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Concepts of Genetics, 11th Edition Test Bank

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    Concepts of Genetics, 11e, Global Edition (Klug et al.) Chapter 1 Introduction to Genetics 1) In the 1600s, William Harvey studied reproduction and development. What is the term given to the theory which states that an organism develops from the fertilized egg by a succession of developmental events that lead to an adult? A) preformation B) sequential pattern formation C) equational transformation D) transduction E) epigenesis Answer: E Section: 1.1 2) What is the term given to the theory which states that the fertilized egg contains a complete miniature adult? A) preformation B) transduction C) transformation D) conjugation E) cell theory Answer: A Section: 1.1 3) What is the term given to the theory that put forth the idea that living organisms could arise by incubating nonliving components? A) spontaneous generation B) natural selection C) evolution D) preformation E) collective combination Answer: A Section: 1.1 4) Who, along with Alfred Wallace, formulated the theory of natural selection? A) Gregor Mendel B) William Harvey C) Louis Pasteur D) Charles Darwin E) James Watson Answer: D Section: 1.1 1

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    5) Who was the Augustinian monk that conducted a decade of experiments on the garden pea, eventually showing that traits are passed from parents to offspring in predictable ways? A) Francis Crick B) Alfred Wallace C) Hippocrates D) Aristotle E) Gregor Mendel Answer: E Section: 1.2 6) In many species, there are two representatives of each chromosome. In such species, the characteristic number of chromosomes is called the ________ number. It is usually symbolized as ________. A) haploid; n B) haploid; 2n C) diploid; 2n D) diploid; n E) None of the answers listed are correct. Answer: C Section: 1.2 7) Genetics is the study of ________. A) inheritance and variation B) mutation and recession C) transcription and translation D) diploid and haploid E) replication and recombination Answer: A Section: 1.2 8) Name one of the botanists who, in 1900, rediscovered the work of Gregor Mendel. Answer: Carl Correns, Hugo de Vries, Erich Tschermak Section: 1.1 9) Early in the twentieth century, Walter Sutton and Theodor Boveri noted that the behavior of chromosomes during meiosis is identical to the behavior of genes during gamete formation. They proposed that genes are carried on chromosomes, which led to the basis of the ________. Answer: Chromosome Theory of Inheritance Section: 1.2 10) What is a mutation? Answer: A mutation is an inherited change in a gene. Section: 1.2 11) What is a simple definition of an allele? Answer: An allele is a variant form of a gene. Section: 1.2 2

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    12) Until the mid-1940s, many scientists considered proteins to be the likely candidates for the genetic material. Why? Answer: Proteins are the most abundant, universally distributed components in cells. They were considered likely candidates because of their great structural and functional diversity. Section: 1.2 13) Name the individual who, while working with the garden pea in the mid-1850s, demonstrated quantitative patterns of heredity and developed a theory involving the behavior of hereditary factors. Answer: Gregor Mendel Section: 1.2 14) What does the term genetics mean? Answer: Genetics is a subdiscipline of biology concerned with the study of heredity and variation at the molecular, cellular, developmental, organismal, and populational levels. Section: 1.2 15) Name two individuals who provided the conceptual basis for our present understanding that genes are on chromosomes. Answer: Walter Sutton and Theodor Boveri Section: 1.2 16) What term is used to describe the fact that different genes in an organism often provide differences in observable features? Answer: phenotype Section: 1.2 17) What term refers to the similarity between parents and offspring and what term refers to the lack of similarity between parents and offspring? Answer: Heredity refers to the similarity between parents and offspring and the similarity of members of the same species. Variation refers to the lack of similarity between parents and offspring and members of the same species. Section: 1.2 18) Alternative forms of a gene are called ________. Answer: alleles Section: 1.2 19) The various characteristics of organisms that result from their genetic makeup are collectively referred to as an organism's ________. Answer: phenotype Section: 1.2 20) Name the substance that serves as the hereditary material in eukaryotes and prokaryotes. Answer: DNA or deoxyribonucleic acid Section: 1.3 21) In nonviral systems, what is the nature of the hereditary substance? Answer: DNA (deoxyribonucleic acid) is a double-stranded polymer organized as a double helix. Section: 1.3 3

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    22) A fundamental property of DNA's nitrogenous bases that is necessary for the double-stranded nature of its structure is ________. Answer: complementarity Section: 1.3 23) Distinguish the functions of DNA and RNA in a eukaryote. Answer: DNA is responsible for the storage and replication of genetic information; RNA is involved in the expression of stored genetic information. Section: 1.3 24) Name the bases in DNA and their pairing specificities. Answer: adenine:thymine, guanine:cytosine Section: 1.3 25) What is meant by the term genetic code ? Answer: The genetic code consists of a linear series of three adjacent nucleotides present in mRNA molecules. Section: 1.3 26) List the two relatively complex processes in which genetic information is converted into functional products. Answer: transcription and translation Section: 1.3 27) What is the composition of the genetic material? Answer: polymers of nucleotides making up DNA Section: 1.3 28) What is meant by complementarity in terms of the structure of DNA? Answer: base pairing of A with T, and G with C Section: 1.3 29) Reference is often made to adapter molecules when describing protein synthesis in that they allow amino acids to associate with nucleic acids. To what class of molecules does this term refer? Answer: tRNA Section: 1.3 30) Given that DNA is the genetic material in prokaryotes and eukaryotes, what other general structures (macromolecules) and substances made by the cell are associated with the expression of that genetic material? Answer: RNA (messenger, ribosomal, transfer), ribosomes, enzymes, proteins Section: 1.3 31) What is another term for a biological catalyst? Answer: enzyme Section: 1.3 4

