Honors Biology Genetics Packet
Due: ______________
Mrs. Jackson – 2015-2016
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. Rose comb is dominant to single comb in chickens.
a. What type of offspring would result from the cross between two chickens heterozygous for
these traits?
b. Homozygous for each of these two traits?
2. 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?
3. 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.
4. In humans, polydactyly (an extra finger on each hand) is due to a dominant factor. When one parent
is polydactylous, but heterozygous, and the other parent is normal, what could their children be like?
5. In dogs, wire hair is due to a dominant factor, smooth hair to its recessive allele. Two wire-haired
dogs produce a male pup which is wire-haired. To find out most quickly whether he carries the factor
for smooth hair, he should be mated to what kind of female? Use a Punnett square to support your
answer (should have 2 squares).
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. Right-handedness is dominant. A right-handed man marries a right-handed woman. They have two
children, a son who is left handed and a daughter who is left handed. By a later marriage with another
right-handed woman, this man has 9 children, all of whom are right handed. Draw a pedigree for this
family. Give genotypes for all. Darken the dominant trait.
3. Complete the following pedigree. Add generation numbers, people numbers, genotypes, and make a
key.
4. Complete the following pedigree. Add generation numbers, people numbers, genotypes, and make a
key.
Incomplete/Co-dominance
1. After crossing a red-flowered and a white-flowered four-o’clock, the hybrids are bred haphazardly for
many generations. Finally, you select for propagation 2 pink-flowered specimens and cross them.
What will be the result?
2. 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.
3. Yellow guinea pigs crossed with white ones always produce cream-colored offspring.
a. Cross a white guinea pig and a yellow guinea pig.
b. Cross a cream-colored guinea pig with a white guinea pig.
4. 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. If you were to
start with a roan bull and white cows, could you eventually establish a true-breeding red herd? How?
Show the crosses (and ratios) to support your answer.
5. In andalusian chickens, gray is a blend of pure black with pure white. Cross a gray rooster with a gray
hen. Give the genotypes and phenotypes of their offspring.
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. In canaries, the green variety with black eyes is dependent upon a dominant sex-linked factor (B), the
cinnamon variety with red eyes is due to its recessive allele (b). A cinnamon male is mated to a
homozygous green female. What would be the appearance of the F1 generation? The F2 generation?
2. How is it possible for a father who has a rare abnormality to pass it on to all of his sons, but none of
his daughters? Use a Punnett Square to support your answer.
3. A white-eyed female fruit fly and red-eyed male are crossed. Give the genotype and phenotype ratios
for their possible offspring. (White eyes are X-linked, recessive)
4. 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.