Question

Which of the following protein destroys the antigen when it enters in body cell:
(A) Antibodies
(B) Insulin
(C) Chromoprotein
(D) Phosphoprotein

Answer 1

Hint: Check the nature of all the substances given in above options. Also check from where they are released and where they act, this will help you to get an idea of the work they perform. Some of them are hormones and some are enzymes whereas some have altogether different natures.

Complete Step by Step Solution:
Insulin is a hormone released from beta cells of islets of langerhans. It is a peptide hormone. Insulin plays a key role in maintaining glucose level in the blood. It increases permeability of cells for glucose which increases uptake cellular uptake of glucose thus decreasing blood glucose level. This hormone is antagonist to glucagon (glucagon increases blood glucose level), so both of these hormones help in maintaining normal blood glucose level. So, option (B) is incorrect.

A chromoprotein is a protein that contains a prosthetic group (or cofactor). A common example is haemoglobin, which contains haem cofactor. Haemoglobin is the molecule that appears oxygenated blood appear red. So, option (C) is incorrect.
Phosphoproteins are conjugate proteins, modified by attachment of phosphate groups. Common examples of phosphoproteins are milk protein casein and ovo-vitellin of egg yolk. So, option (D) is also incorrect.

Antibody is a glycoprotein, also known as immunoglobulin. It is a large Y shaped protein used by the immune system to identify foreign objects such as bacteria and viruses and also neutralise them. Antibody recognizes a unique molecule of the pathogen called an antigen.
So, option (A) is the right answer

Note: Note that all of the given options are proteinaceous in nature but all of them have different functions to perform. Note that all antibodies are proteins but the vice-versa is not true that all proteins are not antibodies.