Have an account?
Skip to Content
Build your own quiz
Suggestions for you
132 questions
Show Answers
See Preview
- 1. Open EndedHow did Mendel use self-pollination and cross-pollination techniques in his experiments with flower color to observe the basic patterns of inheritance?
- 2. Open EndedWhat can be concluded from Gregor Mendel's experiments with pea plants?
- 3. Open EndedKomodo dragons are sexually reproducing lizards with separate male and female individuals. Sex is determined by the ZW system. Males have two copies of the same type of sex chromosome, and females have sex chromosomes of different sizes that contain different genes. Select the term that describes the organization of the sexual organs in the Komodo dragon.
- 4. Open EndedMiniature wings, Xm, in Drosophila melanogaster result from an X-linked allele that is recessive to the allele for long wings, X+. Match the genotypes for each parent in the crosses below.
- 5. Open EndedPhenylketonuria (PKU) is a disease that results from a recessive gene. Two normal parents produce a child with PKU. What is the probability that a sperm from the father will contain the PKU allele? What is the probability that an egg from the mother will contain the PKU allele? What is the probability that their next child will have PKU? What is the probability that their next child will be heterozygous for the PKU gene?
- 6. Open EndedCoat color in cats is determined by genes at several different loci. At one locus on the X chromosome, one allele (X+) encodes black fur and another allele (XO) encodes orange fur. Females can be black (X+X+), orange (XOXO) or a mixture of orange and black called tortoiseshell (X+XO). Males are either black (X+Y) or orange (XOY). Bill has a female tortoiseshell cat named Patches. One night, Patches escapes from Bill's house, spends the night out, and mates with a stray male. Patches later gives birth to the following kittens: one orange male, one black male, two tortoiseshell females, and one orange female. Give the genotypes of Patches, her kittens, and the stray male with which Patches mated.
- 7. Open EndedIdentical, or monozygotic, twins develop from a single egg fertilized by a single sperm. Monozygotic twins are genetically identical because they originate from a single zygote that split into two. Caroline Loat and her colleagues examined nine measures of social, behavioral, and cognitive ability in 1000 pairs of both male and female identical twins. Their study found that pairs of male twins tended to be more alike in their prosocial behavior, peer problems, and verbal ability scores than pairs of female twins. What explains this observation?
- 8. Open EndedIn humans, oculocutaneous (OCA) albinism is a collection of autosomal recessive disorders characterized by an absence of the pigment melanin in skin, hair, and eyes. That is, normal pigmentation (A) is dominant over albino characteristics (a). For this question, assume it is a single gene with two alleles. If both parents have normal pigmentation, what are all of the possible genotypes that may be observed in their offspring?
- 9. Open EndedA man, Joe, has classic hemophilia, an X-linked recessive disease. Classify each person depending on whether or not Joe could have inherited the hemophilia gene from him or her. Options: maternal grandmother, paternal grandmother, maternal grandfather, paternal grandfather
- 10. Open EndedTwo heterozygous pea plants for two different genes are crossed. One gene codes for seed color, where yellow (Y) is dominant over green (y). The other codes for seed texture, where round (R) is dominant over wrinkled (r). 1) 192 peas are produced. Determine the expected number of yellow and wrinkled offspring. 2) Now suppose one of the pea plants is homozygous recessive for both genes, resulting in the cross YyRr*yyrr. Calculate the percentage of green and wrinkled offspring. 3) Suppose one of the pea plants is homozygous recessive for seed color, resulting in the cross YyRr*yyRr. What is the ratio of phenotypes of the offspring?
- 11. Open EndedOf the following ideas postulated by Gregor Mendel, which one requires at least two genes to be demonstrated?
- 12. Open EndedSuppose a novel disease has been studied in several families and is known to be caused by a mutation in one gene. The "table" below shows families where the disease is present. The four rightmost columns are the offspring of the father and mother listed in that row. a) Select the most likely mode of inheritance of the disease. b) Select the description that best matches the male parent in family 3. c) Select the description that best matches the female parent in family 6.
- 13. Open EndedIn some reptilian species, temperature determines the sex of an embryo. The graph below shows the effect of temperature on the percentage of male reptilian embryos, where Tp is the pivotal temperature. What statement best describes the influence of temperature on the percentage of male or female offspring as shown by the graph?
- 14. Open EndedAt the end of your biology class, your professor asks you to develop a project to determine the genotype of a plant with red flowers. Red petal color (R) is dominant to pink flower color (r). To accomplish this task, you cross the plant with the unknown genotype with heterozygous red-flower (Rr) plants. Which of the following are valid predictions of the ratio of flower colors in the offspring?
