TEST BANK Genetics Essentials: Concepts and Connections 5th Edition by Benjamin A. Pierce 2025

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Chapter 01: Introduction to Genetics 1. Albinism is rare in most human populations, occurring at a frequency of about 1 in 20,000 people. However, the trait occurs at a frequency of 1 in 200 in certa... in Hopi villages of Black Mesa in Arizona. Explain in terms of natural selection why albinism is so rare in most human populations. ANSWER: In most populations, there is fairly strong selection against albinism because albinos don’t produce melanin, causing their skin cells not to be protected from the damaging effects of sunlight. Also, the lack of melanin in their eyes causes them to have poor eyesight. Finally, in most cultures albinos are seen as abnormal, and they are not normally sought out for marriage and mating. Therefore, in most populations the alleles that cause albinism are selected against, and they decrease in frequency or are kept at a low level, causing the recessive trait to be rare. 2. Albinism is rare in most human populations, occurring at a frequency of about 1 in 20,000 people. However, the trait occurs at a frequency of 1 in 200 in certain Hopi villages of Black Mesa in Arizona. Explain in terms of natural selection why the trait is so much more common among the Hopis of Black Mesa. ANSWER: Albinos occupy a privileged position among the Hopis of Black Mesa. In this culture, albinos are viewed as especially pretty, clean, and intelligent, and they often occupy positions of leadership. Albinos are celebrated in the villages as a sign of purity of Hopi blood in the community. Furthermore, albinos are often excused from normal male field labor because of their sensitivity to sunlight, causing them to be left behind in the village with the women during the daytime. This allows them extra mating opportunities compared to the other men of the village. Therefore, the alleles that cause albinism are either selected for in this culture or at least not selected against as strongly as in other cultures, allowing the trait to occur at a much higher frequency. 3. Which one of the following pairings between the subdiscipline of genetics and the phenomenon is INCORRECT? a. evolution—population genetics b. gene regulation—molecular genetics c. allelic frequency alteration—population genetics d. arrangement of genes on chromosome—transmission genetics e. chemical nature of the gene—transmission genetics ANSWER: e 4. Which one of the following topics of research belongs to the discipline of transmission genetics? a. inheritance pattern of gene alleles b. mechanism of DNA replication c. gene expression patterns d. evolution e. chemical modification of nucleic acids ANSWER: a 5. The complete genetic makeup of an organism is referred to as its a. chromosome. b. alleles. c. locus. d. genome. e. phenotype. ANSWER: d 6. Identify a TRUE statement from the following descriptions concerning genetics. a. The theory of pangenesis states that all living organisms are composed of cells. b. Bacteria and viruses are not useful in studying genes and inheritance because they are structurally and metabolically different from eukaryotic cells. c. Charles Darwin accurately described the laws of inheritance in his landmark book, On the Origin of Species. d. Many human traits, such as skin and hair color, are determined by more than a single gene. e. Evolution can occur without genetic changes in the population. ANSWER: d 7. Identify a FALSE statement from the following descriptions of genetics. a. Humans first applied genetics to the domestication of plants and animals between approximately 10,000 and 12,000 years ago. b. Some viruses use RNA to carry their genetic information. c. Albinism results from a mutation in the genes that control the synthesis and storage of melanin. d. All human traits that display blending inheritance are affected by a single gene. e. The process by which genetic information is copied and decoded is similar for all forms of life. ANSWER: d 8. Which of the following species is considered a model genetic organism? a. the plant Linaria vulgaris b. the deer mouse Peromyscus maniculatus c. the worm Caenorhabditis elegans d. the frog Hyla chrysoscelis e. the chimpanzee Pan troglodytes ANSWER: c 9. Which of the following would serve the LEAST well as a model for understanding basic mechanisms of inheritance? a. fruit flies b. humans c. yeast d. mice e. zebrafish ANSWER: b 10. Which of the following statements is TRUE? a. Each subdiscipline of genetics is very specific as to what is explored and does not overlap with the other subdisciplines. b. All phenotypes or traits are always determined by multiple genes. c. Albinism arises from the overexpression of the gene that controls the synthesis and storage of melanin. d. Humans make excellent model organisms because they have a variety of well-defined traits. e. None of the statements provided are true. ANSWER: e 11. Which of the following statements is CORRECT? a. All genomes are encoded in DNA only. b. All genomes are encoded in nucleic acids. c. All genomes are encoded in proteins only. d. The genetic instructions are decoded completely differently in each organism. e. Molecular studies suggest life evolved from multiple primordial ancestors. ANSWER: b 12. Which of the following traits would make a species useful as a model genetic organism? (Select all that apply.) a. large number of progeny b. long generation time c. small size d. ability to be studied in a laboratory e. ability to be propagated inexpensively ANSWER: a, c, d, e 13. Which one of the following topics belongs to a different subdiscipline of genetics when compared with the rest? a. mechanism of gene regulation b. allele frequencies of a certain gene in different environments c. transcription d. chemical alternation of chromosomes e. mechanism of DNA replication ANSWER: b 14. The fruit fly Drosophila melanogaster is an important model system for studying inheritance in animals and genetic control of animal development, including humans. If researchers ultimately want to understand a biological process in humans, why might they want to study the process in fruit flies first? (Select all that apply.) a. Fruit flies are relatively easy to genetically manipulate and to isolate mutations. b. Fruit flies have short generation times and produce relatively large numbers of progeny. c. Fruit flies have simpler genomes than do humans. d. Fruit flies share all important physiolog [Show More]

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