Chapter 24 Genetics of Behavior1) Autism spectrum disorders are neurodevelopmental disorders that appear to be ________.A) caused by a single dominant geneB) multifactorial and complex in nature with a genetic componentC) caused by several genes located on the X chromosomeD) caused by a low number of recessive genes located mainly on the autosomesE) directly related to trinucleotide repeat increases but not decreasesAnswer: BSection: 24.32) Recent research using gene expression profiles indicates that schizophrenia and autism spectrum disorders are ________.A) like opposite sides of the same coinB) identical at the molecular levelC) completely unrelatedD) likely to be caused by the same dominant geneE) likely to be caused by the same recessive geneAnswer: ASection: 24.33) What conclusion has been reached regarding the genetic status of schizophrenia using genome-wide association studies?A) A single dominant gene is involved.B) No single gene or allele makes a significant contribution.C) A single recessive gene is involved.D) Several dominant genes located on the X chromosome cause this disease.E) No more than three loci are involved in the expression of schizophrenia.Answer: BSection: 24.34) What is a major problem that arises in the study of the genetic basis of human behavior?A) Memories of individuals are unreliable.B) People are too short lived.C) Behaviors are difficult to define objectively.D) The environment plays no role in behavioral expression.E) The environment is the only factor that determines human behavior.Answer: CSection: 24.31Copyright © 2012 Pearson Education, Inc.5) One of the oldest recorded behavior mutants is the waltzer mutation in the mouse. Mutant mice can be observed "dancing" and "head shaking"; some are also deaf. Mice must be homozygous for a mutation to express the trait. Based on this information, the genetic cause of this trait is most likely a(n) ________.A) simple recessive pattern of inheritanceB) multifactor, polygenic pattern of inheritanceC) dominant/recessive pattern typical of other behavioral traitsD) epistatic pattern with incomplete dominanceE) variable gene activity pattern with overdominance causing deafnessAnswer: ASection: 24.16) Humans are relatively unavailable as experimental subjects in genetic investigations, yet considerable interest surrounds intelligence, language, personality, and emotional behaviors. Onedifficulty in studying such behaviors is the high likelihood that they ________.A) are strongly influenced by birth order and dietB) are affected by the environmentC) follow non-Mendelian patterns of inheritanceD) follow extranuclear patterns of inheritanceE) have no likely genetic influenceAnswer: BSection: 24.37) Huntington disease (HD) is a well-studied, autosomal dominant disorder that affects the nervous system. Symptoms usually appear after age 40, and victims usually die within 10 to 15 years after onset of the disease. It appears that at least in some cases of HD, "stutter" mutations occur. Such mutations are characterized by ________.A) uncontrolled verbal capacity of patientsB) extra trinucleotide repeats within the HD geneC) RNA polymerase imperfections leading to altered DNAsD) repeated DNA polymerases generating too many coding symbolsE) links between monoamine oxidase A (MAOA) and hexokinaseAnswer: BSection: 24.38) Present an overview of the research dealing with the genetics of behavior in small mammals (mice or rats) and Drosophila.Answer: mice or rats: fear and anxiety, Huntington disease; Drosophila: geo- and phototaxis andsingle gene influences such as those relating to courtship and mating, learning and memorySection: 24.1, 24.29) Much effort has been expended to understand genetic involvement in brain function in Drosophila. Why might this research be important in understanding the functioning of the humanbrain?Answer: Mammalian homologs of the Drosophila genes are active in parts of mammalian brains.Section: 24.22Copyright © 2012 Pearson Education, Inc.10) How would the use of a large series of monozygotic and dizygotic twins enhance studies on the genetic basis of human behavior?Answer: Monozygotic twins are genetically identical, and when reared under the same versus different environments, one can estimate the degree to which variation in behavior is determined by heredity. Dizygotic twins are genetically different, but by having the same intrauterine and developing environment (if being reared in the same household), one can again estimate the influence of heredity on behavioral traits.Section: 24.311) Why is cyclic AMP considered important in behavioral studies?Answer: Cyclic AMP affects short-term memory using the potassium channel in the plasma membrane and affects long-term memory by regulating the transcription factor CREB.Section: 34.212) Describe what is meant by the nature-nurture controversy.Answer: Among complex organisms, it is often difficult to determine the roles of the environment and genes in determining certain traits, especially behavioral traits.Section: Introduction13) Describe three general approaches used in the study of the genetics of behavior.Answer: determination of behavioral differences between genetic strains of closely related organisms, selection of strains, study of single gene effectsSection: 24.1, 24.214) Some behavioral studies have been carried out on E. coli, a bacterium. In what way might welearn about the complex behaviors of "higher" organisms by a study of behavior in E. coli?Answer: Certain behaviors, such as chemotactic responses in E. coli, involve a number of gene products that process stimuli and generate responses through metabolic networks that involve protein phosphorylation. Such studies represent the most well-studied relationship between behavior and metabolism.Section: 24.215) List at least three areas of research that deal with the genetics of behavior in humans.Answer: Huntington disease, schizophrenia, autismSection: 24.316) The movement of a free-living organism toward or away from the source of an external stimulus is called ________.Answer: taxisSection: 24.117) List two problems with determining the genetic basis of a behavioral trait in humans.Answer: influence of the environment and difficulty in conducting genetic studies on humansSection: 24.33Copyright © 2012 Pearson Education, Inc.18) Determining the genetic influence on two fairly common human behavioral disorders has eluded researchers for