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    32) Research dealing with which human blood disorder was instrumental in linking the genotype to a specific phenotype, and what conclusion was reached? Answer: The work on sickle-cell anemia was instrumental in showing that a mutant gene produced a mutant protein molecule. Section: 1.3 33) Recombinant DNA technology is dependent on a particular class of enzymes, known as ________ that cuts DNA at specific nucleotide sequences. Answer: restriction enzymes Section: 1.4 34) What represents an organism's genome? Answer: An organism's genome can be defined as the complete haploid DNA content of an organism. Section: 1.4 35) What is a transgenic organism? Answer: A transgenic organism is an organism produced by biotechnology that involves the transfer of hereditary traits across species. Section: 1.5 36) In 1996, a cloning experiment produced the sheep named Dolly. Contrary to the more traditional method of cloning by embryo splitting, Dolly was produced by which procedure? Answer: transfer of genetic material from an adult mammary cell Section: 1.5 37) What term is applied to a variety of projects whereby genome sequences are deposited in databases for research purposes? Answer: genomics Section: 1.6 38) The human genome sequence was reported in 2003 by two groups, the publicly funded ________ and ________. Answer: Human Genome Project; a private, industry-funded project Section: 1.6 39) A number of genomes have been sequenced in recent years: Escherichia coli, Saccharomyces cerevisiae , Caenorhabditis elegans , Drosophila melanogaster , and Mus musculus . What are the common names for these organisms? Answer: bacterium, yeast, roundworm, fruit fly, mouse Section: 1.7 40) Organisms that are well understood from a scientific standpoint and are often used in basic biological research are often called ________. Answer: model organisms Section: 1.7 41) Arabidopsis is a model organism for the study of ________. Answer: plants Section: 1.7 5

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    42) Genetics is the study of heredity and variation. Answer: TRUE Section: 1.2 43) Complementarity in a genetic sense refers to the polymerization of nucleotides in DNA. Answer: FALSE Section: 1.3 44) Bioinformatics is a discipline involved in the development of both hardware and software for processing, storing, and retrieving nucleotide and protein data. Answer: TRUE Section: 1.6 6

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    Concepts of Genetics, 11e, Global Edition (Klug et al.) Chapter 2 Mitosis and Meiosis 1) Living organisms are categorized into two major groups based on the presence or absence of a nucleus. What group is defined by the presence of a nucleus? A) eukaryotic organism B) virus C) bacterium D) prokaryotic organism E) mitochondrial organism Answer: A Section: 2.1 2) What is the name of the membranous structure that compartmentalizes the cytoplasm of eukaryotic organisms? A) ribosome B) mitochondria C) cytosol D) endoplasmic reticulum E) nucleoid Answer: D Section: 2.1 3) What hypothesis concerns the evolutionary origin of eukaryotic organelles? A) endosymbiont hypothesis B) homologous hypothesis C) analogous hypothesis D) evolutionary hypothesis E) Darwinian hypothesis Answer: A Section: 2.1 4) The diploid chromosome number of an organism is usually represented as 2n. Humans have a diploid chromosome number of 46. What would be the expected haploid chromosome number in a human? A) 92 B) 16 C) 12 D) 24 E) 23 Answer: E Section: 2.2 1

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    5) What significant genetic function occurs in the S phase of the cell cycle? A) cytokinesis B) karyokinesis C) DNA synthesis D) chromosome condensation E) centromere division Answer: C Section: 2.3 6) During interphase of the cell cycle, ________. A) DNA recombines B) sister chromatids move to opposite poles C) the nuclear membrane disappears D) RNA replicates E) DNA content essentially doubles Answer: E Section: 2.3 7) If a typical somatic cell has 64 chromosomes, how many chromosomes are expected in each gamete of that organism? A) 8 B) 16 C) 32 D) 64 E) 128 Answer: C Section: 2.4 8) In an organism with 52 chromosomes, how many bivalents would be expected to form during meiosis? A) 13 B) 26 C) 52 D) 104 E) 208 Answer: B Section: 2.4 2

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    9) The ant, Myrmecia pilosula , is found in Australia and is named bulldog because of its aggressive behavior. It is particularly interesting because it carries all its genetic information in a single pair of chromosomes. In other words, 2n = 2. (Males are haploid and have just one chromosome.) Which of the following figures would most likely represent a correct configuration of chromosomes in a metaphase I cell of a female? A) B) C) D) E) Answer: A Section: 2.4 3

