Genetics Word Problems

Question 1 Burt is Polydactyl (6 fingers or toes on each limb). This is a dominant trait. His wife Jill and his mother Betsy were born with the normal number of digits. What is the probability that their first child will be born polydactyl? [1 min] 50%

Question 2 Jill from question 1 is an albino, which is recessive. What percentage of Burt and Jill’s children are predicted to be polydactyl albinos if Burt is homozygous dominant? [1 min] 0% will be albino – They will all be Heterozygous (Aa) for the albino allele.

Question 3 What is the P (parent) generation genotypes if members of the F1 generation are all heterozygous, and the F2 generation genotypes are in 1:2:1? [2 min] Homozygous dominant and homozygous recessive

X-linked recessive traits Recessive allele exists on X chromosome Males only need one copy to be affected because they only have one X chromosome Phenotype skips a generation because females act as carriers

Question 4 Rick and Susan want to have a child, but they want to make sure it will never go bald. Neither Rick or Susan are bald. Male pattern baldness is an X- linked recessive trait. What has to be true about Rick and Susan’s family and their potential child in order that there will be no chance of baldness? [1 min] Susan’s father must not be bald or the child is female.

Question 5 A man with blue eyes (bb) and black hair (HH) has children with a brown eyed woman (Bb) with blonde hair (hh). What is the probability of a blue-eyed black haired (bbHhXX) girl? [3 min]

Question 6 A man with brown eyed parents has blue eyes. He marries a woman with brown eyes and has 4 kids. One child has blue eyes and three have brown eyes. Two of these kids have an incestuous relationship and produce kids with one brown eye and one blue eye. What is the genotype of the man’s father? [2 min]

Question 7 Bill has brown eyes (Bb) and unattached earlobes (EE). He marries Henrietta who has green eyes (bb) and unattached earlobes (Ee). What is the probable phenotypic ratio of their offspring? What is the probable genotypic ratio of their offspring? [5 min]

Question 8 Bill’s dog is short (tt) and stout (ss). Henrietta’s dog is tall (Tt) and thin (Ss). What is the probable genotypic and phenotypic ratios of the litter?

Incomplete Dominance Heterozygous shows a blend between homozygous dominant and homozygous recessive. Red (RR) Pink (Rr) White (rr)

Question 9 A red (RR) flower that shows incomplete dominance is bred with a pink (Rr) flower. A pink offspring (F1) is bred with the same parent pink flower. What are the colors of the F2 offspring? [2 min] Red, pink, and white

Co-dominance No recessive allele

Question 10 What are the possible genotypes of the offspring from a Type A and a Type B person?