Question

Which of the following secretions does not contain enzymes?
A) Bile
B) Pancreatic juice
C) Intestinal juice
D) Saliva

Answer 1

Hint: Enzymes are proteinaceous substances. They are capable of catalyzing biochemical reactions without themselves undergoing any change. They are also called biocatalysts. Enzymes are synthesized by living cells. But many of them retain their catalytic action even when extracted from the cells.

Complete answer:
Bile is the main exocrine secretion of the liver. It is a watery greenish fluid mixture containing bile pigments, bile salts, cholesterol and phospholipids. It helps in the digestion of fats in the small intestine by bringing about their emulsification.

Let us look at other options that are provided.
The exocrine tissue of the pancreas consists of rounded lobules (acini) that secrete an alkaline pancreatic juice. This juice contains sodium bicarbonate, three proenzymes - trypsinogen, chymotrypsin and procarboxypeptidase and a number of enzymes such as pancreatic alpha-amylase, pancreatic lipase, elastase, DNAse and RNAse. This helps in the digestion of all types of foods.

The secretion of intestinal glands is called intestinal juices or succus entericus. They contain many enzymes – amylase, maltase, isomaltase, sucrase, lactase, alpha-dextrinase, enterokinase, nucleotidases, nucleosidases and intestinal lipase. These enzymes act on all types of food.

The salivary glands secrete viscous fluid saliva. It is a mixture of water and electrolytes derived from blood plasma, mucus and serous fluids, and salivary amylase or ptyalin and lysozyme. Salivary amylase is absent in the saliva of domestic herbivores and in carnivores. Pigs have ptyalin in their saliva.

So, the correct answer is option (A) Bile because it does not contain any enzyme.

Note: The biochemical which is acted upon by an enzyme is called the substrate. In case two biochemicals are involved in a reaction, the same are called reactants. The substances produced in the reaction are termed products. The final products are also called end products.