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    10) For the purposes of this question, assume that a G1 somatic cell nucleus in a female Myrmecia pilosula contains 2 picograms of DNA. How much DNA would be expected in a metaphase I cell of a female? A) 16 picograms B) 32 picograms C) 8 picograms D) 4 picograms E) Not enough information is provided to answer the question. Answer: D Section: 2.4 11) Myrmecia pilosula actually consists of several virtually identical, closely related species, with females having chromosome numbers of 18, 20, 32, 48, 60, 62, and 64. Assume one crossed a female of species (A) with 32 chromosomes and a male of species (B) with 9 chromosomes (males are haploid, and each gamete contains the n complement). How many chromosomes would one expect in the body (somatic) cells of the female offspring? A) 4.5 B) 9 C) 25 D) 32 E) 41 Answer: C Section: 2.4 12) What is the outcome of synapsis, a significant event in meiosis? A) side-by-side alignment of nonhomologous chromosomes B) dyad formation C) monad movement to opposite poles D) side-by-side alignment of homologous chromosomes E) chiasma segregation Answer: D Section: 2.4 13) In a healthy female, how many secondary oocytes would be expected to form from 100 primary oocytes? How many first polar bodies would be expected from 100 primary oocytes? A) 200; 50 B) 100; 50 C) 200; 300 D) 100; 100 E) 50; 50 Answer: D Section: 2.5 4

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    14) In a healthy male, how many sperm cells would be expected to be formed from (a) 400 primary spermatocytes? (b) 400 secondary spermatocytes? A) (a) 800; (b) 800 B) (a) 1600; (b) 1600 C) (a) 1600; (b) 800 D) (a) 400; (b) 400 E) (a) 100; (b) 800 Answer: C Section: 2.5 15) Electron microscopy of metaphase chromosomes demonstrated various degrees of coiling. What was the name of the model that depicted this process? A) folded-fiber B) double-stranded C) chromatid folding D) packing E) condensation Answer: A Section: 2.7 16) Name two cellular organelles, each containing genetic material, which are involved in either photosynthesis or respiration. Answer: chloroplasts and mitochondria Section: 2.1 17) The nucleolus organizer (NOR) is responsible for production of what type of cell structure? Answer: ribosome Section: 2.1 18) List four terms used to describe the normal morphologies, with respect to arm ratio, of eukaryotic chromosomes. Answer: metacentric, submetacentric, acrocentric, telocentric Section: 2.2 19) Homologous chromosomes are those that can be matched by virtue of their similar structure and function within a nucleus. Which chromosomes making up a genome do not follow the same characteristics of homology? Answer: sex-determining chromosomes Section: 2.2 20) In which stage of the cell cycle is G0 located? Answer: G1 Section: 2.3 21) When cells withdraw from the continuous cell cycle and enter a "quiescent" phase, they are said to be in what stage? Answer: G0 Section: 2.3 5

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    22) The house fly, Musca domestica , has a haploid chromosome number of 6. How many chromatids should be present in a diploid, somatic, metaphase cell? Answer: 24 Section: 2.3 23) How many haploid sets of chromosomes are present in a diploid individual cell with a chromosome number of 46? 32? Answer: 2; 2 Section: 2.3 24) How many haploid sets of chromosomes are present in an individual cell that is tetraploid (4n) ? Answer: 4 Section: 2.3 25) You may have heard through various media of an animal alleged to be the hybrid of a rabbit and a cat. Given that the cat ( Felis domesticus ) has a diploid chromosome number of 38 and a rabbit ( Oryctolagus cuniculus ) has a diploid chromosome number of 44, what would be the expected chromosome number in the somatic tissues of this alleged hybrid? Answer: 41 Section: 2.3 26) Regarding the mitotic cell cycle, what is meant by a checkpoint? Answer: A checkpoint is the portion of a cell cycle that is sensitive to a variety of conditions that impact the eventual health of the cell or individual. Such checkpoints often restrict passage to the next event in the cell cycle. Section: 2.3 27) Assume that the somatic cells of a male contain one pair of homologous chromosomes (e.g., AaAb), and an additional chromosome without a homolog (e.g., W). What chromosomal combinations would be expected in the meiotic products (spermatids) of a single primary spermatocyte? (There may be more than one answer.) Answer: A a W, A a W, A b , A b or Aa, Aa, AbW, AbW Section: 2.4 28) Trisomy 21, or Down syndrome, occurs when there is a normal diploid chromosomal complement of 46 chromosomes plus one (extra) chromosome #21. Such individuals therefore have 47 chromosomes. Assume that a mating occurs between a female with Down syndrome and a normal 46-chromosome male. What proportion of the offspring would be expected to have Down syndrome? Justify your answer. Answer: One-half of the offspring would be expected to have Down syndrome because of 2 × 1 segregation of chromosome #21 at anaphase I. Section: 2.4 6

