1. Gregor Mendel's work was generally misunderstood and not widely accepted until it was rediscovered in 1900 because a. his work was never published. b. he was a monk. c. his approach was mathematical. d. other scientists could not repeat his results. 2. Mendel's classic work in genetics studied the inheritance of traits in a. Drosophila melanogaster b. tobacco plants c. the garden pea d. ordinary house mice 3. Garden peas are generally true-breeding plants because they a. are all phenotypically alike. b. have a relatively small number of genes. c. do not make pollen. d. reproduce by self-fertilization. 4. The physical appearance of an individual plant or animal is known as its a. first filial generation. b. phenotype. c. genotype. d. recessive trait. 5. A cross between two true-breeding individuals differing at only one genetic locus is known as a a. monohybrid cross. b. reciprocal mating. c. second filial generation. d. dihybrid cross. 6. In a monohybrid cross between two individuals with different phenotypic traits, the first filial generation will a. all resemble the recessive parental type. b. all resemble the dominant parental type. c. resemble the dominant parent half of the time. d. resemble the dominant parent one-quarter of the time. 7. When the first filial generations of a monohybrid cross are allowed to self-fertilize, the observed ratio of dominant to recessive phenotypes in the second filial generation should be a. 2:1. b. 3:4. c. 3:2. d. 3:1. --- 8. When the first filial generations of a monohybrid cross are allowed to self-fertilize, the observed genotypic ratio of the progeny should be a. 3:1. b. 9:3:3:1. c. 1:2:1. d. 3:2. 9. The observation that plants with dominant phenotypes produce both dominant and recessive offspring led to the development of a. the principle of independent assortment. b. Mendel's first law. c. the theory of blending inheritance. d. All of these choices are true. 10. According to Mendel's first law, the gametes produced by a heterozygous individual will be a. 25% dominant alleles, 75% recessive alleles. b. independently assorted. c. half dominant alleles, half recessive alleles. d. all dominant alleles. 11. If a heterozygous individual is testcrossed to a recessive parent, the progeny will a. all resemble the dominant parent. b. show equal numbers of dominant and recessive phenotypes. c. all resemble the recessive parent. d. resemble the dominant parent 75% of the time. 12. For any given trait R where allele R is dominant over allele r, the probability of getting a gamete with the r allele is a. 0.25. b. 0.50. c. 0.75. d. 1.00. 13. The sum rule can be used to determine the probability of two events occurring if those events are a. equally likely to occur. b. independently assorting. c. mutually exclusive. d. conditional. 14. An example of mutually exclusive events is a. flipping two coins 10 times. b. having a boy and a girl in the same family. c. flipping one coin 20 times. d. one person having both blonde hair and blue eyes. --- 15. The statistical principle that can be used when predicting the outcome of a cross between two heterozygous individuals is the a. principle of segregation. b. binomial coefficient. c. product rule. d. sum rule. 16. The probability of obtaining a homozygous recessive individual in a cross between two heterozygotes is a. 0.25. b. 0.50. c. 0.625. d. 0.75. 17. The probability of obtaining a phenotypically dominant individual from a cross between two heterozygotes is a. 0.25. b. 0.50. c. 0.625. d. 0.75. 18. The probability that in a human family with six members, four will be girls is a. 0.133. b. 0.234. c. 0.068. d. 0.465. 19. The chi-square test measures a. the binomial coefficient of a set of data. b. the degrees of freedom for any given experiment. c. the expected outcome of genetic crosses. d. how well the expected and observed data correlate. 20. How many degrees of freedom would be used to determine statistical significance in an experiment involving four different categories? a. 4 b. 3 c. 2 d. 5 21. If a chi-square value for a given set of data exceeded the theoretical value found in a chi-square table, it can be assumed that the a. original hypothesis was correct. b. observed data is consistent with that expected. c. observed and expected data differ significantly. d. sum of the expected and observed data is equal to 1. --- 22. If 600 offspring resulted from a dihybrid cross of two AaBb individuals, how many of the offspring would have the parental phenotype? a. 338 b. 121 c. 600 d. 452 23. Mendel's assumption that ultimately led to his second law was that a. alleles segregate from one another during gamete formation. b. genes responsible for flower color were independent from all others. c. the principle of segregation was true for all genetic traits. d. alleles at separate loci assort independently from each other. 24. Two purebred plants, each producing white flowers, were crossed. All of the progeny had red flowers. When the red flowering plants were allowed to self-fertilize, 450 red flowering and 350 white flowering plants grew. These results indicate that flower color in these plants is determined by a. a single gene. b. two independently assorting genes. c. two linked genes. d. an undetermined method. 