Ibsen: Oral Pathology for the Dental Hygienist, 7th Edition Chapter 06: Genetics

Which statement is correct concerning chromosomes? a. Chromosomes are located in the nucleus of the cell. b. Mature germ cells (ova and spermatozoa) contain 46 chromosomes. c. Chromosomes can only be seen clearly under a microscope when the nucleus and cell are dividing. d. Chromosomes contain RNA, which directs the production of amino acids, polypeptides, and proteins by the cell. Answer- b The gap 2 (G2) phase of mitosis a. begins when mitotic division ends. b. ends when mitotic division begins. c. precedes the S phase. d. is when replication of DNA takes place. Answer- b The correct order for the stages of mitosis is a. prophase, anaphase, metaphase, telophase. b. prophase, metaphase, anaphase, telophase. c. prophase, metaphase, telophase, anaphase. d. metaphase, prophase, telophase, anaphase. Answer- d Primitive germ cells have _____ chromosomes and are termed _____. a. 23; diploid b. 46; haploid c. 23; haploid d. 46; diploid Answer- c Points of contact between the chromatid of one chromosome and the chromatid of the other chromosome of a pair, where crossing over and exchange of chromosome segments occur are termed a. First meiosis. b. Second meiosis. c. chiasmata. d. interpolation. Answer- b After metaphase of the first meiotic division a. the chromosomes split at the centromere and separate from one another. b. the chromosomes do not split at the centromere but separate from one another. c. each member of the pair migrates to one of the new cells, each of which contains 46 chromosomes but twice the final amount of DNA. d. each member of the pair migrates to one of the new cells, each of which contains 23 chromosomes but half the final amount of DNA. Answer- d Which statement is true of oogenesis? a. Oogenesis starts around the time of puberty. b. The second meiosis is completed at the beginning of ovulation. c. Nondisjunction is more prevalent in male spermatogenesis than in female oogenesis. d. The older the woman, the greater the chance of shedding a trisomic ovum. Answer- b