C) Kaposi\'s sarcoma, which causes a skin cancer in people with AIDS but rarely
ID: 133987 • Letter: C
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C) Kaposi's sarcoma, which causes a skin cancer in people with AIDS but rarely in those not infected by HIV D) the virus that causes a form of the common cold, which recurs in patients many times in their lives 93. Yearly vaccination of humans for influenza viruses is necessary because A) of an increase in immunodeficiency diseases C) surviving the flu one year exhausts the immune system to nonresponsiveness the second year D) rapid mutation in flu viruses alters the surface proteins in infected host cells B) the flu can generate anaphylactic shock 94. Which of the following components of the immune system destroys bacteria by punching holes in the wall of the bacteria? A) complement protein B) macrophages C) plasma cells D) major histocompatibility complex proteins 95. Which of the following components of the immune system destroys cancerous cells by punching holes in plasma membranes and triggering apoptosis? A) toll-like proteins B) macrophages D) cytotoxic T cells C) plasma cells 96. For the successful development of a vaccine to be used A) the surface antigens of the pathogen stay the same B) all of the surface antigens on the pathogen be identified C) the pathogen has only one epitope D) the major histocompatibility (MHC) molecules are heterozy gous 97. Naturally acquired passive immunity can result from the B) ingestion of interferon D) absorption of pathogens through mucous membranes A) injection of vaccine C) placental transfer of antibodies 98. When antibodies bind antigens, the clumping of antigens results from A) the antibody having at least two binding regions C) bonds between class I and class II MHC molecules B) disulfide bridges between the antigens D) denaturation of the antibodies 09 What major advantage is conveyed by having a system of adaptive immunity? A) It enables a rapid defense against an antigen that has been previously encountered instantly the first time they are encountered ) It results in effector cells with specificity for a large number of antigens D) It allows for the destruction of antibodies Within a differentiated B cell. the rearrangement of DNA sequences between variable regions and joining 100. regions is accomplished by a(n) C) A) RNA polymerase B) reverse transcriptase D) recombinaseExplanation / Answer
93. Option D. rapid mutation in flu viruses alters the surface proteins in infected host cells
Explanation: Vaccination works by inducing production of antibodies in the body by introduction of attenuated antigens. Flu viruses rapidly mutate to produce altered surface proteins with which the antibodies already produced by previous vaccinations cannot work. Hence, yearly vaccination is required.
94. Option A. Complement protein
Explanation: Macrophages detect and kill invading pathogens by secreting cytokines and promote innate or adaptive immunity. They control inflammation and contribute directly to the repair of damaged tissues by removing dead cells. Plasma cells are terminally differentiated B cells which are short lived and mostly are antibodies. Major Histocompatibility proteins are expressed on the surface of nucleated cells which bind and present antigens to T cells. Complement proteins punch holes in the bacterial cell membrane, hence the answer is option A
95. Option D. Cytotoxic T cells
Explanation: Plasma cells, macrophages are explained before, Toll like receptor proteins are involved in first line of defence by pattern recognition, pathogen associated molecular patterns. Cytotoxic T cells (Natural killer cells) kill the virus infected or cancerous cells by punching holes in plasma membrane.
96. Option A. the surface antigens of the pathogen stay the same
Explanation: Vaccination works by invoking the production of antibodies and provides protection when surface antigens remains the same. All of the surface antigens need not be identified to develop vaccines, and pathogens have more than one epitope. It also does not depende upon heterozygosity of major histocompatibility complex. Hence, option A is the correct answer.
97. Option C. placental transfer of antibodies
Explanation: Injection of vaccine provides artificial active immunity, absorption of pathogens through mucous membranes provides natural active immunity. Interferons are involved in both active and passive immunity. Transfer of antibodies through placenta produces passive immunity in the newborn as there is no production of antibodies in the baby, it can be called as passive immunity and since the origin is natural source, it is natural acquired passive immunity.
98. Option A. the antibody having at least two binding regions
Explanation: Antibodies have two antigen binding sites (Fab) with which it binds to the antigen. Disulfide bridges are present on the Fab hinge regions, denaturation of antibodies will result in loss of activity while MHC molecules are not responsible in clumping. Hence, the correct answer is option A.
99. Option A. It enables a rapid defense against an antigen that has been previously encountered
Explanation: Adaptive immunity do not enable to counter pathogen for the first time but for the second exposure as there is production of antibodies, effector cells (antibodies) are specific to single antigen, and there is production of antibodies but not their destruction. Hence, the correct answer is option A.
100. Option D. recombinase
Explanation: RNA polymerase uses a single strand of the double stranded DNA as a template to make an RNA polymer that is complimentary in sequence. Reverse transcriptase is used for synthesis of double stranded DNA from single stranded RNA and degradation of RNA strand. Telomerases protect chromosomes from degradation and end to end fusion. Recombinase is responsible for rearragement of DNA sequences between variable regions and joining regions.
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