25. Assuming that all of the genes in the following example assort independently, what proportion of offspring from a cross between two AaBbCcDdEeFf individuals would be AABbCcDdeeFF? a. 1/512 b. 1/1024 c. 1/64 d. 1/128 26. What proportion of offspring from a cross between two AaBbCcDdEeFf individuals would exhibit the dominant phenotype for all traits? a. 512/1028 b. 425/3176 c. 127/2134 d. 729/4096 27. In snoogers, curly hair (C) is dominant over straight, red eyes (R) are dominant over white, and blue lips (B) are dominant over pink. Assuming that these genes assort independently, in a cross between a homozygous dominant individual and a homozygous recessive, what proportion of the progeny would be heterozygous for all three traits? a. 0.25 b. 0.50 c. 0.75 d. 1.00 --- 28. If two snoogers with the genotype CcRrBb mated, what proportion of their offspring would be CCrrBb? a. 1/2 b. 1/8 c. 1/16 d. 1/32 29. Determination of the mode of inheritance in humans is more difficult than in Drosophila because a. the generation time for Drosophila is shorter than for humans. b. human families are small relative to the offspring produced by Drosophila. c. Drosophila chromosomes carry fewer traits. d. All of these choices are true. 30. Which of the following is a characteristic of a recessive human disease? a. If both parents are affected, some of the offspring will have the disease. b. If both parents are affected, all of the offspring will have the disease. c. The trait is seen in every generation. d. If one parent is affected, all of the offspring will have the disease. 31. Which of the following is a characteristic of a dominant human disease? a. Parents with the trait are generally unaffected. b. Parents without the disease can't have affected offspring. c. The trait often appears in offspring of a consanguineous marriage. d. One-quarter of a trait-bearing individual's siblings will also have the trait. 32. An example of a recessive genetic disease that affects humans is a. Huntington's disease. b. achondroplasia. c. cystic fibrosis. d. All of these choices are true. 33. conditional probability 34. chi-square 35. sum rule 36. binomial probability 37. product rule a. The statistical test for goodness of fit b. The probability of an event occurring out of a number of total events c. The probability that two mutually exclusive events occur d. The probability of an event occurring which is contingent upon a set of given circumstances e. Determination of the joint probability of two independent events occurring --- 38. Mendel's first law states that genes on different chromosomes assort independently during the formation of gametes. 39. The physical manifestation of genetic traits in an organism is the genotype. 40. A testcross is a mating of an individual of unknown genotype with a heterozygous parent. 41. When a heterozygous organism is self-fertilized, the progeny should resemble the parent 75% of the time. 42. If two normal people marry and have a child who develops cystic fibrosis, one parent must be a heterozygous carrier of the disease. 43. Mendel's laws of inheritance have been shown to be true for all genetic loci. 44. Mendel's theory that actual physical genetic units were transmitted from generation to generation was termed __________ __________. 45. Garden peas are generally true-breeding because they reproduce primarily by __________. 46. In a monohybrid cross, reciprocal matings result in __________ progeny types. 47. Mendel suggested that the genetic units of inheritance can exist in many alternative forms, which are now called __________. 48. A cross between a heterozygous individual and its recessive parent is known as a __________. 49. An allele that is expressed only when homozygous is termed the __________ allele. 50. A gene that has two different alleles is __________ for that locus. 51. For an individual heterozygous for a particular trait, half of the gametes will have the dominant allele and half the recessive allele. This is known as the: a. principle of segregation b. the principle of independent assortment c. the principle of linkage d. the principle of codominance 52. Individuals that are Rr are crossed. The probability of an offspring being RR is __________, and the probability of an offspring being Rr is __________; thus, the probability of an offspring being either RR or Rr is ___________. --- 53. An allele on the X chromosome is lethal. A female heterozygous for such an allele is crossed with a normal male. Which of the following would be true? a. They would only produce females. b. They would produce males heterozygous for the allele. c. Half the females and half of the males would be affected by the trait. d. They would produce half as many male as female offspring. 54. Hemophilia and color blindness are examples of a. lethal alleles b. sex-linked traits c. sex-influenced traits d. traits produced by dominant autosomal alleles 55. One way to determine the influence of genotype on a given genotype-phenotype relationship is to: a. put identical organisms into different environments and observe the phenotypic reaction. b. grow the offspring from phenotypically different individuals in the same environment. c. observe how many different genotypes there are for a particular phenotype. d. observe several different phenotypes found in one environment. 56. For the following statements, choose which of the following terms match the statement: a. leptotene b. zygotene c. pachytene d. diplotene e. diakinesis Statements: A. Homologous chromosomes pair up. B. Paired chromosomes begin to separate, beginning at the centromeres, leaving regions of contact called chiasmata. C. Paired chromosomes shorten and thicken; recombination occurs. 