- 15. Fill in the BlankAnhidrotic ectodermal dysplasia is an X-linked recessive disorder in humans characterized by small teeth, no sweat glands, and sparse body hair. The trait is usually seen in men, but women who are heterozygous carriers of the trait often have irregular patches of skin with few or no sweat glands (see the illustration). a) Irregular patches of skin lacking sweat glands in heterozygous female carriers of anhidrotic ectodermal dysplasia are caused by _______________. b) Why does the distribution of the patches of skin lacking sweat glands differ among the females depicted in the illustration, even between the identical twins?
- 16. Open EndedIn watermelons, bitter fruit (B) is dominant over sweet fruit (b), and yellow spots (S) are dominant over no spots (s). The genes for these two characteristics assort independently. A homozygous plant that has bitter fruit and yellow spots is crossed with a homozygous plant that has sweet fruit and no spots. The F1 are intercrossed to produce the F2. a) What will be the phenotypic ratio in the F2? b) If an F1 plant is backcrossed with the bitter, yellow-spotted parent, what phenotypes and proportions are expected in the offspring? c) If an F1 plant is backcrossed with the sweet, nonspotted parent, what phenotypes and proportions are expected in the offspring?
- 17. Open EndedMatch each phenotype description to its corresponding sex-chromosome genotype in humans: XX with SRY on X XO XXXX XXY XYY
- 18. Open EndedIn Caenorhabditis elegans, the level of expression of genes on both X chromosomes of females is reduced by half. What phenomenon is this an example of?
- 19. Open EndedIn pea plants, the allele for red color, F, is completely dominant to the allele for white flower color, f. Complete the Punnett square showing the genotypes possible among the offspring when two heterozygous individuals are crossed. Use the info from the Punnett square to answer the second question. In this cross between two heterozygous pea plants, what are the chances that an offspring with red flowers will be produced?
- 20. Open EndedHow is a true breeding round-seeded pea plant different from a hybrid round-seeded pea plant?
- 21. Open EndedHow is a true breeding yellow-seeded pea plant different from a hybrid yellow-seeded pea plant?
- 22. Open EndedIn pea plants, plant height is controlled by a single autosomal dominant gene. Tall plants (H) are dominant to short plants (h). In a cross of two tall heterozygous plants (Hh*Hh), which phenotype ratio is expected from the resulting offspring?
- 23. Open EndedIn fruit flies, gray bodies (G) are dominant over black bodies (g), and red eyes (R) are dominant over orange eyes (r). Each individual possesses two alleles for each trait. If a fly that is homozygous dominant for both traits is crossed with a fly that is homozygous recessive for both traits, what is the predicted genotype of the offspring?
- 24. Open EndedIn butterflies, sex is determined by the ZW sex-determination system. Female butterflies are heterogametic and have both a Z sex chromosome and a W sex chromosome for sex determination. In contrast, male butterflies are homogametic and have two Z sex chromosomes. What are all of the relatives that a female butterfly could have inherited her Z sex chromosome from? Father, paternal grandmother, maternal grandfather, and/or mother
- 25. Open EndedAlleles A and a are located on a pair of metacentric chromosomes. Alleles B and B are located on a pair of acrocentric chromosomes. A cross is made between individuals having the following genotypes: AaBb x aabb. A) Label the gametes of the aabb parent with the chromosomes carrying the correct alleles. B) Which of the following gametes can the AaBb parent generate? C) For example progeny resulting from this cross, match the chromosomes as they would appear in a cell at G1, G2, and metaphase of mitosis.
- 26. Open EndedIn Drosophila melanogaster, white eye is an X-linked recessive trait, and red eye is an X-linked dominant trait. Assume that the flies have a diploid set of autosomes (2A). Allele Xw codes for white eye, and allele X codes for red eye. Label each of the genotypes with the expected sex and eye color. XX, XwX, XwY, XO, XwXY, XwXwX
- 27. Open EndedAn X-linked recessive gene causes red-green color blindness in humans. Suppose John and Cathy have normal color vision. After 10 years of marriage to John, Cathy has given birth to a color-blind daughter and a color-blind son. John filed for divorce, claiming that he is not the father of at least one of the children. Which of the following statements describes John's paternity claim?
- 28. Open EndedAlbinism is a recessive trait that prevents an animal from being able to produce certain pigments. Snowflake is the albino gray squirrel pictured below. This pedigree represents her family. What is snowflake's genotype? Based on Snowflake's genotype, what is the genotype of Squirrel C?
- 29. Open EndedBelow is a pedigree of a family with a rare genetic disorder. Use the pedigree to determine the mode of inheritance of the disorder.
