11. Using the information from problem 10, scientists do a further testcross usin a heterozygote for height and nose morphology. The offspring are: tall-upturned snount, 40: dwarf-upturnes snout, 9: dwarf-downturned snout, 42; tall-downturned snout, 9. Calculate the recombination frequency from these data; then use your answer from problem 10 to determine the correct sequence of the three linked genes. - Between T and S: 18% -The sequences if genes is T-A-S 12. The ABO blood type locus has been mapped on chromosome 9. A father who has blood type AB and a mother who has blood type O have a child with trisomy 9 and blood type A. Using this information, can you tell in which parent the nondisjunction occurred? Explain your answer. Father: IaIb Mother: i i Ia Ia i Ia i Ib Ib i Ib i -The nondisjunction occurred was inherited form the mother because if it was the father the child would have had AB blood type. 13. Two genes of a flower, one controlling blue (B) versus white (b) petals and the other controlling round (R) versus oval ® stamens, are linked and are 10 map units apart. You cross a homozygous blue-oval plant with a homozygous white-round plant. The resulting F1 progeny are crossed with homozygous white-oval plants, and 1,000 F2 progeny are obtained. How many F2 plants of each of the four phenotypes do you expect? -There are 450 each of blue-oval and white round (parentals) and 50 each of blue-round and white-oval (recombinants) for the F2 plants. 14. You design Drosophila crosses to provide recombination data for gene a, which is located on the same chromosome shown in Figure 15.8. Gene a has recombination frequencies of 14% with the vestigial-wing locus and 26% with the brown-eye locus. Where is a located on the chromosome? -The chromosome is located about 1/3 of the distance from the vestigial-wing locus to the brown-eye locus.