57. The following change occurs in a chromosome: A B C D E F A B E D C F This would be a: a. translocation b. pericentric inversion c. paracentric inversion d. duplication --- 58. A reciprocal translocation results in the following types of chromosomes, which pair up as shown in meiosis I: Which chromosomes would have to segregate to produce balanced chromosomes? __________________________ 59. An individual has an extra X chromosome, thus being XXY. a. In fruit flies, the individual would be a female. b. In humans, the person would be a male with Klinefelter's syndrome. c. In humans, the effect of the extra X chromosome is a male lacking certain secondary sexual characteristics such as a beard. d. all of the above e. b and c only 60. Using somatic cell hybridization, a number of cells having a particular human enzyme were generated. Five of these cell lines had the following human chromosomes: (A) 4,9,11; (B) 2,9,11,21; (C) 4,9,10,21; (D) 1,2,9,18; (E) 4,9,11. On which chromosome is the gene located? ______________ 61. Individuals that are AaBbCc are mated to themselves (the genes are on separate chromosomes). What will be the expected frequency of progeny that are: a) aa? b) B-? c) cc? d) What will be the expected frequency of progeny that are aaB-cc? 62. If an individual was A-B-C-, how could you determine if it was homozygous or heterozygous? In a particular individual the genes on one chromosome are A B C (dominant) and on the homologous chromosome a b c (recessive). How could you know that the genes are linked, and that the dominant alleles are on one chromosome and the recessive alleles are on its homologue? 63. Two heterozygous individuals, Aa, are crossed, producing 69 A- offspring and 31 aa offspring. Using your tables of Chi-square values, what is the probability of this ratio occuring by chance? 64. Briefly explain how chromosomes provide a basis for segregation and independent assortment. --- 65. A true-breeding pea producing yellow peas is crossed with a true-breeding pea producing green peas. The offspring are all yellow. Describe: a. The genotype of the parents, using Y and y as symbols. b. The genotype of the offspring. c. If the offspring from part b are mated to each other, what would you expect for results? Describe the offspring of this mating both in terms of genotype and phenotype. 66. Two parents that are heterozygous for the trait for albinism (Aa) produce children. The probability of an offspring being AA is __________; the probability of an offspring being Aa is __________; the probability of an offspring being either AA or Aa is __________. 67. The combination of the seed shape (R,r: alleles for round or wrinkled seeds) and color (Y,y: alleles for yellow or green seeds) are found in two pea plants. The two pea plants, that are RrYy, are crossed. This cross will illustrate: a. the law of segregation. b. the law of recombination. c. the law of independent assortment. d. the law of co-dominance. 68. Two normal individuals produce a child with sickle-cell anemia. Since the parents were normal, sickle-cell anemia is probably the result of: a. a dominant allele b. a recessive allele c. simultaneous mutations in both parents d. one parent playing too much nintendo 69. An individual has a parent with Huntington's disease, a disease caused by a dominant allele. The probability that he or she will have the disease (it shows up later in life) is thus: a. 1/4 b. 1/2 c. 3/4 d. 0 --- 70. Two peas producing white flowers have offspring that all have purple flowers. The trait is caused by two genes, C and P; for purple flowers to be produced, the plant needs both a C and a P allele. The genotypes of the parents are CCpp and ccPP. a. What is the genotype of the F1 generation? b. If the F1 is crossed with itself to produce an F2 generation, what will be the frequency of purple-flowered offspring? (Note: using a forked-line approach will give you the answer more quickly). c. The type of situation discribe is known as: a. complementary gene action b. additive gene action c. incomplete dominance d. co-dominance. d. Why are the two gene required to produce purple color? 71. A plant producing red flowers is crossed with one producing white flowers. the offspring have pink flowers. This is an example of a. co-dominance b. complemintary gene action c. pleiotropy d. incomplete dominance. How would you explain the above results? 72. Two populations can have the same mean, but different variance. Use the graph above to show a population with the same mean, but less variance as the one shown. 73. A trisomic individual can result from: a. translocation of a small chromosome onto a larger chromosome. b. nondisjunction during meiosis, but only at meiosis I. c. nondisjunction during either meiosis I or II (i.e., metaphase I or II). d. both a and b. e. both a and c. 74. What is heritability? If you ahd a population of pigs and could breed them experimentally, how would you determine the heritability of body weight in those pigs? --- 75. A mutant E. coli strain is unable to grow in the absence of thymine. These mutants are called Thy-, and this characteristic would be its: a. phenotype b. geneotype c. haplotype d. allelotype 76. When a mutant E. coli is unable to grow in the absence of thymine, it is called Thy-. If a Thy- mutant contains a cloned copy of a functional gene for thymine synthesis, it is then able to grow in the absence of thymine. This means that the mutation causing this trait was: a. dominant b. recessive c. co-dominant d. pleiotropic 77. You have a pea plant making yellow peas; yellow (Y) is dominant to green (y). You wish to determine if it is homozygous (YY) or heterozygous (Yy). You would: a. cross your plant with a known YY plant; if all the offspring produced yellow peas, the unknown plant was YY; if 1/4 are green, it was Yy. b. cross your plant with one producing green peas (yy). If all the offspring produce green peas, your plant is Yy. c. cross your plant with one producing green peas (yy). If half of the offspring produce green peas, your plant is Yy. d. cross your plant with one producing green peas (yy). If all the offspring produce yellow peas, your plant is Yy. 78. We have studied a number of traits by Mendelian genetics and by molecular genetics. For one of the descriptions listed below, give a molecular basis for the first one, and then one of the others. a. One allele is dominant, the other is recessive. b. Two alleles are co-dominant. c. Two mutants, both unable to produce a pigment, are crossed; the offspring are all colored. d. A plant with red flowers is crossed with one with white flowers; the offspring have pink flowers. 