GENETICS MIDTERM SAMPLE QUESTIONS

College-Level Genetics Exam: Multiple-Choice Questions

Instructions: Select the best answer for each question.

1. What is the term for different forms of a gene found at the same locus on homologous chromosomes?

   • a) Genotype

   • b) Alleles

   • c) Chromatids

   • d) Phenotype

2. Which type of mutation results in a completely nonfunctional gene product?

   • a) Gain-of-function mutation

   • b) Neutral mutation

   • c) Loss-of-function mutation

   • d) Missense mutation

3. In incomplete dominance, the heterozygous phenotype is:

   • a) The same as the dominant phenotype

   • b) The same as the recessive phenotype

   • c) Intermediate between the two parental phenotypes

   • d) A completely new phenotype

4. The ABO blood group system is an example of:

   • a) Codominance

   • b) Incomplete dominance

   • c) Polygenic inheritance

   • d) Epistasis

5. Which type of mutation increases the function of a gene product?

   • a) Gain-of-function mutation

   • b) Silent mutation

   • c) Nonsense mutation

   • d) Loss-of-function mutation

6. Which of the following is an example of an X-linked recessive disorder?

   • a) Sickle cell anemia

   • b) Duchenne muscular dystrophy

   • c) Huntington’s disease

   • d) Marfan syndrome

7. What is the expected F2 phenotypic ratio in a monohybrid cross exhibiting complete dominance?

   • a) 1:1

   • b) 3:1

   • c) 9:3:3:1

   • d) 1:2:1

8. A heterozygote for an autosomal recessive disorder:

   • a) Has the disorder

   • b) Is a carrier but does not exhibit symptoms

   • c) Cannot pass the disorder to offspring

   • d) Will always produce affected offspring

9. Which type of mutation does NOT alter the amino acid sequence of a protein?

   • a) Nonsense mutation

   • b) Silent mutation

   • c) Frameshift mutation

   • d) Missense mutation

10. What is the term for a gene that affects multiple traits?

• a) Epistatic gene

• b) Polygenic gene

• c) Pleiotropic gene

• d) Modifier gene

11. What is the inheritance pattern where one gene completely masks the effect of another gene?

• a) Codominance

• b) Incomplete dominance

• c) Epistasis

• d) Pleiotropy

12. A woman with blood type A has a child with blood type O. What could be the father’s blood type?

• a) AB

• b) A

• c) B

• d) A or B

13. Which of the following is an example of polygenic inheritance?

• a) Blood type

• b) Skin color

• c) Hemophilia

• d) Cystic fibrosis

14. In a pedigree, a filled square represents:

• a) An unaffected male

• b) An affected male

• c) An affected female

• d) A carrier male

15. Which type of chromosomal mutation results in a segment of a chromosome being reversed?

• a) Deletion

• b) Duplication

• c) Inversion

• d) Translocation

16. What is the probability that two heterozygous parents will have a homozygous recessive child?

• a) 0%

• b) 25%

• c) 50%

• d) 75%

17. Which of the following is an example of a sex-influenced trait?

• a) Color blindness

• b) Hemophilia

• c) Pattern baldness

• d) Cystic fibrosis

18. What determines maleness in humans?

• a) Presence of two X chromosomes

• b) Presence of the SRY gene on the Y chromosome

• c) Absence of the X chromosome

• d) Number of autosomes

19. What is the primary function of the XIST gene in dosage compensation?

• a) Activates the X chromosome

• b) Inactivates one X chromosome in females

• c) Increases expression of Y-linked genes

• d) Regulates autosomal gene expression

20. A mutation that results in an early stop codon is called:

• a) Missense mutation

• b) Silent mutation

• c) Nonsense mutation

• d) Frameshift mutation

21. What is the function of a test cross in genetics?

