More Genetics Problems – The whole shebang!!!

  1. In a flea species, long antenna dominates short antenna, and black colour is dominant to white.
  2. Cross two heterozygous black fleas with long antenna. Predict the F2.
  3. Cross a heterozygous black flea with long antenna with a flea that is completely recessive. Predict the F2.
  4. Cross two fleas that are dominant for both traits. Predict the F2.
  1. Galactosemia is a recessive trait in a man. A normal couple has an affected child. What is the probability that :
  2. The next child will be normal?
  3. The next child will be galactosomic?
  4. The father of this family is galactosomic?
  5. The father of this family is heterozygous for galactosemia?
  1. Draw a pedigree chart for question 2.
  1. In mice the gene (N) for normal behavior of dominant over the gene for (n) shy behavior. The gene (R) for rumba is dominant over that for waltzing (r). If a mouse is homozygous for normal behavior and waltzing, mated with a mouse that is shy and rumbas, how would their offspring behave at a dance?
  1. In cats, solid black fur (a) is recessive to wild tiger pattern (A). Tail length of cats is governed by incomplete dominance, as TT is the genotype of a tailless cat, tt for a normal long tailed cat, and Tt for a bobtailed cat. What will be the phenotypes among the offspring of the following matings:
  1. aaTt x Aattb. aatt x AaTt
  1. A Roan is a bovine that has intermingled red and white hair. This is an example of co-dominance. It comes as a result of a red bull mating with a white cow. Predict the genotypes and phenotypes for:
  2. A roan bull with a roan cow
  3. A roan bull with a white cow
  1. Explain why undesirable traits due to dominant alleles are more easily eliminated from a population than those due to recessive alleles.
  1. What would be the blood type of the offspring of the following combinations of parents?
  1. A type O male with a AB female
  2. A homozygous type B male and a heterozygous type A female
  1. A baby is born with blood type B, his mother is blood type A, his paternal grandfather was type A, and his paternal grandmother was type B. What are the possible genotypes of the father and all the others, including the baby?
  1. In horses, the trotter characteristic is dominant to the pacer characteristic. A male trotter mates with three different females, and each female produces a foal. The first female, a pacer, give birth to a foal that is a pacer. The second female, also a pacer, gives birth to a foal that is a trotter. The third female, a trotter, gives birth to a foal that is a pacer. Determine the genotypes of the male, all three females and the three foals sired.
  1. A tarsus rat was taken from a group that was known to breed for black and straight hair. It was then bred with a rat of unknown genotype and the offspring were:

Black and straight hair / 1315
Red and curly hair / 1370
Red and straight hair / 21
Black and curly hair / 19

Determine the genotype of the unknown parent and give a genetic explanation of the results. Based upon your explanation, do a chi-square test on the data.

  1. In the Dead Sloe, the allele for round fruit is dominant over long fruit and the allele for complex flower is recessive to simple flower. A cross was made between the two varieties, Purple pear (long fruit and simple flower) and grape cluster (round fruit and complex flower). All of the F1 plants had simple flowers and produced round fruit. A test cross on the F1 gave the following results:

Simple flowers, round fruit / 23
Simple flowers, long fruit / 93
Complex flowers, round fruit / 89
Complex flowers, long fruit / 19

Explain these results fully. Identify the recombinant plants.

If the alleles were not linked, what numbers would you predict for each phenotype of the F1 plants had been allowed to self pollinate. Explain your results.

Do a chi-square test on the data.