79. A yellow-bellied sapsucker mated with a blue-bellied sapsucker and had green-bellied offspring. This indicates that the alleles responsible for belly color in sapsuckers a. are codominant. b. show complete dominance of one allele. c. show incomplete dominance. d. are recessive. --- 80. Upon closer examination, it is discovered that green-bellied sapsuckers have both blue and yellow feathers. This indicates that the belly color alleles a. are incompletely dominant at the genotypic level. b. are codominant at the genotypic level. c. are codominant at the gross phenotypic level. d. show complete dominance of the blue allele. 81. Lethal alleles cause __________ mortality in affected individuals. a. 100% b. 75% c. 50% d. 25% 82. Lethal alleles are generally a. dominant. b. incompletely dominant. c. recessive. d. heterozygous. 83. Genes that affect more than one trait in an individual are a. codominant. b. deleterious. c. pleiotropic. d. heterozygous. 84. In humans, type AB blood is an example of a. codominance. b. pleiotropy. c. incomplete dominance. d. incomplete penetrance. 85. A genetic disease in humans that is related to the pleiotropic effect of certain genes is a. Huntington's disease. b. alcaptonuria. c. Parkinson's disease. d. phenylketonuria. 86. Phenylketonuric individuals often have small heads and light-colored hair in addition to being unable to metabolize phenylalanine. This indicates that phenylketonuria is a. an incurable disease. b. caused by a dominant allele. c. pleiotropic. d. caused by incomplete penetrance of an allele. --- 87. Scientists studying a recessive disease have found that some individuals who inherit two recessive alleles do not show any disease symptoms. This indicates that the gene responsible for the disease is a. incompletely penetrant. b. conditionally lethal. c. pleiotropic. d. a modifier. 88. Four individuals in a family of five that has a history of a rare genetic disease are homozygous recessive for the gene responsible for the disease. Only three of the members had disease symptoms. This indicates that the gene is a. not actually responsible for the disease. b. variably expressive in this family. c. incompletely penetrant. d. pleiotropic. 89. A genetic disease was found to be expressed in only 5 homozygous recessive individuals out of 8 tested. The level of penetrance for this gene is a. 0.125. b. 0.50. c. 0.625. d. 0.75. 90. Phocomelia is a rare genetic disorder that results in infants born with severely shortened arms and legs. Thalidomide is a(n) __________ of phocomelia. a. cause b. type c. phenocopy d. allele 91. An example of a gene with multiple alleles is a. ABO blood group in humans. b. HLA antigen system in humans. c. wing color in the peppered moth. d. All of these choices are true. 92. The schleep is a diploid organism in which coat color is determined by a gene with seven different alleles. How many different genotypes for coat color can a schleep have? a. 7 b. 14 c. 21 d. 28 93. If a diploid organism has seven alleles at one particular locus, how many of the genotypes for that locus would be heterozygous? a. 7 b. 14 c. 21 d. 28 --- 94. The HLA system in humans has such a large number of heterozygous genotypes because a. the alleles are incompletely dominant. b. the loci have multiple alleles. c. one allele is completely dominant. d. the alleles are not codominant. 95. Color blindness in humans is an a. autosomal recessive disease. b. X-linked dominant trait. c. autosomal dominant trait. d. X-linked recessive trait. 96. The second filial generation resulting from a monohybrid cross for an autosomal gene is different from the second filial generation from a similar cross of an X-linked gene in that, for the X-linked cross, a. all progeny with a recessive phenotype would be male. b. all of the progeny would be female. c. only heterozygous genotypes would be found. d. recessive genotypes would be lethal. 97. Traits that are expressed only in males and are always passed from father to son are __________ traits. a. X-linked b. autosomal recessive c. Y-linked d. autosomal dominant 98. Genes that are determined autosomally and expressed only in a male are a. autosomal recessive. b. sex-limited. c. Y-linked. d. sex-influenced. 99. Traits that occur almost entirely in males and skip generations in families are a. X-linked recessive. b. Y-linked. c. autosomal recessive. d. X-linked dominant. 100. Hair color in humans has been found to be related to a number of different genes. This is an example of a. complete dominance. b. epistasis. c. phenocopy. d. multiple alleles. --- 101. Epistasis is different from multiple alleles at a loci, in that epistasis a. is the phenotypic result of the summing of many different genes. b. is characterized by heterozygosity at two or more loci. c. is the phenotypic result of having different alleles at one locus. d. results when two or more genes interact to determine a phenotype. 102. One way to determine the influence of environment on a given genotype-phenotype relationship would be to a. put identical organisms into different environments and observe the phenotypic reaction. b. observe several different phenotypes found in one environment. c. observe how many different genotypes there are for a particular phenotype. d. remove a variety of organisms from their normal habitats and keep them together in one environment. 