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    29) The accompanying sketch depicts a cell from an organism in which 2n = 2 and each chromosome is metacentric. a) Circle the correct stage for the cell in this sketch : anaphase of mitosis anaphase of meiosis I anaphase of meiosis II telophase of mitosis b) Given that each G1 nucleus from this organism contains 16 picograms of DNA, how many picograms of chromosomal DNA would you expect in the cell shown below? Answer: (a) anaphase of meiosis II (b) 16 Section: 2.4 30) The horse ( Equus caballus ) has 32 pairs of chromosomes, whereas the donkey ( Equus asinus ) has 31 pairs of chromosomes. How many chromosomes would be expected in the somatic tissue of a mule? Answer: 63 Section: 2.4 31) Name two evolutionarily significant benefits of meiosis that are not present in mitosis. Answer: reshuffling of homologous chromosomes and crossing over Section: 2.4 32) What is meant by the term chiasma ? Answer: areas where chromatids intertwine during meiosis Section: 2.4 33) After which meiotic stage (meiosis I or II) would one expect monads to be formed? Answer: meiosis II Section: 2.4 34) List in order of occurrence the phases of (a) mitosis and (b) prophase I of meiosis. Answer: (a) prophase, prometaphase, metaphase, anaphase, telophase (b) leptonema, zygonema, pachynema, diplonema, diakinesis Section: 2.4 35) Two terms, reductional and equational , generally refer to which stages of meiosis (I or II)? Answer: meiosis I and meiosis II, respectively Section: 2.4 7

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    36) Normal diploid somatic (body) cells of the mosquito Culex pipiens contain six chromosomes. Assign the symbols A m A p , B m B p , and C m C p to the three homologous chromosomal pairs. The "m" superscript indicates that the homolog is maternally derived; the "p" indicates a paternally derived homolog. Assume that in the genus Culex , the sex chromosomes are morphologically identical. a) For each of the cell types given below, draw and label (with reference to the symbols defined above) an expected chromosomal configuration. Mitotic metaphase Metaphase of meiosis I Metaphase of meiosis II b) The stage at which "sister chromatids go to opposite poles" immediately follows which of the stages listed in (a)? c) Assuming that all nuclear DNA is restricted to chromosomes and that the amount of nuclear DNA essentially doubles during the S phase of interphase, how much nuclear DNA would be present in each cell listed above? Note: Assume that the G1 nucleus of a mosquito cell contains 3.0 × 10-12 grams of DNA. d) Given that the sex of Culex is determined by alleles of one gene, males heterozygous, Mm , and females homozygous, mm , illustrate a labeled chromosomal configuration (involving the symbols A m A p , B m B p , and C m C p and the M locus) in a primary spermatocyte at metaphase. Assume that the M locus is on the A m A p chromosome and that crossing over has not occurred between the M locus and the centromere. Answer: (a) (b) Metaphase of meiosis II and mitotic metaphase (c) 6, 6, 3 8

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    (d) Section: 2.5 9

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    37) Drosophila melanogaster , the fruit fly, has a 2n chromosome number of 8. Assume that you are microscopically examining the mitotic and meiotic cells of this organism. You note that in the female, two chromosomal pairs are metacentric and that two pairs are acrocentric. a) Draw the chromosomal configurations as you would expect to see them at the stages listed: Mitotic metaphase First polar body (metaphase) Primary oocyte (metaphase) Ootid (G1) Secondary oocyte (metaphase) b) Given that the above-mentioned cells are from individuals heterozygous for two independently segregating, autosomal loci, plum eyes and curled wings, place appropriate symbols (of your designation) on chromosomes in the drawings you made in part (A) above. Assume no crossing over, and there may be more than one correct answer in some cases. c) Assuming that a somatic G2 nucleus from one of the individuals in this scenario contains about 8.0 picograms of DNA, how much nuclear DNA would you expect in each of the cells mentioned above? Answer: (a) & (b) (c) 8, 8, 4, 4, 2 Section: 2.5 10

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    38) Down syndrome, or trisomy 21, in humans is caused by an extra copy of the relatively small, acrocentric chromosome #21. Including only chromosome #21, the X chromosome (medium in size and somewhat metacentric), and the Y chromosome (small and acrocentric), draw one possible array of chromosomes in the four sperm cells produced by the complete meiosis of one primary spermatocyte. For the purposes of this question, assume that males with Down syndrome produce normal ratios of sperm cells. (More than one answer is possible.) Answer: Section: 2.5 39) Assume that an organism has a diploid chromosome number of six. Two chromosomal pairs are telocentric, and the other pair is metacentric. Assume that the sex chromosomes are morphologically identical. Draw chromosomes as you would expect them to appear at the following stages: Primary oocyte (metaphase) Secondary spermatocyte (metaphase) First polar body (metaphase) Answer: Section: 2.5 11

