Mendelian Genetics Problems Name ___________________ Period ___

1A. The gene for hair color in rabbits has two alleles Q and q. Q is dominant and codes for brown hair. q is recessive and codes for white hair. Write out all the possible genotypes.

1B. Using the above example, fill in the Punnett's Square of offspring genotypes if one parents is heterozygous and the other is white haired. If the pair of rabbits have a litter of 24 babies, write out the expected number of each genotype and phenotype in the table below.

2A. The gene for plant height in sunflowers has two codominant alleles T₁ for tall plants and T₂ for short plants. If a tall plant is crossed with a short plant, fill in the table below.

2B. Take any two of the seedlings from part 2A and cross them. Fill in the results below.

3A. Sex expression in humans is controlled by the X and Y chromosomes. Females are XX and males are XY. Since cells of the body contain 46 chromosomes, mom must give 23 to baby and dad must give 23 as well. Mom gives 1 sex chromosome to each of her eggs along with 22 body chromosomes. Dad gives 1 sex chromosome to each of his sperm along with 22 body chromosomes. Fill in the possible sex chromosomes contributed to sperm and egg in the table below. If mom and dad have 8 kids, show the expected number of boys and girls below:

3B. Why do some families end up with unequal sex ratios (more boys or girls)?

3C. Colorblindness is a recessive trait caused by an error on the X chromosome. X_A=Normal Vision and X_a=Colorblind. If mom is normal (not a carrier) and dad is colorblind, fill in the table below:

4. In guinea pigs, two different genes affect the coat. One gene codes for coat color and there are 2 codominant alleles C₁=Brown and C₂=White. The second gene codes for presence of hair with H=hairy (dominant) and h=hairless (recessive). If mom is C₁C₂hh and dad is brown and heterozygous for hairiness, fill in the table below.