103. Which of the following is a qualitative trait? a. neck length in giraffes b. wool production by sheep c. tail length in rats d. All of these choices are true. 104. Which of the following statements regarding qualitative traits is true? a. They are not subject to environmental influences. b. They tend to be polygenic. c. They show a precise genotype-phenotype relationship. d. All of these choices are true. 105. A number of plants are removed from three extremely different environments, and are all planted in a greenhouse in which temperature, light, and moisture are kept constant. After several generations, it is observed that the plants still look like the original transplanted generation. This suggests that a. environmental factors have influenced the phenotypes of the progeny plants. b. both environmental and genetic factors are influential in determining the appearance of the progeny. c. the plants are genetically different. d. the environmental influence can't be determined. 106. Identical twins are genetically identical. If two identical twins were raised in separate environments, which of the following traits might show phenotypic variation? a. eye color b. height c. intelligence d. fingerprints --- 107. If both parents in a family are heterozygous carriers of a recessive disease and have three children, what is the probability that none of their children will be affected by the disease? a. 0.50 b. 0.42 c. 0.28 d. 0.16 108. Which of the following HLA genotypes would allow a man to be excluded as the father of a child with an HLA genotype of A2, A11; B15, B37? a. A1, A11; B8, B12 b. A1, A2; B7, B15 c. A3, A11; B27, B37 d. A11, A25; B37, Bw41 109. The principle of segregation can be applied to recessive lethal genetic diseases. 110. Multiple alleles at any given locus are fairly common in many populations. 111. ABO blood groups in humans are an example of incomplete dominance. 112. Incomplete penetrance of a gene can be influenced by environmental situations. 113. Epistasis results in a phenotype that is actually the sum effect of a number of different genes acting independently. 114. Interaction of alleles found at two or more genes always results in the expected 9:3:3:1 genotypic ratio in the second filial generation. 115. The interaction of genes to jointly produce one specific gene product is known as complementary gene action. 116. Duplicate gene action is a form of epistasis. 117. Environmental factors do not appreciably influence the phenotype for any given genotype. 118. Genes affecting qualitative traits follow Mendelian patterns of inheritance. 119. Genetic variation is approximately __________ in inbred populations, clones, and identical twins. 120. A large proportion of rare genetic diseases are inherited as __________ __________ genes. 121. The empirical risk of recurrence of a genetic disease __________ as the number of affected sibs increases. --- 122. Genetic determination of quantitative traits __________ among different populations. 123. HLA paternity testings determine if a man can be __________ as the father of a child. 124. What estimation of phenotypic traits do plant and animal breeders use to improve their yields? 125. How does codominance of alleles differ from incomplete dominance? 126. What can be said of a trait that results in mortality in the homozygous state? 127. An autosomal recessive disorder causes the noses of affected individuals to grow when they tell an untruth. In some individuals noses grow to 10 inches; in others only 5 inches. What can be said about the gene responsible for this disease? 128. What type of distribution pattern is normally seen for a quantitative trait? 129. During crosses involving Drosophila, Thomas Hunt Morgan observed a white-eyed mutant in a culture of wild-type flies. Crosses between the mutant and wild-type flies showed that the mutation was recessive to the wild-type allele. All of the mutant phenotypes were male. Reciprocal crosses gave different results. This data suggested that a. eye color was an autosomal recessive trait. b. the gene for eye color was located on the X chromosome. c. homozygous recessive females died in utero. d. nondisjunction of chromosomes during meiosis had occurred. 130. The final proof that genes definitely are contained on chromosomes came with Bridge's discovery that a. white-eyed female Drosophila were the result of meiotic nondisjunction. b. the red-eyed allele was dominant over the white-eyed allele. c. eye color in Drosophila was X-linked. d. female Drosophila had two X chromosomes. 131. The number of chromosomes found in a zygote is referred to as an organism's __________ chromosomal number. a. meiotic b. haploid c. constitutive d. diploid 132. The type of cell division that results in the production of male and female gametes is a. meiosis. b. gametogenesis. c. sporogenesis. d. All of these choices are true. --- 133. During a karyotyping procedure, a chromosome is observed with a centromere very close to one end. This chromosome is a. metacentric. b. acrocentric. c. telocentric. d. heterocentric. 134. The telomeric region of a chromosome refers to a. a region at each end of the chromosome that is chemically different from the rest. b. a constricted area located near the center of the chromosome. c. the region surrounding the centromere. d. the region of the chromosome that is genetically active. 135. A scientist mixes up a batch of cultured human cells with some cultured mouse cells. She performs a karyotype on both sets of cells. How can she determine which culture contained the human cells? a. Human chromosomes are all metacentric. b. Mouse chromosomes are all telocentric. c. Human chromosomes are both telocentric and metacentric. d. Mouse chromosomes are both acrocentric and metacentric. 136. Polytene chromosomes are giant chromosomes found in a. humans. b. mice. c. fruit flies. d. plants. 