- 30. Open EndedSuppose that in goats, an independently sorting autosomal allele that produces a bearded phenotype is dominant in males and recessive in females. The symbol B^b represents the bearded allele and B+ represents the beardless allele. The autosomal allele for a black coat (W), which also independently asserts, is dominant over the allele for white coat (w). Match each set of progeny phenotypes and proportions to the parental cross that produced that set. B+BbWw male * B+BbWw female B+BbWw male * B+Bbww female B+B+Ww male * BbBbWw female B+BbWw male * BbBbww female
- 31. Open EndedAn allelic series determines coat color in rabbits:C (full color), c^ch (chinchilla, gray color), c^h (Himalayan, white with black extremities), and c (albino, all white). The C allele is dominant over all others, c^ch is dominant over c^h and c, c^h is dominant over c, and c is recessive to all other alleles. This dominance hierarchy can be summarized as C>c^ch>c^h>c. The rabbits in the following table are crossed and produce the progeny shown. Match the parental genotypes to the letter corresponding to the appropriate cross listed in the table.
- 32. Open EndedA homozygous variety of opium poppy with lacerate leaves was crossed with another homozygous variety with normal leaves. All the F1 had lacerate leaves (jagged-edged leaves). Two F1 plants were crossed to produce the F2. Of the F2, 249 had lacerate leaves and 16 had normal leaves. How are lacerate leaves determined in the opium poppy? Give genotypes for all the plants in the P, F1, and F2 generations. Some generations will have more than one genotype.
- 33. Open EndedMale-limited precocious puberty results from a rare, sex-limited autosomal allele (P) that is dominant over the allele for normal puberty (p) and is expressed only in males. Bill undergoes precocious puberty, but his brother Jack and his sister Beth underwent puberty at the usual time, between the ages of 10 and 14. Although Bill's mother and father underwent normal puberty, his two maternal uncles underwent precocious puberty. All of Bill's grandparents underwent normal puberty. Match the most likely genotypes for each relative in his family below. Bill, Bill's brother Jack, Bill's sister Beth, Bill's father, Bill's mother, Bill's uncle, Bill's grandfather, Bill's grandmother
- 34. Open EndedA trait, such as height, has high heritability because much of the variation between individuals is the result of genetic variation. However, not all of the variation for height in a population can be attributed to genetic variation alone. Why does genetic variation not always determine the differences in a given trait between individuals?
- 35. Open EndedRed-green color blindness is an X-linked recessive trait. Heterozygous females have normal color vision but are carriers of the allele for red-green color blindness. Based on the information presented in the pedigree, select all of the females from the list below that are known carriers of red-green color blindness. 7, 13, 2, 23, or 10
- 36. Open EndedYou cross the fly with vestigial wings (tiny wings) to the fly with normal wings, the progeny is reared at 31 Celsius. What percentage of offspring have vestigial wings?
- 37. Open EndedPenile hypospadias, a birth defect in male humans in which the urethra opens on the shaft instead of at the top of the penis, results from an autosomal dominant gene in some families. Females who carry the gene show no effects. What type of trait is this birth defect an example of?
- 38. Open EndedAnn's family has a history of cystic fibrosis, a recessive genetic disease. In the pedigree below, family members who are afflicted with the disease are shown in red. Members who are unafflicted May or may not be carriers. Which of the given family members can be identified definitively as unafflicted carriers of cystic fibrosis? Female cousin, uncle, aunts husband, grandmother, and/or aunt
- 39. Open EndedWhat does each statement describe for a genetic screening procedure? (A) Identifies treatable genetic disorders soon after birth (B) identifies recessive disease carriers in a population (C) identifies genetic disorders in a developing fetus (D) identifies a genetic disease in a healthy, but high-risk, patient
- 40. Open EndedWhat is the main reason that geneticists devote so many resources to studying genetics in humans?
- 41. Open EndedAssume that long ear lobes in humans are an autosomal dominant trait that exhibits 30% penetrance. A person who is heterozygous for long ear lobes mates with a person who is homozygous for normal ear lobes. What is the probability that their first child will have long ear lobes? Use two decimal places for your answer.
- 42. Open EndedBelow is a pedigree of a family with a rare genetic disorder. Individual 11 is known to have no affected alleles. Use the pedigree to determine the mode of inheritance of the disorder.
- 43. Fill in the BlankEctrodactyly is a rare condition in which the fingers are absent and the hand is split. Ademar Freire-Maia reported the appearance of ectrodactyly in a family in Brazil, whose pedigree is shown here. Ectrodactyly inheritance is most likely _____________.
- 44. Open EndedHuntington's disease, which causes degeneration of neurons, runs in Maria's family. Huntington's is a heritable autosomal dominant genetic disease. In an autosomal dominant disease, only one abnormal allele is required to cause the disease in offspring. However, it is possible not all offspring will receive the abnormal allele from an affected heterozygous parent. Family members that have the disease include Maria's paternal grandmother and Maria's paternal uncles, Maria's paternal grandfather does not have the disease. Because symptoms of Huntington's disease do not appear until later in life, genetic testing is necessary to determine whether a younger individual possesses the allele for the disease. These tests determine that Maria's father does not carry the allele for Huntington's disease. Maria's maternal uncle suggested that Maria create a pedigree to track the disease in her family. Use the symbols provided to complete the pedigree.
