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Unformatted text preview: 59) The fitness of the W/S genotype indicates that: a) It is replacing itself and therefore selectively neutral b) It is increasing in frequency in the genotype pool c) It codes for the second best gene transport machine d) It will eventually predominate in the genotype pool e) None of these answers is correct ________________________________________________________________________________________ 60) Which statement summarizes the process of evolution by natural selection: a) Those phenotypes that code for genotypes that transport more gene copies from generation to generation will eventually predominate within a population. b) Those genotypes that code for phenotypes that transport more genome copies from generation to generation will eventually predominate within a population. c) Genes accumulate in the gene pool because they code for phenotypes that have the highest survival. d) Genotypes accumulate in the gene pool because they code for phenotypes that have the highest survival. e) None of these answers is correct 61) The mechanism by which the AZT drug helps to protects against HIV: a) It prevents the HIV virus from entering a CD4 + helper T-cell. b) It makes the Δ CCR5 allele better at preventing the HIV virus from entering a CD4 + helper T-cell. c) It directly blocks reverse transcription of the HIV viral genome. d) It directly blocks transcription of the DNA copy of the HIV viral genome. e) Both answers b & d are correct. 62) AZT is effective initially, but not after a few years, because: a) HIV evolves to increase its mutation rate b) HIV evolves to increase the selectivity of its reverse transcriptase to alternative nucleotides (T vs. Z) c) HIV evolves to decrease its generation time (less time per generation) d) In general, HIV evolves rapidly due to high mutation rate, large population size, and short generation time e) Both answers b & d are correct 63) HIV infection leads to AIDS when: a) Reverse transcription evolves to be so fast that it overwhelms the immune system b) The immune system becomes fatigued from many years of battling HIV c) The density of CD4 + helper-T cells drops to sufficiently low levels d) The HIV virus has had an average of about ten years to evolve e) Both answers c & d is correct 64) Which of the factors listed below would NOT decrease the probability of an influenza pandemic: a) Immunize farm animals so that they are infected with the influenza virus less frequently b) Reduce contact between farm animals and wild birds c) Reduce contact between people and farm animals d) Immunize wild birds so that they are infected with the influenza virus less frequently e) None of these answers is correct 65) Based on your knowledge of the way AZT protects against the HIV virus, which statement is true concerning a new anti-HIV drug that is a base analog of the Guanine DNA nucleotide ....
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- Winter '07
- hiv virus, CD4+ Helper