137. When does mitosis occur during the cell cycle? a. after G1 but before S b. before G2 c. immediately following DNA replication d. following G2 138. Which of the following is the correct order of events for mitosis during the cell cycle? a. interphase - metaphase - anaphase - telophase - prophase b. interphase - prophase - metaphase - anaphase - telophase c. interphase - anaphase - metaphase - telophase - prophase d. interphase - prophase - anaphase - metaphase - telophase 139. During what phase of mitosis are karyotypes usually performed? a. prophase b. metaphase c. telophase d. interphase 140. The mitotic phase that is characterized by disappearance of the nucleolus and development of the spindle apparatus is a. prophase. b. metaphase. c. anaphase. d. telophase. --- 141. In humans, the cell divisional process of meiosis is important for maintaining genetic integrity and also for creating genetic variation because a. diploid chromosome number must be maintained. b. different types of chromosomes come together to form a zygote. c. crossing over occurs during meiosis. d. All of the above are true. 142. The end result of meiosis I is the a. separation of homologous chromosomes into 2 daughter cells. b. formation of 2 daughter cells, each containing the diploid chromosome number. c. separation of the duplicated chromosomes into 4 daughter cells. d. formation of 4 daughter cells, each containing the haploid chromosome number. 143. Recombinational exchange of genetic material between homologous chromosomes can occur during a. the diplotene stage of prophase I. b. prophase II. c. the pachytene stage of prophase I. d. metaphase I. 144. The synapsis process that occurs during the zygotene stage in prophase I of meiosis is the process in which a. homologous chromosomes pair side-by-side. b. chiasmata are formed. c. recombination between homologous chromosomes occurs. d. All of these choices are true. 145. The production of male gametes in mammals is called a. sporogenesis. b. oogenesis. c. microsporogenesis. d. None of these choices are true. 146. A duplication of some of the genes on a chromosome can result from a. mispairing during prophase of meiosis I. b. a paracentric inversion. c. breakage and reunion of nonhomologous chromosomes. d. All of these choices are true. 147. A woman appears to be perfectly healthy, but she only has 45 chromosomes. This could be due to a(n) a. inversion. b. duplication. c. translocation. d. deletion. --- 148. Which type of chromosomal change can result in the formation of new genetic types in a population? a. deletion b. translocation c. inversion d. duplication 149. Which of the following is characteristic of a deletion mutation? a. Reversion to wild-type frequently occurs. b. It does not usually result in a lethal condition. c. Recessive alleles suddenly become expressed. d. Chromosomes pair normally during meiosis. 150. During early anaphase I of meiosis, how would the chromosomes of a reciprocal translocation heterozygote undergoing alternate segregation appear when viewed microscopically? a. Individual chromosomes would not be seen. b. They would appear in rings of two or more bivalents. c. They would appear in a figure eight. d. They would appear unbalanced. 151. During the preparation of a karyotype on a culture of human cells, it appears that the number of chromosomes is only 45. Closer examination shows that there are actually 46 chromosomes, but one is a very small acentric chromosome and one is a large metacentric. What is a possible explanation for this observation? a. Two chromosomes underwent a chromosomal fusion. b. The individual who donated the cells was an autopolyploid. c. An interstitial translocation occurred between two homologous chromosomes. d. This is an expected result of meiosis. 152. A polyploid organism that receives all of its chromosomal sets from parents of the same species is a. allopolyploid. b. autopolyploid. c. allotetraploid. d. aneuploid. 153. In an allopolyploid organism, chromosomal sets are homologous. This means that the chromosomal sets making up an allopolyploid a. are exactly the same. b. vary slightly. c. are identical to the dominant parental type. d. are obtained from parents of the same species. 154. A classic example of autosomal polyploidy in humans is a. Down syndrome. b. Turner's syndrome. c. Klinefelter's syndrome. d. All of these choices are true. --- 155. The number of Barr bodies that would be detected in an individual with Klinefelter's syndrome is a. 0. b. 1. c. 2. d. 3. 156. In humans, females are the __________ sex. a. hemizygous b. hermaphroditic c. heterozygous d. heterogametic 157. Nondisjunction resulting in aneuploidy can occur a. during mitosis. b. during meiosis. c. during mitosis or meiosis. d. only in the heterogametic sex. 158. Sex determination in yoyos was found to resemble that of Drosophila. A karyotype done on one yoyo showed two X chromosomes and 5 sets of autosomes. This individual would be a(n) a. male. b. female. c. metafemale. d. intersex. 159. Sexual reproduction occurs when an individual organism produces new individuals identical to itself. 160. In humans, the haploid chromosomal number is 46. 161. The process of cell division in a zygote is mitosis. 162. Eukaryotic organisms all share the same number of chromosomes. 163. Heterochromatic, or light-staining, regions of chromosomes remain generally constant within members of the same species. 164. Anaphase is usually the shortest period of mitosis. 165. Chromosome number is reduced to the haploid number through meiosis. 166. When chromosomal damage such as a breakage occurs in an organism, the end result is always lowered fertility or mortality. 167. Expression of recessive alleles in deletion heterozygotes is called pseudodominance. 168. A translocation occurs when a segment from one chromosome is moved to a second homologous chromosome, with or without reciprocal exchange. --- 169. Although Mendel didn't realize it at the time, his observed data regarding segregation of alleles into two different cells was physically the result of __________. 