Test: Immunity and AIDS (January 5) - NEET MCQ

Skin and mucous membrane are the physical barriers that provide the first line of defence or the external defence. These barriers prevent the entry of microorganisms into the body. Outer tough layer of the skin, the stratumm corneum prevents the entry of bacteria and viruses. Mucus secreted by mucous membrane traps the microorganisms and immobilises them.

When HIV enters into the body of a person,it moves into macrophages where RNA genome of the virus replicates to form viral DNA with the help of enzyme reverse transcriptase. This viral DNA gets incorporated into cethe host cell's DNA and directs the infected cells to produce more viruses. The macrophages producing viruses, thus act as HIV enters into helper T-cells where it replicates and produces other virus. this is repeated so that the number of helper T-cells decreases in the body of the infected person. Dysentery (Bacillary) plaque and diphtheria are bacterial diseases, Ringworm appears during summer and rainy season. Widal test is used for confirmation of typhoid.

Antibodies are immunoglobulins which are produced in response to antigenic stimulation. Antibodies are produced by B-lymphocytes. Antibodies direct the antibody-mediated immunity

AIDS is caused by HIV. When HIV enters into helper T-cells, it replicates and produces other viruses that kill the helper T-cells. Thus the number of T-cells decrease in the body of the infected person and the person starts suffering from various infections.

Acquired immunity is the type of immunity acquired during life time. Both cell-mediated immunity (mediated by T-cells) and humoral immunity (mediated by B-cells) are responsible for acquired immunity. Acquired immunity is characterised by memory. This means that when our body encounters a pathogen for the first time, it produces a response called primary response which is of low intensity. Active immunity and passive immunity are types of acquired immunity. Polymorphonuclear leucocytes and natural killer cells are involved in innate immunity. These cells phagocytose and destroy microbes.

Reverse transcription takes place during the formation of viral genomic RNA from DNA.

AIDS (Acquired immuno deficiency syndrome) is human immunodeficiency syndrome, a series of diseases caused by the human immunodeficiency virus or HIV. It may also be referred to as HIV disease or HIV infection.

Spleen is a secondary lymphoid organ

Transfer of immune products like antibodies and immunoglobulins to a recipient is called passive immunity. Colostrum, a yellowish milk secreted by mother during the initial days of lactation has abundant antibodies to protect the infant. In tetanus, we need to directly inject the preformed antibodies or antitoxin (a preparation containing antibodies to the toxin). These both are examples of passive immunity.

By mosquitoes, ticks, or other insects. Through saliva, tears, or sweat. By hugging, shaking hands, sharing toilets, sharing dishes, or closed-mouth or “social” kissing with someone who has HIV. Through other sexual activities that don't involve the exchange of body fluids (for example, touching).