What is the probability that a second child | Homework Helpers

1. Saguaro cacti have 2 L-shaped arms and you have one with arms that are different lengths. Arm length in the cactus is controlled by one gene. Arms of the same length (A) are dominant to arms of a different length (a). What is the genotype of our cactus? If you cross our cactus with your neighbor’s cactus which has arms of the same length and ½ of the offspring have different length arms. What is the genotype of the neighbor’s cactus?

2. The ability to curl your tongue up on the sides (T, tongue rolling) is dominant to not being able to roll your tongue (t). A woman who can roll her tongue marries a man who cannot. Their first child has his father’s phenotype. What are the genotypes of the mother, father, and child? What is the probability that a second child will be a tongue roller?

3. A boy, whose parents and grandparents had normal vision is color blind. What are the genotypes of his mother and his maternal grandparents? (B = normal vision; bb = color blind)

4. The lubber grasshopper is a very large grasshopper, and is black with red and yellow stripes. Assume that red stripes are expressed from the homozygous RR genotype, yellow stripes from the homozygous rr genotype and both from the heterozygous Rr genotype. What will be the phenotypic ration of the F1 generation resulting from a cross of two grasshoppers, both with red and yellow stripes (Rr x Rr)? What would be the genotypic ration of the F1 generation? What phenotypes would be produced by crossing a grasshopper with both color stripes and one with only yellow stripes?

5. Coat color in cats is a codominant trait and is also located on the X chromosome. Cats can be black, yellow or calico. A calico cat has black and yellow splotches. In order to be calico, the cat must have an allele for the black color and an allele for the yellow color. Use a punnet square to show why there are no male calico cats.

6. Consider an individual who has type O blood. Her brother has type AB. Her father’s sister has type AB blood, and her father’s father had a BB genotype. Her mother’s sister has type O blood, and her mother’s brother has type B blood. What are the genotypes of her mother, father and her four grandparents?