In rabbits, black hair depends on a dominant allele, B, and brown hair on a recessive allele, b. Short hair is due to a dominant allele, S, and long hair to a recessive allele, s. If a true-breeding black short-haired male is mated with a brown long-haired female, describe their offspring. What will be the genotypes of the offspring? If two of these F1 rabbits are mated, what phenotypes would you expect among their offspring? In what proportions?

Tim and Jan both have freckles but their son Mike does not. Show with a Punnett square how this is possible. If Tim and Jan have two more children, what is the probability that both will have freckles?

The genotype of F1 individuals in a tetrahybrid cross is AaBbCcDd. Assuming independent assortment of these four genes, what are the probabilities that F2 offspring will have the following genotypes?a. aabbccddb. AaBbCcDdc. AABBCCDDd. AaBBccDde. AaBBCCdd

Both Tim and Jan have a widow's peak (see Module 9.8), but Mike has a straight hairline. What are their genotypes? What is the probability that Tim and Jan's next child will have freckles and a straight hairline?

What is the probability that each of the following pairs of parents will produce the indicated offspring? (Assume independent assortment of all gene pairs.)a. AABBCC×aabbcc→AaBbCcb. AABbCc×AaBbCc→AAbbCCc. AaBbCc×AaBbCc→AaBbCcd. aaBbCC×AABbcc→AaBbCc

In fruit flies, the genes for wing shape and body stripes are linked. In a fly whose genotype is WwSs, W is linked to S, and w is linked to s. Show how this fly can produce gametes containing four different combinations of alleles. Which are parental-type gametes? Which are recombinant gametes? How are the recombinants produced?

SCIENTIFIC THINKING The breakthrough that led Bateson and Punnett to recognize the existence of linked genes was the appearance of unexpected results after they crossed double heterozygous pea plants (PpLl) with each other. Imagine that you have a group of Labrador retrievers that are all heterozygous for both coat color and blindness (BbNn). If you used this group of dogs to produce 160 puppies, how many puppies of each phenotype do you expect to get if the genes are not linked? How would the results differ if the genes are in fact linked?