Genetics Questions

1) In a cross between a heterozygous tall pea plant and a dwarf pea plant, what will the offspring’s genotype and phenotype ratios be?
2) In pea plants, pod shape is controlled by a single gene with 2 alleles with the dominant allele (F) producing full pods and the recessive (f) producing constricted pods. You cross 2 individuals with full pods and get 150 with full pods and 35 with constricted pods. Test the hypothesis that the parental genotypes were Ff and Ff using a chi-square test.
3) In cocker spaniels, solid coat color is dominant over spotted coat color. If 2 heterozygous dogs were crossed, what would be the probability of the following combinations?
a. A litter of 5 pups, 4 with solid fur and 1 with spotted fur?
b. A litter of 6 pups, 4 with solid fur and 2 with spotted fur?
4) 4) A woman with achondroplasia (a dominant form of dwarfism) and a phenotypically unaffected man have 7 children, all of whom have achondroplasia.
a. What is the probability of producing such a family if this woman is a heterozygote?
b. If they have an 8th child that does not have achondroplasia, what is the probability of the woman being a heterozygote?
5) You encounter a group of zebrafish siblings with the following phenotypes:
50 non-ghost, non-dracula
26 ghost, non-dracula
25 non-ghost, dracula
12 ghost, dracula
Using your knowledge of Mendelian genetics and a chi-square test, figure out what the most likely genotypes of the parent are. (Note: ghost and dracula are both recessive phenotypes)
6) While working on a project looking at zebrafish genetics, you discover 2 new mutants! The first, werewolf, is caused by a recessive allele, and individuals homozygous for this allele grow large amounts of hair all over their bodies. The second mutation, godzilla, is caused by a dominant allele and causes individuals to be able to project fire from their mouth. You cross 2 fish with the following genotypes:
GGDDWwzz x GgddWwZz
What is the probability of a non-ghost, non-dracula, werewolf, godzilla offspring?
7) Which blood phenotypes (A, B, AB, and O) can be attributed to a single genotype? Is it possible for a couple to have a group of children with all 4 blood types represented? If yes, what are the parent’s genotypes?
8) Hemophilia is an X-linked recessive trait in humans. If a heterozygous woman has children with an unaffected man, what is the probability of _____________.
a. an affected son?
b. 4 unaffected offspring in a row?
c. an unaffected daughter or son?
d. 2 unaffected children out of 5
9) A woman heterozygous for the X-linked allele that causes for Duchenne muscular dystrophy has children with a man with a normal allele. What are the probabilities of:
a. an unaffected son?
b. an unaffected son or daughter?
c. having 3 children, all of whom are affected?
10) Four-o’-clocks show incomplete dominance in regard to flower color. The genotype RR produces red flowers, Rr produces pink flowers, and rr produces white flowers. If you cross 2 pink four-o’-clocks, what would the following probabilities be?
a. an offspring would be white or pink
b. the first 3 offspring would be red
c. there would be 6 offspring, 1 pink, 2 white, and 3 red

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