by T – lymphocytes b) Antibodies are protein molecules each of which has four light chains c) Rejection of a kidney graft is the function of B – lymphocytes d) Preformed antibodies need to be injected to treat the bite by a viper snake. . Which one of the following is not a property of cancerous cells whereas the remaining three are? [AIPMT PRE ] a) They compete with normal cells for vital nutrients b) They do not remain confined in the area of formation c) They divide in an uncontrolled manner d) They show contact inhibition .
At which stager HIV infection does one usually show symptoms of AIDS? [AIPMT ] a) Within days of sexual contact with an infected person b) When the infected retro virus enters host cells c) When HIV damages large number of helper T- Lymphocytes d) When the viral DNA is produced by reverse transcriptase . Match each disease with its correct type of vaccine [AIPMT ] XII Std Biology-Zoology Competitive Questions XII Std Biology-Zoology Competitive Questions MCQs for Higher Studies a)Tuberculosis i) harmless virus b)Whooping cough ii) inactivated toxin c)Diphtheria iii) killed bacteria d)Polio iv) harmless bacteria a) b) c) d) a) (ii) (i) (iii) (iv) b) (iii) (ii) (iv) (i) c) (iv) (iii) (ii) (i) d) (i) (ii) (iv) (iii) . Which of the following is correct regarding AIDS causative agent HIV?
[NEET-II, ] a) HIV is enveloped virus that contains two identical molecules of single-stranded RNA and two molecules of reverse transcriptase b) HIV is unenveloped retrovirus c) HIV does not escape but attacks the acquired immune response d HIV is enveloped virus containing one molecule of single – stranded RNA and one molecule of reverse transcriptase Chapter - Microbes in Human Welfare . When domestic sewage mixes with river water [AIPMT MAINS ] a) Small animals like rat will die after drinking river water b) The increased microbial activity releases micronutrients such as iron. c) The increased microbial activity uses up dissolved oxygen d) The river water is still