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    40) There is about as much nuclear DNA in a primary spermatocyte as in ________ [number] spermatids? Answer: 4 Section: 2.5 41) List, in order of appearance, all the cell types expected to be formed during (a) spermatogenesis and (b) oogenesis. Answer: (a) spermatogonia, primary spermatocyte, secondary spermatocyte, spermatid, spermatozoa (b) oogonium, primary oocyte, secondary oocyte and first polar body, ootid and second polar body Section: 2.5 42) If a typical G1 nucleus is 2n and contains 2C (two complements) of DNA, a prophase I cell is 2n and contains 4C of DNA. Answer: TRUE Section: 2.3 43) S phase is the part of interphase when DNA duplication takes place. Answer: TRUE Section: 2.3 44) The centromere of a chromosome separates during anaphase. Answer: TRUE Section: 2.3 45) A chromosome may contain one or two chromatids in different phases of the mitotic or meiotic cell cycle. Answer: TRUE Section: 2.4 46) If a typical G1 nucleus contains 2C (two complements) of DNA, a gamete that is haploid ( n ) contains 1C of DNA. Answer: TRUE Section: 2.4 47) During meiosis, chromosome number reduction takes place in anaphase II. Answer: FALSE Section: 2.4 48) A bivalent at pachytene contains four chromatids. Answer: TRUE Section: 2.4 49) The meiotic cell cycle involves two cell divisions but only one DNA replication. Answer: TRUE Section: 2.4 50) An organism with a haploid number of 10 will produce 1024 combinations of chromosomes at the end of meiosis. Answer: TRUE Section: 2.4 12

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    51) An organism with a diploid chromosome number of 46 will produce 223 combinations of chromosomes at the end of meiosis. Answer: TRUE Section: 2.4 13

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    Concepts of Genetics, 11e, Global Edition (Klug et al.) Chapter 3 Mendelian Genetics 1) Name the single individual whose work in the mid-1800s contributed to our understanding of the particulate nature of inheritance as well as the basic genetic transmission patterns. With what organism did this person work? A) Gregor Mendel; Pisum sativum B) George Beadle; Neurospora C) Thomas Hunt Morgan; Drosophila D) Calvin Bridges; Drosophila E) Boris Ephrussi; Ephestia Answer: A Section: 3.1 2) A recessive allele in tigers causes the white tiger. If two normally pigmented tigers are mated and produce a white offspring, what percentage of their remaining offspring would be expected to have normal pigmentation? A) 25% B) 50% C) about 66% D) 75% E) about 90% Answer: D Section: 3.2 3) Polydactyly is expressed when an individual has extra fingers and/or toes. Assume that a man with six fingers on each hand and six toes on each foot marries a woman with a normal number of digits. Having extra digits is caused by a dominant allele. The couple has a son with normal hands and feet, but the couple's second child has extra digits. What is the probability that their next child will have polydactyly? A) 1/32 B) 1/8 C) 7/16 D) 1/2 E) 3/4 Answer: D Section: 3.2 4) Tightly curled or wooly hair is caused by a dominant gene in humans. If a heterozygous curly-haired person marries a person with straight hair, what percentage of their offspring would be expected to have straight hair? A) 25% curly B) 50% straight C) 75% curly D) 100% straight E) It is impossible to predict the outcome. Answer: B Section: 3.2 1

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    5) Which types of phenotypic ratios are likely to occur in crosses when dealing with a single gene pair for which all the genotypic combinations are of equal viability? A) 9:3:3:1, 27:9:9:9:3:3:3:1 B) 1:2:1, 3:1 C) 1:4:6:4:1, 1:1:1:1 D) 12:3:1, 9:7 E) 2:3, 1:2 Answer: B Section: 3.2 6) Assume that a black guinea pig crossed with an albino guinea pig produced 5 black offspring. When the albino was crossed with a second black guinea pig, 4 black and 3 albino offspring were produced. What genetic explanation would apply to these data? A) albino = recessive; black = recessive B) albino = dominant; black = incompletely dominant C) albino and black = codominant D) albino = recessive; black = dominant E) None of the answers listed are correct. Answer: D Section: 3.2 7) The fundamental Mendelian process that involves the separation of contrasting genetic elements at the same locus would be called ________. A) segregation B) independent assortment C) continuous variation D) discontinuous variation E) dominance or recessiveness Answer: A Section: 3.2 8) Which types of phenotypic ratios are likely to occur in crosses when dealing with two gene pairs for which all the genotypic combinations are of equal viability? A) 9:3:3:1 B) 1:2:1, 3:1 C) 6:6:2 D) 12:2:2 E) 2:3, 1:2 Answer: A Section: 3.3 2

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    9) Which types of phenotypic ratios are likely to occur in testcrosses when dealing with two gene pairs for which all the genotypic combinations are of equal viability? A) 9:3:3:1, 27:9:9:9:3:3:3:1 B) 1:2:1, 3:1 C) 1:1:1:1 D) 12:3:1, 9:7 E) 2:3, 1:2 Answer: C Section: 3.3 10) Which types of phenotypic ratios are likely to occur in crosses when dealing with three gene pairs for which all the genotypic combinations are of equal viability? A) 27:9:9:9:3:3:3:1 B) 1:2:1, 3:1 C) 1:4:6:4:1, 1:1:1:1 D) 12:3:1, 9:7 E) 2:3, 1:2 Answer: A Section: 3.4 11) According to Charles Darwin and Alfred Wallace, variations followed a more continuous pattern. According to Mendel's model, variation due to dominance-recessive relationships followed a more ___________ form. A) abstract B) smooth C) discontinuous D) normalized E) transferred Answer: C Section: 3.5 12) Which of the following groups of scientists were influential around the year 1900 in setting the stage for our present understanding of transmission genetics? A) Beadle, Tatum, Lederberg B) Watson, Crick, Wilkins, Franklin C) de Vries, Correns, Tschermak, Sutton, Boveri D) Darwin, Mendel, Lamarck E) Hippocrates, Aristotle, Kölreuter Answer: C Section: 3.5 3