• a) To determine the phenotype of an organism

• b) To determine the genotype of an organism with a dominant phenotype

• c) To identify linked genes

• d) To map chromosomes

22. A person with genotype IAIB has which blood type?

• a) A

• b) B

• c) AB

• d) O

23. A man with hemophilia (X-linked recessive) and a normal woman will have:

• a) All sons with hemophilia

• b) All daughters as carriers and all sons normal

• c) Half of daughters with hemophilia

• d) Half of sons with hemophilia

24. Which of the following is an example of a genetic disorder caused by a deletion?

• a) Sickle cell anemia

• b) Cri-du-chat syndrome

• c) Cystic fibrosis

• d) Huntington’s disease

25. In which type of inheritance do heterozygous individuals exhibit both traits simultaneously?

• a) Incomplete dominance

• b) Codominance

• c) Epistasis

• d) Pleiotropy

26. What does the principle of independent assortment state?

• a) Genes do not assort independently

• b) Only dominant traits are inherited

• c) Genes for different traits segregate independently during gamete formation

• d) Linked genes always assort together

27. Which of the following is an example of an autosomal dominant disorder?

• a) Hemophilia

• b) Cystic fibrosis

• c) Marfan syndrome

• d) Duchenne muscular dystrophy

28. What is the process called when homologous chromosomes exchange genetic material?

• a) Segregation

• b) Crossing over

• c) Independent assortment

• d) Linkage

29. Which of the following describes a frameshift mutation?

• a) Substitution of one nucleotide

• b) Silent mutation

• c) Insertion or deletion of nucleotides shifting the reading frame

• d) Point mutation

30. What is a Barr body?

• a) An inactivated Y chromosome

• b) A mutated gene

• c) An inactivated X chromosome in females

• d) A mitochondrial DNA mutation

31. Which of the following disorders is caused by a trinucleotide repeat expansion?

• a) Cystic fibrosis

• b) Huntington’s disease

• c) Sickle cell anemia

• d) Turner syndrome

32. In a dihybrid cross, what is the expected phenotypic ratio of offspring when both parents are heterozygous for both traits?

• a) 1:2:1

• b) 9:3:3:1

• c) 3:1

• d) 1:1

33. Which organelle contains its own DNA and can pass genetic traits maternally?

• a) Nucleus

• b) Mitochondria

• c) Lysosome

• d) Golgi apparatus

34. What does genetic anticipation refer to?

• a) Genes skipping generations

• b) Increasing severity and earlier onset of a genetic disorder in successive generations

• c) Mutations occurring after birth

• d) New alleles forming in each generation

35. Which of the following is an example of extranuclear inheritance?

• a) X-linked disorders

• b) Codominance

• c) Mitochondrial DNA inheritance

• d) Polygenic traits

36. What is the purpose of a pedigree analysis?

• a) To analyze protein function

• b) To track inheritance of genetic traits in families

• c) To sequence DNA

• d) To observe gene expression

37. In sex-limited inheritance, traits appear:

• a) Equally in both sexes

• b) Only in one sex, despite both sexes carrying the genes

• c) Only in males

• d) Only in females

38. What is the most common method of dosage compensation in humans?

• a) Doubling gene expression in males

• b) Reducing gene expression in females

• c) X-chromosome inactivation

• d) Y-chromosome amplification

39. What type of genetic material is typically involved in epigenetic regulation?

• a) Only DNA sequence changes

• b) Mitochondrial DNA

• c) DNA methylation and histone modification

• d) RNA mutations

40. What happens in individuals with Klinefelter syndrome?

• a) They have a single X chromosome

• b) They lack sex chromosomes

• c) They have an extra X chromosome (XXY karyotype)

