Free Human Health And Diseases (Daily Quiz: 3) NEET Biology Questions & Answers with Detailed Explanation & Full Review

Answer: (c)

IgG is the most abundant class of immunoglobulins in the human body. IgA, IgM, IgE, IgG, etc., are some of the different types of structurally related proteins (immunoglobulins) that act as antibodies.

Answer: (c)

The AIDS retrovirus, called human immunodeficiency virus (HIV), mounts a direct attack on $CD_{4} ^{+}$ T helper cells because it recognizes the $CD_4$ coreceptors associated with these cells.

HIV attack on $CD_{4} ^{+}$ T cells cripples the immune system in at least three ways. First, HIV-infected cells die only after releasing replicated viruses that infect other $CD_{4} ^{+}$ T cells, until the entire population of $CD_{4} ^{+}$ T cell is destroyed. Second, HIV causes infected $CD_{4} ^{+}$ T cells, to secrete a soluble suppressing factor that blocks other T cells from responding to the HIV antigen. Finally, HIV may block transcription of MHC genes, hindering the recognition and destruction of infected $CD_{4} ^{+}$ T cells, and thus protecting those cells from any remaining vestiges of the immune system. The combined effect of these responses to HIV infection is to wipe out the human immune defense.

Answer: (a)

Heroin (smack ) is chemically diacetylmorphine which is white, odourless, bitter crystalline compound. It is obtained by acetylation of morphine, extracted from latex of poppy plant.

Answer: (d)

Belladonna is a drug prepared from the dried leaves and root of deadly nightshade poisonous plant, Atropa belladonna, containing atropine and related alkaloids.