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    13) What meiotic process, relative to the number of chromosomes of a given species, accounts for a significant amount of genetic variation in gametes? A) independent assortment of chromosomes B) trivalent formation C) bivalent formation D) pairing of homologous chromosomes E) formation of the meiotic spindle during chromosome segregation Answer: A Section: 3.6 14) The Chi-square test involves a statistical comparison between measured (observed) and predicted (expected) values. One generally determines degrees of freedom as ________. A) the number of categories being compared B) one less than the number of classes being compared C) one more than the number of classes being compared D) ten minus the sum of the two categories E) the sum of the two categories Answer: B Section: 3.8 15) According to Mendel's model, because of the ________ of chromosomes during meiosis, all possible combinations of gametes will be formed in equal frequency. Answer: independent assortment Section: 3.1 16) Assume that in a series of experiments, plants with round seeds were crossed with plants with wrinkled seeds and the following offspring were obtained: 220 round and 180 wrinkled. a) What is the most probable genotype of each parent? b) What genotypic and phenotypic ratios are expected? c) Based on the information provided in part (b), what are the expected (theoretical) numbers of progeny (400 total) of each phenotypic class? Answer: (a) assuming that round ( W ) is dominant to wrinkled ( w ): Ww × ww (b) 1:1 (c) 200 Section: 3.2 17) In peas, gray seed color is dominant to white. For the purposes of this question, assume that Mendel crossed plants with gray seeds with each other and the following progeny were produced: 320 gray and 80 white. a) What is the most probable genotype of each parent? a) What genotypic and phenotypic ratios are expected in the progeny of such a cross? Answer: (a) assuming the following symbols: G = gray and g = white, Gg × Gg (b) genotypic = 1:2:1, phenotypic = 3:1 Section: 3.2 4

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    18) Assume that you have a garden and some pea plants have solid leaves and others have striped leaves. You conduct a series of crosses [(a) through (e)] and obtain the results given in the table. Define gene symbols and give the possible genotypes of the parents of each cross. Answer: (a) From cross (d), assume that solid (S) is dominant to striped (s) : Ss × ss. (b) SS × SS or SS × Ss (c) ss × ss (d) Ss × Ss (e) SS × ss Section: 3.2 19) Albinism, lack of pigmentation in humans, results from an autosomal recessive gene (a) . Two parents with normal pigmentation have an albino child. a) What is the probability that their next child will be albino? b) What is the probability that their next child will be an albino girl? c) What is the probability that their next three children will be albino? Answer: (a) 1/4 (b) 1/4 × 1/2 = 1/8 (c) 1/4 × 1/4 × 1/4 = 1/64 Section: 3.2 20) Dentinogenesis imperfecta is a rare, autosomal, dominantly inherited disease of the teeth that occurs in about one in 8000 people (Witkop 1957). The teeth are somewhat brown in color, and the crowns wear down rapidly. Assume that a male with dentinogenesis imperfecta and no family history of the disease marries a woman with normal teeth. What is the probability that a) their first child will have dentinogenesis imperfecta ? b) their first two children will have dentinogenesis imperfecta ? c) their first child will be a girl with dentinogenesis imperfecta ? Answer: (a) 1/2 (b) 1/2 × 1/2 = 1/4 (c) 1/2 × 1/2 = 1/4 Section: 3.2 21) A certain type of congenital deafness in humans is caused by a rare autosomal (not X-linked) dominant gene. a) In a mating involving a deaf man and a deaf woman (both heterozygous), would you expect all the children to be deaf? Explain your answer. b) In a mating involving a deaf man and a deaf woman (both heterozygous), could all the children have normal hearing? Explain your answer. c) Another form of deafness is caused by a rare autosomal recessive gene. In a mating involving a deaf man and a deaf woman, could some of the children have normal hearing? Explain your answer. Answer: (a) No. In a mating involving heterozygotes, three genotypic classes are expected in the offspring: fully dominant, fully recessive, and heterozygous. (b) Assuming that the parents are heterozygotes (because the gene is rare), it is possible that all of the children could have normal hearing. (c) Since the gene in question is recessive, both of the parents are homozygous and one would not expect normal hearing in the offspring. Section: 3.2 5