170. Reciprocal translocation heterozygotes show a ringlike shape at the end of metaphase I in meiosis when they are undergoing __________ __________. 171. Translocation heterokaryotypes show normal meiotic products when __________ segregation of chromosomes occurs. 172. Down syndrome is the result of production of a(n) __________ set of chromosomes in a reciprocal translocation heterozygote. 173. Diploid organisms that have three or more sets of chromosomes are called __________. 174. Genetically, what is the major difference between heterochromatic and euchromatic regions of a chromosome? 175. What are sister chromatids? 176. Why are karyotypes done on cells that have been blocked in metaphase? 177. What are two major differences between mitosis and meiosis? 178. What are four types of changes in structure that chromosomes can undergo? 179. Two wild-type genes, s+ and m+, are found on one chromosome. The other homologous chromosome carries the recessive mutant alleles, s and m. This gene arrangement is called a. recombinant. b. repulsion. c. coupling. d. coincidental. 180. Consider the following arrangement of alleles on two homologous chromosomes: a+ b+ a b Crossing over between these two genes during meiosis would result in which of the following recombinants? a. a+b and ab+ b. a+b+ and ab c. a+a and b+b d. ab and ab 181. Recombination is most likely to occur between a. genes located close to one another on one chromosome. b. genes located far apart from one another on the same chromosome. c. genes on two different nonhomologous chromosomes. d. genes that have a low rate of recombination. --- 182. Which of the following would be an example of alleles in the repulsion phase? a. k+j+/kj b. k+j/kj+ c. k+j/k+j d. k+j+/k+j+ 183. Which of the following is an example of a coupling double heterozygous genotype? a. a+h+/ah b. a+h/ah+ c. a+h+/a+h d. a+h/a+h 184. In a testcross in which the progeny were observed for the presence of two linked genes, k and m, 200 recombinant phenotypes out of 2,401 progeny resulted. How far apart are k and m? a. 2 map units b. 2.4 map units c. 8 map units d. 12 map units 185. Examination of testcross data in Drosophila showed that two linked genes, p and q, had a recombination rate of 0.05. A third gene, d, had recombination rates of 0.241 and 0.191 with p and q, respectively. What is the order of these three genes on the chromosome? a. p-d-q b. p-q-d c. q-d-p d. d-p-q 186. For a testcross between any two organisms, the percentage of recombinants observed in the progeny cannot exceed a. 10%. b. 25%. c. 50%. d. 100%. 187. Two genes will not exhibit linkage in genetic crosses if a. they are far apart on the same chromosome. b. the rate of recombination between them is 0.5. c. they are on different chromosomes. d. All of these choices are true. 188. In a cross between two individuals whose genotypes are AaBb, where A is dominant to a, and B is dominant to b, the progeny are observed to show the following phenotypes: 1,800 AB, 600 Ab, 600 aB, and 200 ab. This data indicates that genes A and B a. are far apart on the same chromosome. b. are close together on the same chromosome. c. show linkage. d. independently assort. --- 189. When two genes are closely linked, the measure of interference of one crossover event on another a. approaches zero. b. is approximately 0.5. c. is close to unity. d. cannot be determined. 190. Double crossovers occur infrequently between closely linked genes because a. only genes distant from one another show interference. b. chromosomes aren't flexible enough to allow it. c. the position of the centromere can block recombination. d. different recombinational events occur independently of one another. 191. The rate of recombination between two genes that are far apart on a chromosome should be fairly high, but observed recombinational frequencies are often less than expected because a. an odd number of recombinational events will result in a nonrecombinant phenotype. b. an even number of recombinational events will result in a recombinant phenotype. c. an odd number of recombinational events will result in a recombinant phenotype. d. an even number of recombinational events will result in a nonrecombinant phenotype. 192. In organisms, such as humans, that have a chromosomal mechanism for sex determination, the rate of recombination between autosomal genes a. is higher in females than in males. b. is higher in the homogametic sex. c. is lower in the homogametic sex. d. is approximately the same. 193. Using somatic cell hybridizations, a particular human gene can be mapped to a chromosome if a. the protein product of the gene can be differentiated from mouse gene product. b. mouse and human cells can be fused. c. a stable diploid with both mouse and human chromosomes can be maintained. d. All of these choices are true. 194. Tetrad analysis in what organism has led to a better understanding of the process of recombination? a. Escherichia coli b. Neurospora crassa c. Drosophila melanogaster d. Homo sapiens --- 195. The distance in map units between two genes on a chromosome is determined to be 18.6 microns. This indicates that a. the two genes must be linked. b. there is very little probability of a double crossover event occurring. c. there are no other loci between the two genes. d. approximately 19% of the gametes formed show recombination between the two genes. 196. Three genes, a, b, and c, are on the same chromosome. The map distance between a and b is 5.4 map units. Genes b and c are 11.4 microns apart. The probability of a double crossover occurring in the region of these three genes is a. 0.006. b. 0.012. c. 0.164. d. 0.200. 