A heterozygous purple plant is crossed with a white plant. A. Write the genotype of the purple and white plants. B. Write the gametes formed by the purple plant and proportions in which they occur. C. Write the gametes formed by the white plant and proportions in which they occur.
6. A heterozygous purple plant is crossed with a white plant.
A. Write the genotype of the purple and white plants.
B. Write the gametes formed by the purple plant and proportions in which they occur.
C. Write the gametes formed by the white plant and proportions in which they occur.
D. Combine the gametes using a Punnett square.
E. Write the genotypes of the offspring and the ratio in which they occur.
F. Write the
7. The ability to roll your tongue (R) is dominant to lack of this ability (r).
A. What is the genotype of a man who can roll his tongue if his father couldn’t?
B. If a man who is heterozygous for tongue rolling marries a woman who is heterozygous, what would you predict for the genotypes and phenotypes of their children?
8. Huntington’s disease is a degenerative disease of the nervous system that strikes in middle age. The allele that causes the disease (H) is dominant to the allele that results in the normal condition (h). Answer the following questions about the inheritance of this disease.
A. What is the genotype of a man who is normal but whose father had Huntington’s disease?
B. What is the genotype of a woman who has Huntington’s disease if both of her parents had Huntington’s disease?
C. If a man who is heterozygous for Huntington’s disease marries a woman who is normal, what would you expect for the genotypes and phenotypes of their children?
D. If a normal man marries a woman who is homozygous for Huntington’s disease, what do you expect for the genotypes and phenotypes of their children?
9. The factors for normal hemoglobin (S) and sickle-cell hemoglobin (s) are considered codominants: heterozygous individuals have some normal red blood cells and some sickle cells but are not considered to have the disease. A heterozygote is said to have the sickle-cell trait but not the disease.
A. What is the genotype of a man with the sickle-cell trait?
B. If normal man marries a heterozygous woman, what do you expect for the genotypes and phenotypes of their children?
C. If 2 heterozygous people marry and have 3 children who don’t have the disease, what is the chance that their fourth child will have the disease?
D. Assume that medical science finds a treatment for sickle-cell anemia so that people with the disease can live out a normal life span but their genes are not changed. If 2 people are saved from the effects of the disease, marry, and have children, what would you expect for the genotypes and phenotypes of their children? Would the children require treatment like their parents did?
10. In snapdragons, red is caused by an allele R and white by an allele r. The heterozygote (Rr) is neither red nor white but instead is pink.
A. What genotypes are possible for a white flower?
B. What would you predict for the genotypes and phenotypes of the offspring from a red and a white flower?
C. What would expect from the cross of two pink flowers?
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