12-2 Biology Genetics Assignment #2

1. In humans blood type is controlled by three alleles A, B and O. A and B are codominant and both are dominant to O. If a man with blood type B, one of whose parents had blood type O, mates with a woman with blood type AB, what will be the percentage of their children having blood type B?

2. Both Mrs. Smith and Mrs. Jones had babies in the same hospital on the same day. Mrs. Smith took home a baby girl she named Shirley. Mrs. Jones took home a baby girl she named Jane. Mrs. Jones soon began to suspect that her baby had been switched with that of Mrs. Smith in the nursery. Blood test results showed the following: Mr. Smith’s blood type is A, Mrs. Smith’s blood type is B. Mr. Jones’ blood type is A and Mrs. Jones’ blood type is A. Shirley’s blood type is O and Jane’s Blood type is B. Did a mix up occur?

3. Coat colour in Labrador retrievers is controlled by three alleles that code for yellow, black or chocolate. The black allele is dominant over chocolate and yellow. The chocolate allele is dominant over yellow. Suppose a black male, whose mother was yellow, was mated with a chocolate female who had a yellow father. What genotypic and phenotypic ratios (label the phenotype ratios) would you find in the offspring?

4. Certain kinds of cattle have two alleles for coat colour that show codominance. If a cow if heterozygous they have a roan coat- spots of red and white, two copies of the red allele results in an all red cow, two copies of the white allele results in an all white cow. A second trait, the absence of horns is dominant to the presence of horns. a. If a bull and a cow both have a heterozygous genotype for both traits, list the different phenotypes could you see in their offspring? b. What is the probability of each phenotype?

5. Certain flowers show incomplete dominance in the colour of their flowers. Red is the dominant colour, white is recessive, but if a plant is heterozygous for flower colour the flower will be pink. If a red flowered plant is crossed with a white flowered plant what is the genotype and phenotype of the F1 generation? If two F1 plants are crossed what are the results in the F2 generation? Give the phenotype ratio.

6. In rabbits 4 alleles control coat colour. The dominant colour is brown (C), it is dominant to chinchilla (c ch), Himalayan (ch ) and albino (c). Chinchilla is dominant to Himalayan and albino. Himalayan is dominant to albino. Determine the phenotypes of the following parents and the possible genotypes and phenotypes (how many of each?) of their offspring. a. Ccch x chc b. cchc x cchch c. cc x Cch d. chch x cchc