197. Crossing over was first shown to occur after chromosome replication, during meiosis I, by a. attached X chromosome analysis in Drosophila. b. tetrad analysis in Neurospora. c. deletion mapping in humans. d. three-point crosses in yeast. 198. Two genes, m and s, are 8.1 map units apart on a chromosome. Two other genes, Ph and d, are 11.7 microns apart on the same chromosome. Direct examination of the DNA shows that Ph and d are actually closer to one another than m and s are to one another. This indicates that a. recombination between m and s occurs at a higher than expected frequency. b. recombination can't occur between Ph and m. c. recombination between Ph and d occurs at a higher than expected frequency. d. Ph and m will not show linkage in genetic crosses. 199. Human chromosome mapping by somatic cell hybridization exploits the fact that in fusions between mouse and human cells a. genes found on the mouse chromosomes are not expressed. b. human genes are not expressed. c. the nuclei of the fused cells remain separate. d. human chromosomes are lost from the hybrid cells. 200. Two genes are determined to be 57.3 map units apart on a chromosome. The percentage of offspring that will have a recombinant phenotype is a. 25%. b. 28.7%. c. 50%. d. 57.3%. --- 201. Map distance generally corresponds closely to the physical distance between two genes except a. in the centromeric region. b. between homeotic genes. c. in the region between closely linked genes. d. on the X chromosome. 202. Which of the following is true regarding recombination? a. Recombination occurs in the centromeric region of most chromosomes. b. Recombination occurs frequently between closely linked genes. c. Recombination is often localized to specific chromosomal regions. d. Recombination occurs before replication of chromosomal DNA is completed. 203. An sP/Sp female that underwent one crossover event could produce which of the following gametes? a. sP or Sp b. SP or sp c. Ss or Pp d. SS or PP 204. Genes s and t are 18.3 map units apart on a chromosome. Genes u and v are 10.5 microns apart on a second chromosome. The rate of recombination between s and u is a. 0.105. b. 0.183. c. 0.288. d. 0.500. 205. The observed frequency of double recombination between two genes would be lower than the expected frequency if a. the genes were far apart on one chromosome. b. the genes were closely linked. c. one crossover event did not interfere with the second. d. the first crossover event involved the centromere. 206. Which of the following is an example of a double heterozygote in the repulsion phase? a. pu/PU b. Pu/pU c. Pu/Pu d. PU/pu 207. A translocation can be useful in mapping a particular gene to a region of a chromosome if a. the gene is homeotic. b. the gene is X-linked. c. the translocation does not result in a lethal condition. d. the translocation can be detected in a mouse-human hybrid. --- 208. Interference between recombinational events results in a. a decrease in the frequency of double crossovers occurring between linked genes. b. a decrease in the number of crossovers occurring between genes on different chromosomes. c. an increase in the frequency of crossovers between linked genes. d. an increase in the frequency of double crossovers occurring between genes on different chromosomes. 209. The gene for which of the following genetic disorders was mapped using standard genetic analysis, and not RFLPs? a. Huntington's disease b. Cystic fibrosis c. Duchenne muscular dystrophy d. Manic depression in Old Order Amish 210. In order for a disease gene to be identified by RFLP analysis, it must be a. closely linked to a standard genetic marker. b. part of a multigene family. c. an autosomal recessive gene. d. closely linked to a RFLP. 211. Linkage refers to alleles found on two different but homologous chromosomes. 212. Two genes are located far apart from one another on a chromosome and do not show linkage in genetic crosses. Therefore, these genes cannot be considered syntenic. 213. Genes far apart on a chromosome might not show evidence of linkage during genetic crosses. 214. When genes are linked, but distant, on a chromosome, an even number of recombinational events between them will result in progeny showing parental chromosome types. 215. In three-point crosses, progeny that represent the occurrence of double crossover events make up the largest class of recombinants. 216. It is possible for more than one recombinational event to occur on a chromosome. 217. Interference between two crossover events cannot occur between genes that are far apart on a chromosome. 218. The rate of recombination between autosomal genes is often higher in women than in men. 219. The human genome is roughly ten times larger than the Drosophila genome. --- 220. Recent experimental data indicates that recombination occurs before chromosomes are replicated. 221. The __________ is the structure that allows scientists to view the event of recombination microscopically. 222. An individual with two different coupling chromosomes is a __________ __________ __________. 223. If two genes were located one map unit apart on a chromosome, the rate of recombination between these genes would be approximately __________. 224. Because of the effects of __________, closely linked genes sometimes show a lower than expected frequency of recombination. 225. Nonrecombinant phenotypes appear in gametes when there are an __________ number of recombinational events between two genes. 226. How do coupling gametes differ from repulsion gametes? 227. What features of the human X chromosome make it relatively easy to map? 228. How can a deletion heterozygote be differentiated from a homozygous individual? 229. What is a possible origin of linked genes that have similar structures and functions? 230. What is the advantage of using a haploid organism such as Neurospora in studies on recombination?