Question

How many sentences is/are true among the following sentences?
i) Allergy is due to release of histamine and serotonin from mast cells.
ii) Cell mediated immunity is responsible for rejection of graft.
iii) Principles of vaccination are based on the diversity of the immune system.
iv) Both bone marrow and thymus provide a micro environment for development and maturation of T-lymphocytes.

(A) One
(B) Two
(C) Three
(D) Four

Answer 1

Hint: Immunity is defined as the ability of multicellular life forms to oppose destructive microorganisms. Resistance can be characterized as a complex organic framework enriched with the ability to perceive and endure whatever has a place with oneself and to perceive and dismiss what is unfamiliar (non-self). The immunity is present by birth or can be acquired as an adult.

Complete answer:
Now, let’s have a look at the above choices one by one.
> Allergy is when the body reacts to the entry of a foreign substance into it which is potentially harmless. The mast cells produce histamine to counter the foreign substance. However, expanded measures of serotonin, just as histamine, have been found in the blood of creatures during shock. But, serotonin is not produced during allergy. Hence, this statement is incorrect.

> Transplant rejection is caused by a cell-mediated immune response and affects the HLA antigens present on donor antigen-presenting cells (APCs). Recognition of donor’s antigens on the cells of the graft performed induces vigorous T cell division in the recipient. Hence, statement B is correct.

> The ultimate aim of vaccination is to provide immunity against infections as different infections are caused by different microbes. It focuses on being proactive by conferring immunity to the host before it affects them. Hence, this option is incorrect.

> Both bone marrow and thymus provide a microenvironment for the development and maturation of T-lymphocytes as T cells are first formed in the Bone marrow and then they undergo further formation in the Thymus. So, both bone marrow and thymus are involved.

Hence, the correct answer is option (B). Here (ii) Cell mediated immunity is responsible for rejection of graft and (iv) Both bone marrow and thymus provides a micro environment for development and maturation of T-lymphocytes are right options.

Note: Points to remember-
> Serotonin granules are found to be stored in some mast cells but there is no proper information about their secretion.
> Vaccines are made from either dead microbes or live microbes (attenuated). This mimics the actual pathogen which has less morbidity, thus helping the body to develop immunity against it.