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    22) Assuming no crossing over between the gene in question and the centromere, when do alleles segregate during meiosis? Answer: meiosis I, when homologous chromosomes go to opposite poles Section: 3.2 23) Assuming a typical monohybrid cross in which one allele is completely dominant to the other, what ratio is expected if the F 1 s are crossed? Answer: 3:1 Section: 3.2 24) Albinism, lack of pigmentation in humans, results from an autosomal recessive gene (a) . Two parents with normal pigmentation have an albino child. What is the probability that their next child will be albino? Answer: 1/4 Section: 3.2 25) Albinism, lack of pigmentation in humans, results from an autosomal recessive gene (a) . Two parents with normal pigmentation have an albino child. What is the probability that their next child will be an albino girl? Answer: 1/4 × 1/2 = 1/8 Section: 3.2 26) Albinism, lack of pigmentation in humans, results from an autosomal recessive gene (a ). Two parents with normal pigmentation have an albino child. What is the probability that their next three children will be albino? Answer: 1/4 × 1/4 × 1/4 = 1/64 Section: 3.2 27) The autosomal (not X-linked) gene for brachydactyly, short fingers, is dominant to normal finger length. Assume that a female with brachydactyly in the heterozygous condition is married to a man with normal fingers. What is the probability that a) their first child will have brachydactyly? b) their first two children will have brachydactyly? c) their first child will be a brachydactylous girl? Answer: (a) 1/2 (b) 1/2 × 1/2 = 1/4 (c) 1/2 × 1/2 = 1/4 Section: 3.2 28) Tightly curled hair is caused by a dominant autosomal gene in humans. If a heterozygous curly- haired person marries a person with straight hair, what phenotypes (and in what proportions) are expected in the offspring? Answer: 1/2 curly (because the curly-haired individual is most likely heterozygous); 1/2 straight hair Section: 3.2 29) A certain type of congenital deafness in humans is caused by a rare autosomal dominant gene. In a mating involving a deaf man and a deaf woman (both heterozygous), would you expect all the children to be deaf? Explain your answer. Answer: No. In a mating involving heterozygotes, three genotypic classes are expected in the offspring: fully dominant, fully recessive, and heterozygous. Section: 3.2 6

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    30) A certain type of congenital deafness in humans is caused by a rare autosomal dominant gene. In a mating involving a deaf man and a deaf woman, could all the children have normal hearing? Explain your answer. Answer: Assuming that the parents are heterozygotes (because the gene is rare), it is possible that all of the children could have normal hearing. Section: 3.2 31) A certain type of congenital deafness in humans is caused by a rare autosomal recessive gene. In a mating involving a deaf man and a deaf woman, could some of the children have normal hearing? Explain your answer. Answer: Since the gene in question is recessive, both of the parents are homozygous and one would not expect normal hearing in the offspring. Section: 3.2 32) What are two typical testcross ratios? Answer: 1:1 and 1:1:1:1 Section: 3.2 33) The phenotype of vestigial (short) wings (vg) in Drosophila melanogaster is caused by a recessive mutant gene that independently assorts with a recessive gene for hairy (h) body. Assume that a cross is made between a fly with normal wings and a hairy body and a fly with vestigial wings and normal body hair. The wild-type F 1 flies were crossed among each other to produce 1024 offspring. Which phenotypes would you expect among the 1024 offspring, and how many of each phenotype would you expect? Answer: Phenotypes: wild, vestigial, hairy, vestigial hairy; Numbers expected: wild (576), vestigial (192), hairy (192), vestigial hairy (64) Section: 3.3 34) Which phenotypic ratio is likely to occur in crosses of two completely dominant, independently segregating gene pairs when both parents are fully heterozygous? Answer: 9:3:3:1 Section: 3.3 35) Provide simple definitions that distinguish segregation and independent assortment. Answer: Segregation is the separation of alleles during meiosis; independent assortment states that a member of one gene pair has an equal and independent opportunity of segregating with either member of another gene pair. Section: 3.3 36) Under what conditions does one expect a 9:3:3:1 ratio? Answer: dihybrid cross (F 2 ) with independently assorting, completely dominant genes Section: 3.3 37) Under what conditions does one expect a 1:1:1:1 ratio? Answer: This occurs in a cross involving doubly heterozygous individuals crossed to fully recessive individuals. The genes involved assort independently. Section: 3.3 7

