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Version B noteto D. the two genes are sex linked 1 1. Use the following map of four genes on a chromosome to answer the question (numbers show the recombination frequency). When collecting data from genetic crosses which gene pair is most likely to show the highest frequency of recombination? 5 W 3 E 12 A. A and W B. E and G C. A and E D. A and G 12. Down syndrome is caused by trisomy of the 21st chromosome. Two phenotypically normal parents have a child with Down syndrome. Which statement best characterizes the cause of this condition? A. The mother is a carrier of the Down syndrome allele. B. The mother and father carry the Down syndrome allele. C. One of the gametes produced by one of the parents underwent nondisjunction during meiosis. D. One of the gametes produced by one of the parents underwent a chromosomal duplication during meiosis. 13. Which of the following statements accurately characterizes one of Chargaff's rules? A. The proportion of DNA composed of adenine and is equal to that of thymine. B. The proportion of DNA composed of adenine is equal to that of cytosine. C. The number of chromosomes differs between species D. The structure of DNA differs between species. 14. A sample of double-stranded DNA contains 30% guanine. Approximately what percent of the nucleotides in this sample will be adenine? A. 30% B. 20% bless10 ,05 C. 40% D. 60% 15. During DNA polymerization, nucleotides are added to which of the following: A. The 5' phosphate of the growing DNA strand B. The 5' phosphate of the template strand C. The 3' OH of the growing DNA strand D. The 3' OH of the template strand 16. In E. coli, a mutation in the dnaB gene prevents the helicase from binding at the origin of replication. Which of the following events would you expect to occur as a result of this mutation? A. Additional proofreading will occur. B. No replication fork will be formed. C. Replication will occur via RNA polymerase alone. D. Replication will require a DNA template from another source. 3