1. The human's somatic cells are diploid. Each cell contains 22 pair (44) autosomes and 1 pair (2) sex chromosomes. These sex chromosomes may be designated as XY.
Press here to go back to home page. press
2. There would be only 22 autosomes in the sperm cell of the human male.
Press here to go back to home page. press
3. The correct answer is "d". 44 autosomes and 2 X chromosomes.
Press here to go back to home page. press
4. The correct answer is "b". 44 autosomes, 1 X and 1 Y chromosome.
Press here to go back to home page. press
5. The correct answer is "a". 22 autosomes, 1 X chromosome.
Press here to go back to home page. press
6. The correct answer is "a". 22 autosomes, 1 X or 1 Y chromosome.
Press here to go back to home page. press
7.
| ////////////////////// | X | Y |
| X | XX | XY |
| X | XX | XY |
Press here to go back to home page. press
8. Since it is the Y chromosome that determines the sex of the child in humans and the male produces X sperm and Y sperm, the father determines the sex of the individual.
Press here to go back to home page. press
9. No. Since the Y chromosome is nonfunctional, whatever allele is located on the male's X chromosome will determine the phenotype.
Press here to go back to home page. press
10. The red-eyed female parent must have at least one dominant allele (XR) and the red-eyed male parent also must have one dominant allele (XR). Since some of the male offspring have white eyes, the female parent must be XRXr in order to pass the Xr allele to its males. There are no white eye females because the red-eyed male parent can not pass a Xr to its daughters.
Genotypes of the parents are: XRXr (female) and XRY (male)
Check the Punnett square below.
| /////////////////// | XR | Xr |
| XR | XRXR | XRXr |
| Y | XRY | XrY |
Press here to go back to home page. press
11. Since there are white eyed females both parents must have a Xr , and since there are red-eyed females the male parent must have a XR , and since there ar red eyed males the female parent must have a XR.
Therefore the parents have the following genotypes. XRXr (female) and XrY (male)
Check the Punnett square below.
| /////////////////// | XR | Xr |
| Xr | XRXr | XrXr |
| Y | XrY | XrY |
Press here to go back to home page. press
12. Since the male parent is normal his genotype is XN and since the female parent is normal but produces children which are colored blind she is a carrier (heterozygous) XNXn.
Therefore the parent's genotype are XNXn (female) and XNY (male)
Press here to go back to home page. press
13. The father's genotype does not make any difference. In sex-linked
traits the female determines the phenotype and genotype of the boys. The
father only passes on the Y chromosome.
Press here to go back to home page. press
14. One half of the sperm will contain the Xh chromosome and allele. The other half sperm will contain the Y chromosome.
Press here to go back to home page. press
15. One half of the female's eggs will contain the dominant allele - XH. The other half will contain the recessive allele.
Press here to go back to home page. press
16. Parents
XHXh X
XhY
| /////////////////// | XH | Xh |
| Xh | XHXh | XhXh |
| Y | XHY | XhY |
The chances for the boys to have hemophilia are 50 % and the chances the girls have hemophilia are 50 %.
Press here to go back to home page. press
17.
Press here to go back to home page.
Press here to go back to home page.
Press here to go back to home page.
Press here to go back to home page.
Press here to go back to home page.
Press here to go back to home page.
Press here to go back to home page.
Press here to go back to home page.
For information on how to use this page, go to How
to Use This Site.
Created by the Center for Learning Technologies, Academic Technology Services.
Last modified October 22, 1997.