SOLUTIONS AND PROBLEM SOLVING MANUAL FOR GENETICS ESSENTIALS CONCEPTS AND CONNECTIONS THIRD EDITION By PIERCES TEST BANK

1. How did the Hopi culture contribute to the high incidence of albinism among members of the Hopi tribe? Solution: In the Hopi culture, albino individuals were considered special and awarded special status in the village. Hopi male albinos were not required to work the fields, thus avoiding extensive exposure to sunlight that could prove damaging or deadly. Albinism was considered a positive trait and not a negative physical condition, which allowed albinos to have more children, increasing the frequency of the albino allele. Finally, the small population size of the Hopi tribe may have helped increase the allele frequency of the albino gene due to chance. 2. Give at least three examples of the role of genetics in society today. Solution: Genetics plays important roles in the diagnosis and treatment of hereditary diseases; in breeding plants and animals for improved production and disease resistance; and in producing pharmaceuticals and novel crops through genetic engineering. 3. Briefly explain why genetics is crucial to modern biology. Solution: Genetics is crucial to modern biology in that it provides unifying principles: all organisms use nucleic acid as their genetic material, and all organisms encode genetic information in the same manner. The study of many other biological disciplines, such as developmental biology, ecology, and evolutionary biology, is supported by genetics. 4. List the three traditional subdisciplines of genetics and summarize what each covers. Solution: Transmission genetics: inheritance of genes from one generation to the next, gene- mapping Molecular genetics: structure, organization, and function of genes at a molecular level. Population genetics: the genetic composition of populations and how the genetic composition changes over time. 5. What are some characteristics of model genetic organisms that make them useful for genetic studies? Solution: 2 Chapter One: Introduction to Genetics Model genetic organisms have relatively short generation times, produce numerous progeny, are amenable to laboratory manipulations, and can be maintained and propagated inexpensively. Section 1.2 6. When and where did agriculture first arise? What role did genetics play in the development of the first domesticated plants and animals? Solution: Agriculture first arose 10,000 to 12,000 years ago in the area now referred to as the Middle East (i.e., Turkey, Iran, Iraq, Syria, Jordan, and Israel). Early farmers selectively bred individual wild plants or animals that had useful characteristics with others that had similar useful traits. The farmers then selected for offspring that contained those useful features. Early farmers did not completely understand genetics, but they clearly understood that breeding individual plants or animals with desirable traits would lead to offspring that contained these same traits. This selective breeding led to the development of domesticated plants and animals. 7. Outline the concept of pangenesis and explain how it differs from the germ-plasm theory. Solution: Pangenesis theorizes that information for creating each part of the offspring’s body originates from each part of the parent’s body and is passed through the reproductive organs to the embryo at conception. Pangenesis suggests that changes in parts of the parent’s body may be passed to the offspring’s body. The germ-plasm theory, in contrast, states that the reproductive cells possess all of the information required to make the complete body; the rest of the body contributes no information to the next generation. 8. What does the concept of the inheritance of acquired characteristics propose and how is it related to the notion of pangenesis? Solution: The theory of inheritance of acquired characteristics postulates that traits acquired during one’s lifetime can be transmitted to offspring. It developed from pangenesis, which postulates that information from all parts of one’s body is transmitted to the next generation. Thus, for example, learning acquired in the brain or larger arm muscles developed through exercise could be transmitted to offspring. 9. What is preformationism? What did it have to say about how traits are inherited? Solution: Preformationism is the theory that the offspring results from a miniature adult form already preformed in the sperm or the egg. All traits would thus be inherited from only one parent, either the father or the mother, depending on whether the homunculus (the preformed miniature adult) resided in the sperm or the egg. Chapter One: Introduction to Genetics 3 10. Define blending inheritance and contrast it with preformationism. Solution: The theory of blending inheritance proposes that the egg and sperm from two parents contain material that blends upon conception, influencing the development of the offspring. This theory indicates that the offspring is an equal blend of the two parents. In preformationism, the offspring inherits all of its traits from one parent. 11. How did developments in botany during the seventeenth and eighteenth centuries contribute to the rise of modern genetics? Solution: Botanists of the seventeenth and eighteenth centuries developed new techniques for crossing plants and creating plant hybrids. These early experiments provided essential background work for Mendel’s plant crosses. Mendel’s work laid the foundation for the study of modern genetics. 12. List some advances in genetics made in the twentieth century. Solution: 1902 Proposal that genes are located on chromosomes by Walter Sutton 1910 Discovery of the first genetic mutation in a fruit fly by Thomas Hunt Morgan 1930 The foundation of population genetics by Ronald A. Fisher, John B. S. Haldane, and Sewall Wright 1940s The use of viral and bacterial genetic systems 1953 Three-dimensional structure of DNA described by Watson and Crick 1966 Deciphering of the genetic code 1973 Recombinant DNA experiments 1977 Chemical and enzymatic methods for DNA sequencing developed by Walter Gilbert and Frederick Sanger 1986 PCR developed by Kary Mullis 1990 Gene therapy 13. Briefly explain the contribution that each of the following persons made to the study of genetics. Solution: a. Matthias Schleiden and Theodor Schwann Proposed the concept of the cell theory, which indicated that the cell is the fundamental unit of living organisms. Caused biologists interested in heredity to examine cell reproduction. b. August Weismann Proposed the germ-plasm theory, which holds that cells in reproductive organs carry a complete set of genetic information. d. Gregor Mendel 4 Chapter One: Introduction to Genetics First discovered the basic rules of inheritance. e. James Watson and Francis Crick Along with Roslind Franklin and Maurice Wilkins, described the three-dimensional structure of DNA. f. Kary Mullis Developed the polymerase chain reaction, used to quickly amplify small amounts of DNA. Section 1.3 14. What are the two basic cell types (from a structural perspective) and how do they differ? Solution: The two basic cell types are prokaryotic and eukaryotic. Prokaryotic cells do not have a nucleus, and their chromosomes are found within the cytoplasm. They do not possess membrane-bound cell organelles. Eukaryotic cells possess a nucleus and membrane-bound cell organelles. *15. Summarize the relations between genes, DNA, and chromosomes. Solution: Genes are composed of DNA nucleotide sequences that are located at specific positions in chromosomes.