Genetics problem II
Use your own paper. Remember to define alleles, write down the cross, show Punnett
Square, and give all possible genotypes and phenotypes and their ratios.
In cats, long hair is recessive to short hair. A true-breeding (homozygous) short-haired
male is mated to a long-haired female. What will their kittens look like?
Mrs. And Mr. Smith both have widow’s peaks (dominant). Their first child also has a
widow’s peak, but their second child doesn’t. Mr. Smith accuses Mrs. Smith of being
unfaithful to him. Is he necessarily justified? Why or why not?
A male green parakeet breeds with a female blue parakeet. All the offspring are green.
What trait is dominant?
An apterous (wingless) male stonefly mates with a winged female stonefly. All 200
offspring are winged. After these F1 offspring mature, a male and female are mated.
What proportion of the F2 offspring will be apterous (wingless)?
Yellow is the dominant color for sulfur butterflies, while white is recessive. A
heterozygous sulfur butterfly breeds with a homozygous recessive sulfur butterfly. What
is the pehonotype ratio of the offspring?
In dogs, straight ear is dominant to flop ear. You decide to adopt a stray straight-eared
dog. What possible genotypes might this dog be?
In cats, extra toes is dominant to five toes and long tails are dominant to stub tails. A
heterozygous six-toed, heterozygous long-tailed cat breeds with a five-toed, stub-tailed
cat. What proportion of kittens will have five toes and long tails?
On a certain day in a local hospital, two male babies were born. Shortly after the mothers
returned home with their infants, Mrs. Robinson discovered a tag marked “K” on her baby.
The other mother, Mrs. Koffer, insisted she had her own baby and refused to exchange. The
matter came to court where all concerned agreed to submit to blood test. Here are the results:
Mrs. Robinson – Type O
Mrs. Koffer – Type O
Mr. Robinson – Type O
Mr. Koffer – Type AB
Baby taken home by the Robinsons – Type A
taken home by the Koffers – Type O
Did a switch occur? Explain using Punnett Squares to support your answer.
In goats, a recessive gene causes the goats to "faint" when they are startled. A farmer breeds two
goats (that have never fainted) and their first offspring faints two days after its birth. What must
the parent's genotypes have been? Show the cross to prove it.
In guinea pigs, short hair is dominant to long hair. Also in guinea pigs, black eyes are dominant
to red eyes. A male guinea pig that is heterozygous for both traits is crossed with a female that is
long haired and red eyed. What are the expected phenotypes of their offspring and in what
proportion?
What would be the blood type of the offspring of the following combinations of parents?
a. A type O male with a AB female
b. A homozygous type B male and a heterozygous type A female
In shorthorn cattle, coat color may be red, white or roan. Roan is a mixture of red hairs and white
hairs. The calves produced from the mating of a roan bull and a roan cow might be red, roan or
white. Show the genotypes of parents and predict offspring for each cross.
a. red bull and red cow
b. white bull and red cow
c. red bull and roan cow
In fruit flies, red eyes (XR) are dominant over white eyes (Xr). Draw a Punnett square that shows
the genotype and phenotype ratios of a cross between a white-eyed male and a heterozygous redeyed female.
Hemophilia is caused by a recessive allele on the X chromosome. Using H for normal
clotting and h for non-clotting found in hemophiliacs, draw a Punnett square that shows how
a mother whose blood clots normally can have a daughter with hemophilia.
a. What is the father's genotype and phenotype?
b. Why is it extremely uncommon for a female to have hemophilia?
In guinea pigs, black fur is dominant over white fur.
A heterozygous black male is mated with a white female. Find:
a. genotypes of each parent
b. genotype and phenotypes for F1 generation.
A homozygous male is mated with a white female. Find:
a. genotypes of each parent
b. genotype and phenotype for F1 generation
c. genotype and phenotype for F2 generation
In humans, polydactyl (the presence of extra fingers and toes) is caused by a dominant
allele.
Anne Boelyn had six fingers on one hand. Her husband, King Henry VIII of England, did not
exhibit polydactyl. Their daughter, Queen Elizabeth I, had five fingers on each hand. List the
genotypes of:
a. Anne Boelyn
b. Henry VIII
c. Elizabeth I
Unfortunately for her, Anne’s head was chopped off before she had any other children. List the
genotypes and phenotypes for any other children she and King Henry may have had.
Draw Punnet squares for the indicated crosses and give expected genotypes from each
cross.
1. AABB x aaBb
2. AaBb x Aabb
3. AaBb x AaBb
What are the genotypic and phenotypic distributions for the F1 and F2 generations from a cross
between a red (RR) carnation and a white (rr) carnation if the color is determined by alleles that
show incomplete dominance.
What are the genotypic and phenotypic distributions for the F1 and F2 generations from a cross
between a chick with black (BB) feathers and chicken with white (WW) feathers if the color is
determined by alleles that show codominance. The heterozygote is an erminette chicken, which
is black and white speckled
A man who is heterozygous Type-A Blood marries a woman who is heterozygous Type-B. Give
the following:
a. P genotypes
b. F1 genotypes
Humans are able to detect color because of a dominant gene carried on the X chromosome. The
recessive allele produces red-green color blindness. A man with normal color vision marries a
female who carries a recessive gene, although her vision is normal. Give the following:
a. P genotypes
b. F1 male genotypes and phenotypes
c. F1 female genotypes and phenotypes
In four o'clocks, red flower color (R) is only partially dominant over white (r), the heterozygotes
being pink. What would be the genotypic and phenotypic ratio of the offspring from two pink
parents?