CP Biology Genetics Test Review
Mrs. Tokmajian – 2013-2014
Answer on a separate sheet. Use Punnett squares or pedigrees to show your work. Show ratios for genotype and phenotype when asked. No credit will be given without the work. Do all problems in order.
Monohybrid Crosses
1. In man, normal pigmentation is due to a dominant factor, albinism to its recessive allele. A normal man marries an albino woman. Their first child is an albino. What are the genotypes of these three people? If this couple had more children, what would they probably be like?
2. In fruit flies, normal wings are dominant. Vestigial wings are recessive. What type of offspring would result from a cross involving a homozygous normal winged fruit fly and a vestigial winged fruit fly? Give genotype and phenotype ratios for F1 and F2.
Pedigrees
1. Dimples are dominant. A non-dimpled man (both of whose parents were dimpled) marries a dimpled woman (whose father was dimpled and whose mother was non-dimpled). Their child has dimples. Draw a pedigree for this entire family. Give genotypes for all. Darken the dominant trait.
2. Complete the following pedigree. Add generation numbers, people numbers, genotypes, and make a key.
Incomplete/Co-dominance
1. In mice, tan is a blend of brown and white. Cross a tan male with a brown female. Do the Punnett square and show the genotypes and phenotypes of the offspring.
2. Yellow guinea pigs crossed with white ones always produce cream-colored offspring.
- Cross a white guinea pig and a yellow guinea pig.
- Cross a cream-colored guinea pig with a white guinea pig.
3. In certain cattle, hair colors can be pure red or pure white. When both genes are inherited together, the resulting color is called roan, where red hairs are lightened by some white hairs. Cross a roan bull with a white cow. Give the phenotype and genotype ratios.
Blood Types
1. A man has type A blood and his wife has blood type B. A physician types the blood of their four children and is amazed to find among them one of each of the four blood types. He is not familiar with genetics and calls upon you to explain how such a thing could happen. What would you tell him? Show a Punnett Square to help with your explanation.
2. A woman has type A blood and she marries a man with type B blood. Could they have a child with type O blood? Use a Punnett square to prove your answer.
3. A woman sues a man for the support of her child. She has type A blood, her child type O blood, and the man type AB. Could the man be the father? Use a Punnett Square to help with your explanation.
4. A wealthy, elderly couple die together in an accident. Soon after a man shows up to claim their fortune, contending that he is their only son who ran away from home when he was just a boy. Other relative dispute his claim. Hospital records show that the deceased man and woman were blood types AB and O, respectively. The claimant to the fortune was type O. Do you think that the claimant was an imposter? Explain (show Punnett square as proof).
Sex-linked Traits
1. A man sues his wife for divorce on the grounds of infidelity. Both the man and wife have normal vision, but their daughter is colorblind (a known sex-linked recessive trait). If you were the man’s lawyer, could you use this fact as evidence? If so, how would you explain the case to the jury? Use a Punnett Square to aid your explanation.