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    38) What conditions are likely to apply if the progeny from the cross AaBb × AaBb appear in the 9:3:3:1 ratio? Answer: complete dominance, independent assortment, no gene interaction Section: 3.3 39) How many kinds of gametes will be expected from an individual with the genotype PpCcTTRr ? Answer: 8 Section: 3.4 40) For the purposes of this question, assume that being Rh + is a consequence of D and that Rh - individuals are dd . The ability to taste phenylthiocarbamide (PTC) is determined by the gene symbolized T ( tt are nontasters). A female whose mother was Rh - has the MN blood group, is Rh + and a nontaster of PTC, and is married to a man who is MM, Rh - , and a nontaster. List the possible genotypes of the children. Assume that all the loci discussed in this problem are autosomal and independently assorting. Answer: MMDdtt, MMddtt, MNDdtt, MNddtt Section: 3.4 41) Two organisms, AABBCCDDEE and aabbccddee , are mated to produce an F 1 that is self-fertilized. If the capital letters represent dominant, independently assorting alleles: a) How many different genotypes will occur in the F 2 ? b) What proportion of the F 2 genotypes will be recessive for all five loci? c) Would you change your answers to (a) and/or (b) if the initial cross occurred between parents? d) Would you change your answers to (a) and/or (b) if the initial cross occurred between parents? Answer: (a) 3 5 = 243 (b) 1/243 (c) no (d) yes Section: 3.4 42) Assuming independent assortment, what proportion of the offspring of the cross will have the aabbccdd genotype? Answer: zero Section: 3.4 43) How many different kinds of gametes can be produced by an individual with the genotype AABbCCddEeFf? Answer: 2 3 = 8 Section: 3.4 44) What is the probability of flipping a penny and a nickel and obtaining one head and one tail? Answer: 1/2 (apply the "sum law") Section: 3.7 8

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    45) Among dogs, short hair is dominant to long hair and dark coat color is dominant to white (albino) coat color. Assume that these two coat traits are caused by independently segregating gene pairs. For each of the crosses given below, write the most probable genotype (or genotypes if more than one answer is possible) for the parents. It is important that you select a realistic symbol set and define each symbol below. Assume that for cross (d), you were interested in determining whether fur color follows a 3:1 ratio. Set up (but do not complete the calculations) a Chi-square test for these data [fur color in cross (d)]. Answer: Let A = dark, a = albino and L = short, l = long a) AALl × AAll or AALl × Aall b) aaLl × aaLl c) AaLL × aaLL or AaLl × aaLL or AaLL × aaLl d) AaLl × AaLl χ 2 = Σ = (242 - 243) 2 /243 + (82 - 81) 2 /81 Section: 3.8 46) In what ways is sample size related to statistical testing? Answer: By increasing sample size, one increases the reliability of the statistical test and decreases the likelihood of erroneous conclusions from chance fluctuations in the data. Section: 3.8 47) In a Chi-square analysis, what condition causes one to reject (fail to accept) the null hypothesis? Answer: usually when the probability value is less than 0.05 Section: 3.8 48) If one is testing a goodness of fit to a 9:3:3:1 ratio, how many degrees of freedom would be associated with the Chi-square analysis? Answer: number of classes minus 1 = 3 Section: 3.8 49) Assume that a Chi-square test was conducted to test the goodness of fit to a 9:3:3:1 ratio and a Chi- square value of 10.62 was obtained. Should the null hypothesis be accepted? Answer: no Section: 3.8 50) Assume that a Chi-square test was conducted to test the goodness of fit to a 3:1 ratio and that a Chi- square value of 2.62 was obtained. Should the null hypothesis be accepted? How many degrees of freedom would be associated with this test of significance? Answer: yes; 1 Section: 3.8 9

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    51) Assume that a Chi-square test provided a probability value of 0.02. Should the null hypothesis be accepted? Answer: no Section: 3.8 52) Assume that a cross is made between a heterozygous tall pea plant and a homozygous short pea plant. Fifty offspring are produced in the following frequency: 30 = tall 20 = short a) What frequency of tall and short plants is expected? b) To test the goodness of fit between the observed and expected values, provide the needed statement of the null hypothesis. c) Compute a Chi-square value associated with the appropriate test of significance. d) How many degrees of freedom are associated with this test of significance? Answer: (a) 1:1 (25 tall and 25 short) (b) The deviations from a 1:1 ratio (25 tall and 25 short) are due to chance. (c) χ 2 = 2 (d) 1 Section: 3.8 53) In a Chi-square test, as the val ue of the χ 2 increases, the likelihood of rejecting the null hypothesis ________. [one word] Answer: increases Section: 3.8 54) In studies of human genetics, usually a single individual brings the condition to the attention of a scientist or physician. When pedigrees are developed to illustrate transmission of the trait, what term does one use to refer to this individual? Answer: proband Section: 3.9 55) Mendel's Law of Segregation is supported by a 1:1 testcross ratio. Answer: TRUE Section: 3.2 56) To test Mendel's Law of Segregation, the experimenter needs a minimum of two contrasting forms of a gene. Answer: TRUE Section: 3.2 57) A 1:1 phenotypic ratio is expected from a monohybrid testcross with complete dominance. Answer: TRUE Section: 3.2 58) Assuming complete dominance, a 3:1 phenotypic ratio is expected from a monohybrid sib or self- cross. Answer: TRUE Section: 3.2 10

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    59) A 9:3:3:1 phenotypic ratio is expected from a dihybrid testcross. Answer: FALSE Section: 3.3 60) Mendel's postulate of independent assortment is supported by a 1:1:1:1 testcross ratio. Answer: TRUE Section: 3.3 61) Mendel's discoveries were well received and understood by his contemporaries. Answer: FALSE Section: 3.5 62) The nonfunctional form of a gene is called a wild-type allele. Answer: FALSE Section: 3.5 63) A gene can have a maximum of two alleles. Answer: FALSE Section: 3.5 11

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