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In a genetic cross between the genotypes WWXX and wwxx, the following phenotypic distributions were observed among the F2 progeny: WX, 562; wx, 158; Wx, 38; and wX, 42. Likewise, a cross between XXYY and xxyy yielded the following results: XY, 675; xy, 175; Xy, 72; and xY, 78. Similarly, a cross between WWYY and wwyy yielded: WY, 292; wy, 88; Wy, 12; and wY, 8. In all the genotypes, capital letters denote the dominant allele. Assume that the F1 progeny were self-fertilized in all three crosses. Also, double cross-over does not occur in this species. Which of the following is correct?
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- Relative position: W-X-Y Distances: W-X = 5 map units, X-Y = 17 map units
- Relative position: X-Y-W Distances: X-Y = 15 map units, Y-W = 11 map units
- Relative position: Y-W-X Distances: Y-W = 5 map units, W-X = 11 map units
- Relative position: X-W-Y Distances: X-W = 5 map units, W-Y = 10 map units
Correct Option: C
In the various genetic crosses, it can be seen that W and Y are more close to each other than X and Y. At the same time, X and W are close to each other while Y is farthest from X. So, the relative positioning of the genes are Y-W-X and y-w-x.
Now, Relative distances of genes with respect to each other are as follows :
Distance of W gene from Y, Y - W = 5 units and W from X, W - X = 11 units
