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Material Type: Exam; Class: Microbial Physiology; Subject: Biology / Biological Sciences; University: SUNY at Albany; Term: Forever 1989;
Typology: Exams
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1. The hsr-omega gene is induced by heat stress and is part of the conserved heat-shock response system of Drosophila melanogaster****. Previous studies found two alleles, hsr-omegaa^ and hsr- omegab , in the population. A more extensive survey of several D. melanogaster populations along Australian eastern seaboard yielded a result shown on the right. Which of the following statements is correct? (A) There are more hsr-omrgaa^ allele in northern Australia. (B) This pattern suggests that that the hsr-omegaa allele is adapted to a hot environment. (C) This is an example of a cline. (D) All of the above are correct. (E) None of the above is correct. 2. Which of the following statements about HIV is correct? (A) HIV is a virus containing RNA genomes. But it also uses DNA for part of its life cycle. (B) One of the factors contributing to HIV's success in developing resistance against anti-HIV drugs is because of the high mutation rate resulting from the error-prone viral reverse transcriptase. (C) One of the factors contributing to HIV's success in developing resistance against anti-HIV drugs is because of natural selection sorting through many variants existing in the HIV populations. (D) All of the above (E) None of the above **On the right are several phylogenetic trees. Please question 3 and 4.
5. Streptomycin is an antibiotic that belongs to the class of aminoglycosides. By binding to the 30 S subunit of the bacterial ribosomes, the bound streptomycin molecule causes the misreading of mRNAs, consequently increasing the error rate in protein synthesis. As more incorrect amino acids are incorporated into the proteins, the bacteria die as a result. Before the wide spread usage of streptomycin, most bacterial strains are sensitive to streptomycin. But now, many strains are resistant to it. It is found that several mutations at the rpsL gene, which encodes the S1 2 protein of the ribosome, can confer resistance to streptomycin. Based on the above information, which of the following statements is correct? (A) The emergence of streptomycin-resistant bacterial strains is an example of evolution by mutation. (B) The emergence of streptomycin-resistant bacterial strains is an example of natural selection. (C) Since accurate reading of mRNAs is always better than inaccurate reading, therefore, the increased accuracy would be selected for whether there is streptomycin in the environment or not. (D) All of the above (E) None of the above 6. For any given HIV population, there usually exist mutants that are resistant to various anti-HIV drugs. Assuming that in general 1 in 10 , 000 viruses would be found carrying a mutation resistant to any of the anti-HIV drugs. Let's further assume that at any given time, there are about a total of 1011 viruses circulating in the blood stream. Which of the following statements is correct? (A) The existence of these mutations is due to natural selection. (B) The minimum number of drugs needed for HAART to work is four. (C) Even though we have many types of anti-HIV drugs available, it is still possible for the evolution of multi-drug resistant HIV strains. (D) All of the above (E) None of the above 7. On the right is a graph depicting the phylogenetic relationship of six flowering species (A to E). On top of the species names are the pollination vectors (birds or bees) used by each species. Given the information, which of the following statements is correct? (A) Species E can be used as an ingroup. (B) It is most likely that the most recent common ancestor of species A to E used bees for pollination. (C) It is most likely that the most recent common ancestor of species A to E used bird for pollination. (D) It is most likely that a shift in vector usage has happened in the lineage leading to the most recent common ancestor of species A to D. (E) None of the above is correct. 8. On the right is a graph showing the relationship between A 1 allele frequency and time. Assuming there are only two alleles, A 1 and A 2 in the population, and this is a diploid organism. Which of the following scenarios is a likely explanation for the observed pattern? (A) Selection for the A 1 A 2 genotype (B) Positive frequency-dependent selection (C) Selection against the A 2 A 2 genotype (D) All of the above (E) None of the above
14. High-crowned teeth (teeth that extend high above the gumline) are found in some rodents, rabbits, Artiodactyl (e.g., hippos and pigs), Perissodatyl (e.g., horses), and elephants. Based on the phylogeny shown on the right, which of the following statements is correct? (A) The high-crowned teeth is a shared and derived character. (B) The high-crowned teeth is the result of convergent evolution. (C) The simplest explanation for why lemurs do not have high-crowned teeth is because the trait high-crowned teeth is lost during the evolution of the lemurs lineage. (D) No conclusion can be drawn from the shown phylogeny. (E) None of the above is correct. 15. Which of the following statements about the transmission rate hypothesis is correct? (A) This hypothesis assumes that the probability of a pathogen being transmitted from one host to another depends on how it is being transmitted. (B) According to this hypothesis, sexually transmitted diseases should evolve toward high virulence so as to ensure the transmission of the pathogen to the next host. (C) This hypothesis predicts that a pathogen would evolve toward a low virulence if its main route of spread is through health care providers like doctors and nurses. (D) All of the above (E) None of the above **Tay-Sachs is a neurodegenerative disease that kills its victims before age 5. The disease is due to a recessive allele at a locus on chromosome 15 that encodes for hexosaminidase A. The allele frequency for this disease is estimated to be 0. 1 %. Please answer Questions 16 and 17.
, where! is the mutation rate and s is the selection coefficient.) (A) 10 -^2 (B) 10 -^4 (C) 10 -^6 (D) 10 -^8 (E) None of the above
**Your research project involves in an enzyme called terminal transferase (TR). You found that there are two TR genes, TR 1 and TR 2 , in both the human (H) and mouse (M) genomes, but only one in the fruit fly (D) genome. You sequenced part of these genes and also determined the phylogenetic relationship among these genes, which is shown on the right. The partial gene sequences look like the following: TR 1 (H) TTGGGAATT TR 2 (H) TT---AATA TR 1 (M) TTGGTAATT TR 2 (M) TT---AATC TR(D) TTCGCAATT The three dash lines represent deletions. Please answer question 18 , 19 , and 20.