 
iv. In Large intestine : Absorption of water, some minerals and drugs takes place in the large intestine. .