Pigmented skin is dominant over albino skin. For the following genotypes, determine the phenotypes:
AA:
Aa:
aa:
AA and Aa = pigmented
aa = ablino
Different versions of a gene that produce different versions of traits in offspring.
Alleles
What shape represents a male in a pedigree?
Square
In chickens, BB calls for a black chicken. WW calls for a white chicken. The BW combination calls for the blue Andalusian chicken. Cross a blue hen with a blue rooster.
What is the probability that the offspring are white?
25%
Having dimples is dominant over the absence of dimples. Cross a heterozygous dimpled man with a woman who does not have dimples.
What is the probability that this couple has a child without dimples?
50%
Individuals would need two copies of this allele for it to be expressed.
Recessive alleles
True or False. Shaded individuals are ALWAYS recessive.
False.
In cows, red and white coloration alleles are codominant. A cow that has both alleles will be ROAN (spotted with red & white patches).
RR = red WW = white RW = roan
A roan cow is crossed with a red cow.
What percent of the offspring will be white?
0%
In dogs, the allele for short hair (B) is dominant over the allele for long hair (b). Two short-haired dogs have a litter of puppies. Some of the puppies have short hair, and some have long hair.
What are the genotypes of the parents?
Bb and Bb
Genes that exist in forms with more than two alleles
Multiple Alleles

The above pedigree is tracking a recessive disorder. What must be the genotype of the parents in generation 1?
Heterozygous
A wealthy, elderly couple dies together in an accident. Soon after, a man shows up to claim their fortune, claiming that he is really their only son who ran away from home when he was a boy. Hospital records show that the deceased couple was blood types AB and O. The claimant to the fortune was type O. Was he an imposter? Explain.
Given the following parental genotypes, what alleles could each parent pass to their offspring?
AaBb
AB, Ab, aB, ab
When both alleles contribute to the phenotype and are visible.
Codominance
The pedigree above tracks a dominant trait.
What must be the genotype of individual 2 in generation II?
Homozygous recessive
Hemophilia is an X-linked genetic disorder.
Cross a woman who is a carrier for hemophilia to a hemophiliac man.
What is the probability that they have a child with hemophilia?
50%
Right-handedness (R) is dominant over left-handedness (r). The ability to roll your tongue (T) is dominant over the inability to roll your tongue (t).
What offspring might be expected from a cross involving the following parents: RRTt x RRTt
Right-handed, tongue roller
Right-handed, nonroller
Every individual carries two alleles for each trait. These two alleles separate during gamete formation.
The principle of segregation

What is the likely mode of inheritance for the trait represented in the above pedigree?
X-linked recessive
A woman is searching for her father, and she has type O blood. She looks through records of men who could be her father.
Which blood type can she eliminate from her search? Explain how you know this.
Type AB, an AB individual cannot carry the recessive allele for type O blood.