16. What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
(A) It synthesizes RNA nucleotides to make a primer.
(B) It joins Okazaki fragments together.
(C) It unwinds the parental double helix.
(D) It stabilizes the unwound parental DNA.

12. Motor proteins require which of the following to function in the movement of chromosomes toward the poles of the mitotic spindle? (A) intact centromeres (B) a microtubule-organizing center (C) ATP as an energy source (D) synthesis of cohesin

13. A female with a paternal set of one orange and one long gene chromosome and a maternal set comprised of one blue and one short gene chromosome is expected to produce which of the following types of eggs after meiosis? (A) All eggs will have maternal types of gene combinations. (B) All eggs will have paternal types of gene combinations. (C) Half the eggs will have maternal and half will have paternal combinations. (D) Each egg has a one-fourth chance of having either blue long, blue short, orange long, or orange short combinations.

14. Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division? (A) prophase I of meiosis (B) anaphase II of meiosis (C) metaphase II of meiosis (D) anaphase I of meiosis

15. Cinnabar eyes is a sex-linked, recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F1 males will have cinnabar eyes? (A) 0% (B) 25% (C) 50% (D) 100%

17. An original section of DNA has the base sequence AGCGTTACCGT. A mutation in this DNA strand results in the base sequence AGGCGTTACCGT. This change represents  ________.(A) a missense mutation (B) a point mutation (C) a silent mutation (D) frameshift mutation

18. Imagine that you've isolated a yeast mutant that contains histones resistant to acetylation. What phenotype do you predict for this mutant? (A) The mutant will grow rapidly. (B) The mutant will require galactose for growth. (C) The mutant will show low levels of gene expression. (D) The mutant will show high levels of gene expression.

19. Which of the following human diseases is caused by a virus that requires reverse transcriptase to transcribe its genome inside the host cell? (A) herpes (B) AIDS (C) smallpox (D) influenza

20. A laboratory might use dideoxyribonucleotides to  ________.(A) separate DNA fragments (B) produce cDNA from mRNA (C) sequence a DNA fragment (D) visualize DNA expression

21. When gene duplication occurs to its ultimate extent by doubling all genes in a genome, what has occurred? (A) pseudogene creation (B) creation of a gene cluster (C) creation of a polyploid (D) creation of a diploid

22. A farmer uses triazine herbicide to control pigweed in his field. For the first few years, the triazine works well and almost all the pigweed dies； but after several years, the farmer sees more and more pigweed. Which of these explanations best explains what happened? (A) The herbicide company lost its triazine formula and started selling poor-quality triazine. (B) Natural selection caused the pigweed to mutate, creating a new triazine-resistant species. (C) Triazine-resistant pigweed has less-efficient photosynthesis metabolism. (D) Triazine-resistant weeds were more likely to survive and reproduce.