SOLVED

21. If the parents are AO and BO genotypes for the ABO blood group, their children could include which of the following genotypes? A. AO and BO only B. AO, BO, and AB only C. AA, BB, and AB only D. AO, BO, and OO only E. AO, BO, AB, and OO only 22. Haiti is settled by peoples of both African and European ancestry. A young couple, both with mixed ancestry, marry and have several children. The children vary widely in the amount of skin melanin production, with one child being lighter than both parents, and one being darker. The simple explanation for this is A. epistasis. B. multiple alleles are available for the one chromosomal locus that governs skin color. C. the environment affected the phenotype that developed. D. polygenic inheritance. E. gene linkage. 23. Lethal genes (genes that result in the failure to develop a vital organ or metabolic pathway) are nearly always recessive. Animal breeders who discover a unique trait and selectively breed to increase the occurrence of that trait often encounter a noticeable increase in lethal genes. Why? A. The lethal recessive gene may be incompletely dominant. B. Spreading the gene among offspring of both sexes will increase the likelihood it will be sex-linked and expressed. C. The selective-mating of closely related individuals, or inbreeding, increases chances that two recessive genes will “meet” in offspring. D. “Pleiotropy” – the gene that is being selected for this trait may have the second effect of being lethal. E. “Epistasis” – selection for the desired trait may result in “uncovering” the lethal gene. 24. Unattached earlobes (EE or Ee) are described in the textbook as dominant over attached earlobes (ee). A couple both have unattached earlobes. Both notice that one of their parents on both sides has attached earlobes (ee). Therefore, they correctly assume that they are carriers for attached earlobes (Ee). The couple proceeds to have four children. A. They can be certain that three will be heterozygous and one homozygous recessive. B. If the first three are heterozygous, the fourth must be homozygous recessive. C. The children must repeat the grandparents’ genotype (Ee). D. All children must have unattached earlobes since both parents possess the dominant gene for it. E. Two heterozygous, one homozygous recessive and one homozygous dominant is a likely outcome, but all heterozygous, or two, three or all four homozygous are also possible. 25. In 1940, two researchers named Weiner and Landsteiner discovered that about 85 percent of the human population sampled possessed a blood cell protein that had been previously detected in Rhesus monkeys. This blood type was labeled Rh positive, and Rh+ was found to be dominant over the absence of the blood factor (Rh). Under normal Mendelian inheritance, which of the following statements is FALSE? A. Two Rh+ parents could have an Rh- child. B. Two Rh- parents could have an Rh+ child. C. An Rh- child would require that both parents be carriers of at least one Rh- gene. D. It is possible with just one pair of parents to have children where some siblings are Rh- and some are Rh+. E. All of the choices are false. Â Â