Laws of Mendelian Genetics 1

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Laws of Mendelian Genetics 1. Silky feathers in fancy breeds of chickens are caused by a gene whose effect is recessive to that for normal feathers. a. If ninety-six birds were raised from a cross between individuals that were heterozygous for this gene, how many would be expected to be silky and how many would be expected to be normal? b. If you had a normal feathered bird, what would be the easiest way to determine whether it is homozygous or heterozygous? 2. Short hair in rabbits is governed by a dominant gene (L) and long hair by its recessive allele (I). Black hair results from the action of the dominant genotype (B_) and brown hair from the recessive genotype (bb). a. Determine the expected genolypic and phenotypic ratios in progeny from the cross of LLBb x LIbb. b. From the crosses between LIBb x LIBb, i. What is the expected phenotypic ratio among the progenies? ii. What percentage of the F, progenies breed true? ili. What percentage of the F, genotypes is heterozygous for only one pair of genes? iv. What percentage of the F, genotypes is heterozygous at both loci? V. What percentage of the F, genotypes could be used for testcross purposes? vi. What percentage of all short haired F, individuals is expected to be brown? vil. What percentage of all black F, individuals will true for both black and short hair?