Genetics Prac Prob #6 Sex-linked



Genetics Practice Problems – Sex Linkage Worksheet

Directions: Use these genotypic symbols for the sex linked trait of red-green color blindness in humans to solve the problems that follow. Show your work.

|"Normal" female |XCXC |Normal male |XCY |

|Carrier female |XCXc |Color-blind Male |XcY |

|Color-blind female |XcXc | | |

1. A normal female marries a color blind male.

(A) What are the chances that the offspring will be color blind if they are females?

(B) What are the chances that the offspring will be color blind if they are males?

| | |

| | |

A. ____________

B. ____________

2. A color-blind female marries a normal male.

(A) How many of the female offspring will be carries of the color-blind allele?

| | |

| | |

A. ____________

3. A carrier female marries a normal male.

(A) How many of the male offspring can be expected to be color-blind?

(B) How many of the male offspring can be expected to have normal vision?

(C) How many of the female offspring can be expected to be carriers?

(D) How many of the female offspring can be expected to be normal?

A. ____________

B. ____________

C. ____________

D. ____________

4. A man whose mother is color blind marries a woman with normal vision. (A) What is the genotype of the husband? (B) What percent of their offspring can be expected to be color-blind? (C) What percent of the male offspring can be expected to be color-blind? (D) What percentage of their offspring can be expected to be carriers?

A. ____________

B. ____________

C. ____________

D. ____________

5. The X-linked barred locus in chickens controls the pattern of the feathers, with the alleles B for barred pattern and b for no bars.

If a barred male (XBY) is mated to a nonbarred female (XbXb), what will be the appearance of the (A) male and (B) female progeny?

A. ___________

B. ____________

6. A particular sex-linked recessive disease of humans isn't usually fatal. Suppose that a boy with the disease lives past puberty and marries a woman heterozygous for the trait.

(A) If they have a daughter, what is the probability that she will have the disease? Hint: first determine the genotypes of the parents, then construct Punnett Square of cross, and analyze the results.

A. ____________

7. Hemophilia is an X-linked, recessive disorder. If a hemophilic male mates with a heterozygous female, (A) what percentage of their sons will be hemophilic? (B) What percentage of their daughters will be hemophilic?

A. ____________

B. ____________

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download