Name:______Period:______Date:______

Genetics Quiz

  1. In humans there is a disease called Phenylketonuria (PKU), caused by a recessive allele that doesn’t code for the enzyme that breaks down the amino acid phenylalanine. This disease can result in mental retardation or death. Let “E” represent the normal enzyme. Also in humans in a condition called galactose intolerance or galactosemia, which is also caused by a recessive allele. Let “G” represent the normal allele for galactose digestion. In both diseases, normal dominates over recessive. If two adults were heterozygous for both traits (EeGg) set up the Punnett Square:

What are the chances of having a child that:

  • is completely normal? ______
  • has only the disease PKU? ______
  • has only the disease galactosemia? ______
  • has both diseases? ______
  1. In humans straight hair (SS) and curly hair (CC) show incomplete dominance that results in hybrids with wavy hair (CS). Cross a curly hair female with a wavy haired male. Complete a Punnett square for this cross.
  • What are the chances of having a curly haired child?______
  • What genotype(s) produce a curly haired child? ______
  1. Assume that blood type is inherited as A and B dominant over O, but A and B incompletely dominate over each other. Genotypes AA and AO are then phenotypically type A, genotypes BB and BO are type B, genotype AB is type AB, and genotype OO is type O blood.

In the 1950’s a young woman sued film star/director Charlie Chaplin for parental support of her illegitimate child. Charlie Chaplin’s blood type was already on record as type AB. The mother of the child had type A (AO) and her son had type O blood (OO). Complete a Punnett square for the possible cross of Charlie and the mother.

  • The judge ruled in favor of the mother and ordered Charlie Chaplin to pay child support costs of the child. Was the judge correct in his decision based on blood typing evidence? Explain why or why not.
  1. Can a colorblind female have a son that has normal vision? Color blindness is caused by a sex-linked recessive allele. Do the Punnettsquare. *use N = normal vision and n = color blind
  1. Muscular dystrophy is a sex-linked trait. What parental genotypes could produce a female with muscular dystrophy? Do the Punnettsquare.*use M = normal muscles, and m = muscles missing dystrophin protein
  1. Label the genotype for each of the individuals on the below numbered pedigree chart (note: eye color is not a sex-linked trait).

  1. Use the below pedigree chart to answer the following three questions. Muscle type is not a sex-linked characteristic. Shaded individuals express slow twitch muscles.

  • What is the genotype of individual # 3 and 4? Explain your answer.
  • Can either individual # 8 or 9 be homozygous? Explain why or why not.
  • Explain the family relationship that #12 has with #2.
  1. The genotype of F1 individuals in a trihybrid cross is AaBbCC. Assuming independent assortment of these four genes, what are the probabilities that true-bred F2 offspring would have the following genotypes?
  2. aabbcc
  3. AaBbCc
  4. AABBCC