1. In human beings, brown eyes are usually dominant over blue eyes. Suppose a blue-eyed man marries a brown-eyed woman whose father was blue-eyed. What proportion of their children would you predict will have blue eyes?
2. In summer squashes, white fruit color (W) is dominant over yellow (w). If a squash plant homozygous for white is crossed with one homozygous for yellow, A. what will be the appearance of the F1 ? B. of the F2 ? C. of the offspring of a cross of the F1 back to its white parent? D. of the offspring of a cross of the F1 back to its yellow parent?
3. Two black female mice are crossed with the same brown male. In several litters female 1 produced 9 blacks and 7 browns; female 2 produced 17 blacks. What deductions can you make concerning inheritance of black and brown coat color in mice? What are the genotypes of the parents in this case?
4. In Andalusian chickens, the heterozygous condition of the alleles for black feathers (B) and white feathers (B') is gray. Black feathers are produced by BB and white by B'B'. What offspring will a gray Andalusian hen have if bred to roosters with the following feather colors:
(A) black rooster BB x grey hen BB'
(B) gray rooster BB' x grey hen BB'
5. A cross between a white-fruited and a yellow-fruited squash plant produces all white plants. If two of the white offspring are crossed together, what will be the appearance of their offspring?
6. Suppose that two Dd Ee Ff Gg Hh individuals are mated. What is the predicted frequency of dd EE Ff gg Hh offspring from such a mating (do not use a Punnett square).
7. A man and a wife both have normal color vision but a daughter has green color blindness, a sex-linked recessive trait. The man sues his wife for divorce on grounds of infidelity. Can genetics provide evidence supporting his case?
8. In cats, short hair is dominant over long hair; the gene involved is autosomal (not on the sex chromosome). An allele, B1, of another gene, which is sex-linked, produces yellow coat color; the allele B2 produces black coat color; and the heterozygous combination of B1/B2 produces tortoiseshell (calico) coat color. If a long-haired black male is mated with a tortoiseshell female homozygous for short hair, what kind of kittens will be produced in the F1 generation. If the F1 cats are allowed to interbreed freely, what are the chances of obtaining a long-haired yellow male?
9. In Drosophila melanogaster there is a dominant allele for gray body color and a dominant allele of another gene for normal wings. The recessive alleles of these two genes result in black body color and vestigial wings. Flies homozygous for gray body and normal wings were crossed with flies that had black bodies and vestigial wings. The F1 progeny were then test crossed, with the following results:
Are these linked? Defend your answer. If so, how far apart are they (based on these results only).
10.The recombination frequency between linked genes A and B is 40%; between B and C, 20%; between C and D, 10%; between C and A, 20%; between D and B, 10%. What is the sequence of the genes on the chromosome?