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Human Genetics Web Tutorial




True/False

Indicate whether the sentence or statement is true or false.

TF 1. Hemophilia is a recessive, sex-linked disorder.

TF 2. An autosomal trait will occur with equal frequency in both males and females.

TF 3. Sex-linkd traits appear more often in females than in males.

TF 4. An individual who expresses a genetic disorder is called a carrier.

TF 5. A male can produce sperm that contains either an X or a Y chromosome.

TF 6. Mutations are always harmful.

TF 7. A pedigree is a family record that shows how a trait is inherited over several generations.



Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.

8. Hemophilia is a genetic disorder that is
a. sex-linked. c. fairly common.
b. sex-influenced. d. more common in women than in men.



9. Parents of a color blind female could have the genotypes
a. XCXc and XCY c. XCXc and XcY
b. XcXc and XCY d. XCXC and XcY



10. People who are heterozygous for sickle cell anemia are
a. partially resistant to the effect of ultraviolet radiation.
b. totally resistant to the effect of ultraviolet radiation.
c. partially resistant to malaria.
d. totally resistant to malaria.



11. Both sickle cell anemia and hemophilia
a. are caused by genes coding for defective proteins.
b. are seen in homozygous dominant individuals.
c. provide resistance to malaria infections.
d. are extremely common throughout the world.



12. This genetic disease occurs most frequently in the black population.
a. cystic fibrosis c. sickle-cell anemia
b. Tay-Sachs disease d. hemophilia



13. The trait for skin color in humans is cause by
a. crossing-over c. nondisjunction
b. multiple genes d. mutations



14. A hereditary disease in which the red blood cells have an abnormal shape is
a. galactosemia c. polydactyly
b. Tay-Sachs disease d. sickle-cell anemia



15. Sex-linked traits appear more often in males than in females because
a. males are produced in greater numbers
b. females with a sex-linked trait will die
c. males have only one X chromosome
d. sex-linked traits are carried on the Y chromosome


16. A diagram in which several generations of a family and the occurrence of certain genetic characteristics are shown is called a
a. Punnett square. c. pedigree.
b. monohybrid cross. d. family karyotype.



17. What is the percentage of chance that two people who carry a sickle-cell gene will have a child having the disease?
a. 0 c. 50
b. 25 d. 100



18. Which genetic trait is most influenced by the environment?
a. blood type c. baldness
b. eye color d. weight


19. Very dark-skinned people have alleles at all gene positions for skin color that code for
a. red-green colorblindness. c. the production of Rh antigens.
b. albinism. d. the production of melanin.



20. Sex-linked traits such as color blindness
a. are never carried by females c. occur more frequently in males
b. occur more frequently in females d. never occur in males



21. What would be the blood type of a person who inherited an A allele from one parent and an O allele from the other?
a. type A c. type AB
b. type B d. type O.



22. Genetic counseling is a process that
a. helps identify parents at risk for having children with genetic defects.
b. assists parents in deciding whether or not to have children.
c. uses a family pedigree.
d. All of the above


23. If both parents carry the recessive allele that causes cystic fibrosis, the chance that their child will develop the disease is
a. one in two. c. two in five.
b. one in four. d. 100 percent.



24. People with Down syndrome have
a. 45 chromosomes. c. 47 chromosomes.
b. 46 chromosomes. d. no X chromosomes.



25. If nondisjunction occurs,
a. there will be too many gametes produced.
b. no gametes will be produced.
c. a gamete will receive too many or too few homologues of a chromosome.
d. mitosis cannot take place.



26. A human female inherits
a. one copy of every gene located on each of the X chromosomes.
b. twice as many sex chromosomes as a human male inherits.
c. one copy of every gene located on the Y chromosome.
d. all of the same genes that a human male inherits.



27. A pedigree CANNOT be used to
a. determine whether a trait is inherited.
b. show how a trait is passed from one generation to the next.
c. determine whether an allele is dominant or recessive.
d. none of the above


28. If a man with blood type A and a woman with blood type B produce an offspring, what might be the offspring’s blood type?
a. AB or O
b. A, B, or O
c. A, B, AB, or O
d. AB only



29. Sickle cell disease is caused by a
a. change in one DNA base.
b. change in the size of a chromosome.
c. change in two genes.
d. change in the number of chromosomes in a cell.

30. Many sex-linked genes are located on
a. the autosomes.
b. the X chromosome only.
c. the Y chromosome only.
d. both the X chromosome and the Y chromosome.