• d) They inherit a Y-linked disorder

41. Which of the following is an example of a sex-influenced trait?

• a) Color blindness

• b) Hemophilia

• c) Pattern baldness

• d) Cystic fibrosis

42. What is the primary function of a centromere?

• a) Codes for proteins

• b) Protects DNA from mutation

• c) Attaches sister chromatids together

• d) Facilitates crossing over

43. Which of the following best describes a silent mutation?

• a) A mutation that changes the amino acid sequence

• b) A mutation that does not change the amino acid sequence

• c) A mutation that leads to a frameshift

• d) A mutation that introduces a stop codon

44. Which genetic disorder is caused by the absence of dystrophin?

• a) Cystic fibrosis

• b) Huntington’s disease

• c) Duchenne muscular dystrophy

• d) Marfan syndrome

45. What is a major characteristic of Turner syndrome?

• a) Trisomy 21

• b) Extra Y chromosome

• c) Monosomy X

• d) XXY karyotype

46. What is a translocation mutation?

• a) A single base change

• b) A segment of a chromosome moving to a non-homologous chromosome

• c) A repeated DNA sequence

• d) A loss of genetic material

47. What is the purpose of a karyotype analysis?

• a) To identify mutations at the molecular level

• b) To visualize chromosome structure and number

• c) To determine an organism’s phenotype

• d) To measure gene expression

48. Which of the following is a Y-linked trait?

• a) Color blindness

• b) Hemophilia

• c) Cystic fibrosis

• d) Male infertility

49. What role does the SRY gene play in human development?

• a) Prevents male differentiation

• b) Triggers testes development

• c) Controls red blood cell production

• d) Regulates female reproductive development

50. What is the most common cause of Down syndrome?

• a) X-inactivation

• b) Deletion of chromosome 21

• c) Nondisjunction leading to trisomy 21

• d) Expansion of a trinucleotide repeat

51. Which of the following describes the function of telomerase?

• a) Repairs DNA replication errors

• b) Maintains the ends of chromosomes

• c) Facilitates recombination

• d) Destroys abnormal cells

52. What is an example of genomic imprinting?

• a) Prader-Willi syndrome

• b) Cystic fibrosis

• c) Sickle cell anemia

• d) Turner syndrome

53. Which term refers to multiple genes influencing a single trait?

• a) Pleiotropy

• b) Polygenic inheritance

• c) Codominance

• d) Epistasis

54. Which of the following is a characteristic of mitochondrial inheritance?

• a) Follows Mendelian inheritance

• b) Passed only through the mother

• c) Affects only males

• d) Involves recombination during meiosis

55. What is a characteristic of Fragile X syndrome?

• a) Deletion mutation

• b) Trinucleotide repeat expansion

• c) Y-linked inheritance

• d) Autosomal dominant pattern

56. What is the primary mechanism of gene regulation in prokaryotes?

• a) RNA splicing

• b) Operon systems

• c) Alternative polyadenylation

• d) Chromatin modification

57. What is aneuploidy?

• a) Mutation within a single gene

• b) An abnormal number of chromosomes

• c) Change in the nucleotide sequence

• d) Exchange of genetic material

58. Which of the following disorders is an example of a dominant lethal allele?

• a) Cystic fibrosis

• b) Huntington’s disease

• c) Sickle cell anemia

• d) Hemophilia

59. Which of the following is an example of a structural chromosomal mutation?

• a) Nondisjunction

• b) Inversion

• c) Point mutation

• d) Missense mutation

60. What is the function of the lac operon in E. coli?

• a) Inhibits glucose metabolism

• b) Regulates lactose metabolism

• c) Produces ribosomal RNA

• d) Repairs DNA damage

College-Level Genetics Exam: Multiple-Choice Questions (Part 4)

Instructions: Select the best answer for each question.

61. Which of the following is an example of a gene that exhibits pleiotropy?

• a) ABO blood group gene

• b) Hemoglobin gene

• c) Marfan syndrome gene

• d) Rh factor gene

62. What process leads to genetic variation during meiosis?

• a) DNA replication

• b) Crossing over and independent assortment

• c) Transcription

• d) Translation

63. What type of inheritance pattern is seen in sickle cell anemia?

• a) Autosomal dominant

• b) Autosomal recessive

• c) X-linked recessive

• d) Mitochondrial inheritance

64. Which of the following describes a nonsense mutation?

• a) A mutation that does not affect protein function

• b) A mutation that introduces a premature stop codon

• c) A mutation that causes a frameshift

• d) A mutation that results in silent gene expression

65. Which RNA molecule is responsible for carrying amino acids to ribosomes?

• a) mRNA

• b) rRNA

• c) tRNA

• d) siRNA

66. What is the function of histones in eukaryotic cells?

• a) Direct protein synthesis

• b) Regulate gene transcription

• c) Package and condense DNA into chromatin

• d) Catalyze DNA replication

67. Which of the following is an example of a polygenic trait?

• a) ABO blood type

• b) Human height

• c) Cystic fibrosis

• d) Color blindness

68. What is the expected phenotypic ratio for a dihybrid cross where both parents are heterozygous for two traits?

• a) 3:1

• b) 9:3:3:1

• c) 1:2:1

• d) 1:1

69. Which enzyme is responsible for unwinding the DNA double helix during replication?

• a) DNA polymerase

• b) Helicase

• c) Ligase

• d) Primase

70. Which type of mutation results in an entire codon being deleted, potentially altering protein structure?

• a) Missense mutation

• b) Silent mutation

• c) Deletion mutation

• d) Duplication mutation

71. Which of the following is true about genetic drift?

• a) It only affects dominant traits

• b) It increases genetic variation

• c) It occurs due to random chance events

• d) It only occurs in large populations

72. Which of the following describes the bottleneck effect?

• a) When a population rapidly expands

• b) When a population undergoes a drastic reduction in size

• c) When new mutations arise

• d) When genetic recombination occurs

73. What is the role of DNA ligase in replication?

• a) Adds nucleotides to the growing strand

• b) Joins Okazaki fragments together

• c) Unwinds the DNA strand

• d) Synthesizes the RNA primer

74. What is a telomere?

• a) A protein that assists in DNA replication

• b) A sequence in the middle of a chromosome

• c) A protective cap at the ends of chromosomes

• d) A type of RNA molecule

75. Which process results in the formation of haploid gametes?

• a) Mitosis

• b) Meiosis

• c) Binary fission

• d) Transcription

76. Which of the following is an example of post-transcriptional modification?

• a) DNA replication

• b) Splicing of introns

• c) Addition of a poly-A tail

• d) Ribosome assembly

77. What is the primary function of the p53 gene?

• a) Regulates X-inactivation

• b) Activates telomerase

• c) Suppresses tumor formation

• d) Increases the rate of cell division

78. Which of the following is an example of convergent evolution?

• a) Whales and sharks having similar body shapes

• b) Wings in bats and birds evolving independently

• c) Humans and chimpanzees sharing a common ancestor

• d) Bacteria developing antibiotic resistance

79. What is the significance of Hox genes in development?

• a) They control metabolic pathways

• b) They regulate body plan formation

• c) They initiate DNA replication

• d) They suppress harmful mutations

80. What is gene therapy used for?

• a) Preventing mitosis

• b) Increasing mutation rates

• c) Treating genetic disorders by altering DNA

• d) Stopping protein synthesis