Genetics Exam 2

Section I: DNA Replication and Organization

1. Which of the following best describes semiconservative replication?
   A. Both strands of DNA are newly synthesized
   B. Both strands of DNA are from the original molecule
   C. Each new DNA molecule contains one old and one new strand
   D. Each strand is randomly assembled from old and new nucleotides

2. What is the role of DNA polymerase in replication?
   A. It breaks hydrogen bonds between bases
   B. It adds nucleotides to the growing DNA strand
   C. It unwinds the DNA helix
   D. It forms histones

3. Nucleosomes are made up of:
   A. DNA and RNA
   B. DNA wrapped around histones
   C. RNA bound to chromatin
   D. Purines and pyrimidines only

4. What is the function of telomerase?
   A. Breaks DNA strands
   B. Adds repeating DNA sequences to chromosome ends
   C. Transcribes genes
   D. Links histones together

5. Which bond holds the two strands of DNA together?
   A. Peptide bonds
   B. Ionic bonds
   C. Hydrogen bonds
   D. Covalent bonds

Section II: Development and Sex Determination

6. Which gene is responsible for triggering the formation of testes in embryos?
   A. AMH
   B. SRY
   C. FAS
   D. Xic

7. Which of the following is true about dosage compensation?
   A. Females express twice as many X-linked genes as males
   B. Only one X chromosome is active in each female somatic cell
   C. Dosage compensation does not occur in mammals
   D. Males have two Barr bodies

8. What is the Barr body?
   A. A cluster of mitochondria
   B. A tightly coiled Y chromosome
   C. An inactivated X chromosome
   D. A modified centromere

9. Which syndrome is caused by complete androgen insensitivity in an XY individual?
   A. Klinefelter syndrome
   B. Turner syndrome
   C. CAIS
   D. Fragile-X syndrome

10. The Anti-Müllerian hormone (AMH) is responsible for:
    A. Promoting ovary development
    B. Initiating menstruation
    C. Causing degeneration of female ducts in male embryos
    D. Forming Barr bodies in males

Section III: Cytogenetics

11. Which of the following describes a metacentric chromosome?
    A. Centromere near the end
    B. Centromere at the center
    C. Lacks a centromere
    D. Two centromeres

12. A karyotype is:
    A. A map of DNA sequences
    B. A visual display of chromosomes arranged by size and shape
    C. A type of polygenic trait
    D. A technique used to measure gene expression

13. Which condition is an example of trisomy?
    A. Turner syndrome
    B. Cri du chat syndrome
    C. Trisomy 21
    D. Fragile-X syndrome

14. Nondisjunction during meiosis can cause:
    A. Mutations in RNA
    B. Trisomy and monosomy
    C. Histone malfunctions
    D. Changes in nitrogen bases

15. What does amniocentesis test for?
    A. Hormone levels in adults
    B. Genetic and developmental defects in a fetus
    C. Number of mitochondria in the egg
    D. The function of the placenta

Section IV: Complex Traits

16. Which of the following best describes a complex trait?
    A. A trait caused by a single gene
    B. A trait influenced only by the environment
    C. A trait involving multiple genes and environmental factors
    D. A trait found only in males

17. A good example of a discontinuous trait is:
    A. Eye color
    B. Height
    C. Tongue rolling
    D. Skin pigmentation

18. A trait with continuous variation would show:
    A. Clear-cut phenotypic classes
    B. A bell-shaped distribution of values
    C. One or two distinct types only
    D. No genetic influence

19. Which of the following best defines polygenic traits?
    A. Traits caused by mitochondrial DNA
    B. Traits affected by a single dominant allele
    C. Traits controlled by two or more genes
    D. Traits only found on sex chromosomes

20. Which best describes regression to the mean?
    A. When traits revert to the recessive form
    B. Offspring of extreme phenotypes tend to have average traits
    C. A mutation causes extreme phenotypes to disappear
    D. Trait values always increase in the next generation

21. Heritability measures:
    A. The percent of DNA inherited from the mother
    B. The degree to which environment affects a trait
    C. How much of a trait’s variation is due to genetics
    D. The number of genes on a chromosome

22. Epigenetics involves:
    A. Mutations in the DNA sequence
    B. Permanent changes to chromosomes
    C. Reversible changes that affect gene expression
    D. Loss of chromosomes in somatic cells

23. Monozygotic twins are:
    A. Genetically identical
    B. Produced from two different sperm and eggs
    C. Genetically unrelated
    D. Always fraternal

24. A high concordance rate in MZ twins suggests:
    A. No genetic basis for the trait
    B. A strong environmental component
    C. A genetic component to the trait
    D. Random mutation

25. The correlation coefficient is used to:
    A. Identify autosomal traits
    B. Measure the degree of similarity between traits
    C. Map chromosomes
    D. Count Barr bodies