In mice, the Y locus controls coat color, and the Y allele (yellow) is dominant to y (non-yellow). All yellow mice are believed to be heterozygous. A cross of two yellow mice results in a 2:1 ratio of yellow to non-yellow mice, indicating that some mice die early in development. Which of the following is an accurate description of the effect of the Y and y alleles on lethality? the Y allele is a dominant lethal allele the Y allele is a recessive lethal allele the y allele is a recessive lethal allele the y allele is a dominant lethal allele

Assume that a single gene determines coat coloration in cats, with the B allele resulting in orange coloration, and b allele results in black coloration. This gene exists on the X chromosome (recall that cats have XX/XY system of sex determination). My cat Pepper is a female tortoiseshell, and my cat Hobbes is an orange male. (i) What is the probability that Hobbes and Pepper have three kittens, Hopper (male), Pepsi (female), and Hippie (female)? What is the probability that they have three kittens, and that Hopper (male), and Hippie (female) are both orange, and that Pepsi (female) is a tortoiseshell? (ii) Distribution of % of Barr Bodies in each body part 120 100 100 80 100 60 40 50 50 20 Head Body Tail Black Orange

You cross true breeding blue and red morning glories and get all blue offspring. a) Based on this information alone: i) How many loci are involved in the expression of this trait? How many alleles? What are the dominant and recessive interactions between the alleles at the locus/loci? ii)what are the possible genotypes of the parents and F1s? iii) Based on your hypothesized genotypes from ii, what do you expect the outcome of a cross between the F1's to be? (i.e. what phenotypes in what ratios?)     b) You then cross the F1 individuals and you obtain the following results Blue - 200 purple - 126 red - 24 i) Are these results statistically consistent with your hypothesis above? (prove it!) ii) If not, what is an alternative hypothesis that might explain these results? Are these results the result of one locus or 2? Test your new hypothesis using chi-squared test. Discuss the meaning of your results. (Note: If your hypothesis proves wrong, that is OK!!! But you have to be able to discuss…

Within a mouse population, the black fur allele (B) is dominant to the white fur allele (b) and the short whisker allele (S) is dominant to the long-whisker allele (s). A heterozygous black-furred short-whiskered mouse is crossed with a homozygous white-furred long-whiskered mouse. What percentage of the offspring will be black-furred with long whiskers?