Question

what is b and c?

1) In marsh lizards rough scale (st) is completely dominant to smooth scale (s). Eye colour is determined by an incompletely dominant sex-linked allele and can be blue (b+), or yellow (b) with the heterozygote giving green eyes. A further gene (t) controls tail formation giving rise to a bent tail in homozygotes, t allele is dominant with respect to straight tail formation but is a recessive lethal. Parental genotypes of following phenotypes: A smooth, blue eye, straight tail male lizardssXh+Ytt was crossed with a smooth, green eyed, straight tail female lizard; $$XXtt b) What will be the appearance and proportion of the offspring? (draw a branch diagram to illustrate the expected segregation) c) For a cross between a normal tail, green eye female and a crooked tail yellow eyed male, both heterozygous at the scale locus. What is the probability of obtaining a rough, yellow eye, crooked tail female in the next generation?

Answer 1

for performing a treehybrid cross, we can it into 3 monohybrid crosses - ssxss ; xsty x xbxb and tttttt Now we multiply the product of all these separate crosses in a stepwise manner to get the final sumber of offsprings, their genotype and phenolyfe.

bt b) ss X Ytt 6) x ss Xoxo tt ti X ss x SS X bt bt î bk -p-p4-15 ? y xb y uso ttt x Ett - v Neglected since all gindividuals Itt t Chethal) will die. X Ss y bt ss X 2 tt x ssyblys x ssabty s (Proportions) bt bt #t(smath, blues 1 (smooth, blue, bent) 2 oss X X t t (smooth, blue, Issy let ytt bt bttt 2 ss x x y smooth, and straight ) is abtytt. u (smooth, blece, streaight) 4 (smooth, grees, bent) I ssabtytt 4 (smooth, blue, bent 1 ss Xoytt (smoth, yellow, bent) Smooth, yellow, straight)

StS x ot yb tht x ss xy tt sts x sts bt bb x x x X Y + 5x Neglected since we need I only yellow eye.. x 1bb 1 ty Sobet SX xb 1 Neglected since only T 1 jxbly x y k Neglected since only fernale 4 is reequired Rough type required required tttttt J Heglected + + + het at bb les x 16 14 X Toe Neglected creased since we need only 1 EE Crooked tail. 2 th x 2 sto x hyb ut l ri offspring 1 - 4 stst xx t Istot xbxb EL 2 = 3 rough scale, yellow eyed, a ots xbxh tt J 69 crooked tail female 64 Answer