1 In southeast North Dakota there is a creature known as a w

1. In southeast North Dakota there is a creature known as a wildcat. It has three color phases: blue, which is homozygous (BB), red, which is homozygous (bb), and purple, which is heterozygous (Bb). What pattern of inheritance is observed in the color of this cat?

2. If a blue wildcat were crossed with a red one, what would the genotypes and phenotypes of the offspring be?

3. What type of wildcats would you mate if you only wanted red offspring?

4. A man with Type B blood marries a woman with Type O blood. A child in their home has Type A blood. Explain what you know about the individuals.

5. Normal vision in humans is dominant to color blindness and the alleles are found on the sex chromosomes. A normal man, whose father was color blind, marries a color blind woman. Normal=C; color blind=c. Give the genotypes of those involved: Man________________________ His Father_________________ His Wife __________________

6. In humans, the gene for hemophilia (h) is sex-linked recessive to the gene for normal blood (H). Show the genotypes of the following individuals: a. hemophiliac woman x a normal man b. normal (heterozygous) woman x hemophiliac man c. normal (homozygous) woman x hemophiliac man List the expected phenotypes and ratios resulting from the above crosses:

7. What is the genotype of a man who has freckles (dominant) and is color-blind, if his mother lacked freckles?

8. A man with a widow’s peak, whose mother was color blind and whose father had a continuous hairline, is engaged to marry a woman whose color blind mother had a continuous hairline, and whose normal visioned father had a continuous hairline.

a. what is the genotype of the young gentleman?

b. What is the genotype of his fiancée?

9. If the couple in the preceding problem marry and have a family, what are the chances of them having:
a. A normal visioned child with a continuous hairline?
b. A color blind child with a widow’s peak?

c. A normal visioned daughter with a continuous hairline?
d. A color blind son with a widow’s peak?

Solution

Q1. Since the blue wildcat (BB) and red wildcat (bb) are homozygous and are producing individual effects. But on mating, the heterozygous purple wildcat (Bb) is produced, which has dominance of none of the above homozygous cats and thus both the parents express their alleles. This type of inheritence is Incomplete inheritence.

Q2. If the blue wildcat (BB) mates with a red one (bb), three different offsprings will be produced in the ratio of 1:2:1. One will be blue in color (BB), one will be red in color (bb) and two will be purple in color (Bb) because of incomplete dominance.

Q3. A red homozygous wildcat (bb) if allowed to mate with a purple wildcat (Bb), it will produce two purple wilcats and two red wildcats in the ratio of 1:1.

Q4. The case of a man with type B blood group (either BB or BO) and a woman with type O blood group (OO) have a child of type A blood group (AA or AO). This example shows that the child is not of the male, since the offspring produced by this male can either have B or O blood group.