GENETICS; A CONCEPTUAL APPROACH BY JUNG H. CHOI MARK E MC CALLUM 6TH EDITION MANUAL WITH SOLVED PROBLEMS 2023/2024

Chapter One: Introduction to Genetics COMPREHENSION QUESTIONS Section 1.1 *1. How did Hopi culture contribute to the high incidence of albinism among members of the Hopi tribe? Solution: In 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. Because the male albinos remained in the village during the day, they had mating advantages over the males who participated in farming and other duties outside of the village. Albinism was considered to be a positive trait reflecting the purity of the villagers. Finally, the small population size of the Hopi tribe may have helped increase the allele frequency of the albino gene due to chance. 2. Outline some of the ways in which genetics is important to all of us. Solution: Genetics directly influences our lives and is fundamental to what and who we are. For example, genes affect our appearance (e.g., eye color, height, weight, skin pigmentation, and hair color). Our susceptibility to diseases and disorders is affected by our genetic makeup. Genetics plays a significant role in researching and developing techniques to diagnose and treat these hereditary diseases. Genes may also influence our intelligence and personality. Genetic techniques have enabled scientists to develop genetically modified crops that are resistant to pesticides and herbicides or that have enhanced nutritional properties making it possible to produce larger quantities of food for the world’s growing population. Lastly, genetic engineering has made it possible to mass produce pharmaceuticals and other substances of commercial value. 3. 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. 4. Briefly explain why genetics is crucial to modern biology. Chapter One: Introduction to Genetics 2 Solution: Genetics is crucial to modern biology in that it provides unifying principles: The genetic code is universal, meaning that 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. 5. List the three traditional subdisciplines of genetics and summarize what each covers. Solution: 1) Transmission (classical) genetics is concerned with the inheritance of genes from one generation to the next. It also deals with the location of genes on chromosomes and gene- mapping. 2) Molecular genetics focuses on the structure, organization, and function of genes at the molecular level. Molecular genetics is also concerned with the processes by which genetic information is transferred and expressed. 3) Population genetics studies genetic variation and changes in genes and allele frequencies within groups of individuals of the same species over time. 6. What are some characteristics of model genetic organisms that make them useful for genetic studies? Solution: 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 7. 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. 8. Outline the notion of pangenesis and explain how it differs from the germ-plasm theory. Chapter One: Introduction to Genetics 3 Solution: Pangenesis theorizes that information for creating each part of the offspring’s body originates from each respective 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 (eggs and sperm) possess all of the information required to make the complete body; the rest of the body contributes no information to the next generation. 9. What does the concept of the inheritance of acquired characteristics propose and how is it related to the concept 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, according to the theory of inheritance of acquired characteristics, the development of large bicep muscles through exercise would produce children with large biceps. 10. 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 that is 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. 11. Define blending inheritance and contrast it with preformationism. Solution: The theory of blending inheritance proposes that the egg and sperm from two parents contains 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. 12. How did developments in botany in the seventeenth and eighteenth centuries contribute to the rise of modern genetics? Solution: Botanists of the seventeenth and eighteenth centuries discovered that plants reproduce sexually, enabling them to develop 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. 13. List some advances in genetics made in the twentieth century