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Q3: There is 42% crossing over between the locus of p and that of c in the rat. Suppose that 150 primary oocytes could be scored for chiasmata within this region of the chromosome. How many of these oocytes would be expected to have a chiasma between these two genes? Q4: Two recessive genes in Drosophila (b and vg) produce black body and vestigial wings, respectively. When wild-type flies are testcrossed, the F1 are all dihybrid in coupling phase. Testcrossing the female F1 produced 1930 wild type 1888 black and vestigial : 412 black : 370 vestigial. (a) Calculate the distance between b and vg. (b) Another recessive gene cn lies between the loci of b and vg, producing cinnabar eye color. When wild-type flies are testcrossed, the F1 are all trihybrid. Testcrossing the F1 females produced 664 wild type : 652 black, cinnabar, vestigial: 72 black, cinnabar: 68 vestigial: 70 black: 61 cinnabar, vestigial: 4 black, vestigial: 8 cinnabar. Calculate the map distances. (c) Do the b-vg distances calculated in parts (a) and (b) coincide? Explain. (d) What is the coefficient of coincidence? Levit Chemical nature of pdf A