The TAS2RIS gene cocodes a recesor rtn thur inuncrs the shitary to sane ben. The ae ha ei a dominant, wildcype atele that emables n jodividal (tater to tate bieresnda reevt ele that interferes with the tity of in indoidul otastero tae hittemes. Theee single lotide cong replon of the TASZRis pre e sociaed wth the notate allele. The macleotides pert theee positions e shown in the table below NUCLEOTIDE VARIATION IN THE TASZRS GENE Position in the Nucletide Sequence 145 785 Muman nontaster G. Human taiter Bonobo Chimpantee G. Gorilla A cladngrani representing the evilutionary relatednes of selected primates is sbown belew. Orangutan Corilla Chimpanzee Bonobo Human 39. The TAS2R38 receptor protein has been deu on the surface of cells from individuals who homozygous for the nootaster allele of the TASZRIS gene. Which of the following is the most likely effect of the mutations associated w the nontaster allele on TASZR3S gene expression (A) The mutations change the primary structure of the encoded receptor protein. (B) The mutations increase the stability of the TAS2R38 MRNA (C) The mutations prevent transcription of the TAS2RI8 gene. (D) The mutations prevent translation of the TAS2R38 MRNA. 36. In a sample of 2.400 people, 1,482 were found to have the dominant (taster phenotype. Assuming that the popalation is in Hardy-Weinberg equilibeium, appeoximately how many individuals in the sample are expected to be heterozygous for TASZRIS (A) 741 (B) 918 (C) L133 (D) 1,482 37. Which of the fellowing scientifie questions will best help researchers determine when the nootaster alele arose in the evolutionary history of the selected primates? 40. Toxic substances often have a bitter taste that (A) How does the nontaster allele contribute to individual fitness? (8) Does the nontaster allele exist in any nonhuman primate populations? (C) What caused the mutations in the TAS2RIS gene? (D) How do the mutations in the nontaster allele affect the stracture of the resulting protein? causes animals who try to eat such substances to spit them out rather than swallow them, Additional data suggest that gorilla populations have a very low frequency of nontasters. Which of the following best describes the likely evolution of the TASZR38 locus in the gorilla population? (A) Gorillas who could taste bitter toxins were more likely to survive and reproduce than nontasters (B) Gorillas who could taste bitter toxins became resistant to the toxins, so the taster gene was no longer under selective pressure. (C) Gorillas acquired the taster allele by horizontal gene transfer from chimpanzees. (D) Gorillas who could taste bitter toxins could utilize food resources that nontasters could not. 38. Which of the following conclusions is supported by the data? (A) Humans and booobos belong to the same genus because the ouclectide sequence of the TASZRI8 gene is the same, (8) Chimpanzees are equally related to humans and bonobos because all three groups possess variants of the TAS2R38 gene (C) Humans are more closely related to bonobos than to chimpanzees because the branch of the tree with humans is elosest to the branch of the tree with bonobos. (D) Bonobos are more closely related to humans than to gorillas because bonobos and humans share a more recent common ancestor than bonobos and gorillas do.