- 45. Open EndedSuppose two independently assorting genes are involved in the pathway that determines fruit color in squash. These genes interact with each other to produce the squash colors seen in the grocery store. At the first locus, the W allele codes for a dominant white phenotype, whereas the w allele codes for a colored squash. At the second locus, the allele Y codes for a dominant yellow phenotype, and the allele y codes for a recessive green phenotype. The phenotypes from the first locus will always mask the phenotype produced by the second locus if the dominant allele (W) is present at the first locus. This masking pattern is known as dominant epistasis. A dihybrid squash, WwYy, is selfed, and produces 320 offspring. How many offspring are expected to have each of the following phenotypes?
- 46. Open EndedSuppose concordance data were collected from a cohort study of twins to study the genetic contribution to the onset of type 1 diabetes, also called juvenile diabetes. Both monozygotic (identical) twins and dizygotic (fraternal) twins who grew up together in the same household were included. The concordance rate was found to be 68% among monozygotic twin pairs and 11% in dizygotic twin pairs. What general conclusion about type 1 diabetes can be drawn from these results?
- 47. Open EndedA man with a specific unusual genetic trait marries an unaffected woman. For each type of inheritance, place the pedigree that would result from the cross. Assume the trait is fully penetrant and rare. Inheritances: Autosomal recessive, X-linked recessive, Y-linked, autosomal dominant, and X-linked dominant
- 48. Open EndedA maternal effect can cause the offspring phenotype ratio to depart from that of classic Mendelian inheritance. In a species of snail, the dominant allele N codes for right-handed shell coiling and recessive allele n codes for left-handed shell coiling. If an Nn female with right-handed shell coiling mates with an nn male, what is the shell coiling phenotypic ratio of their offspring?
- 49. Open EndedSuppose that allele D produces small fingers and allele d produces normal fingers. A heterozygous male with the Dd genotype mates with a homozygous female with the dd genotype. Small fingers is an autosomal dominant trait expressed with 30% penetrance. Determine the probability that their offspring will have small fingers. Report your answer as a percentage without decimal points.
- 50. Open EndedThe dominance pattern of a gene can be determined from the phenotypes of the parents and offspring. In the examples below, assume that each parent is homozygous for the specific allele and that the progeny are heterozygous. Classify each example as either complete dominance, incomplete dominance, or codominance. (A) A mother with straight hair and a father with curly hair have a son with wavy hair. (B) A pea plant with smooth seeds and a pea plant with wrinkled seeds produce a pea plant with smooth seeds. (C) A mother with type A blood and a father with type B blood have a daughter with type AB blood. (D) A white cow and a red bull have a calf that is white with red spots (roan colored). (E) A red snapdragon and a white snapdragon produce a pink snapdragon.
- 51. Open EndedSuppose that various members of a family spanning four generations have a mutant phenotype that is very rare in the general population. The affected individuals are shown in the pedigree below. What is the most likely mode of inheritance for this rare phenotype?
- 52. Open EndedSuppose a particular species of tulip plant has three alleles for the gene that codes for flower color. The C^R allele produces red tulips, the C^p allele produces purple tulips, and the C^w allele produces white tulips. C^R is donant over C^p and C^w, and C^p is dominant over C^w. For each of the following crosses, determine the expected ratio of offspring for each flower color. (C^R C^p) x (C^p C^w) (C^R C^w) x (C^p C^w)
- 53. Open EndedSuppose that Jess has myotonic dystrophy and shows traits such as uncontrolled muscle activity. Jess's mother, Rose, is dystrophic, but her father is normal. Jess is married to Dave, and Dave is normal. Jess and Dave have a daughter, Lisa, and two sons, Phil and Erik. Lisa and Phil are normal, but Erik is dystrophic. Jess's sister, Jill, is normal. Jill's husband and their only child are also normal. Jess's brother, Pete, is dystrophic, and has three children with Mary, who is normal. Pete and Mary have two daughters, Sandy and Judy, as well as a son, Carl. Sandy is normal, but Judy and Carl are dystrophic. The image below is the pedigree of Jess's family. Label the pedigree symbols with the corresponding names of the individuals in Jess's family.
- 54. Open EndedHow are mitochondrial genes typically inherited?
- 55. Open EndedRed-green color blindness is a human X-linked recessive disorder. The normal allele, XB, is dominant to the mutant allele, Xb. Jill has normal color vision, but her father is color blind. Jill marries Tom, who also has normal color vision. Jill and Tom have a daughter who has Turner syndrome and is color blind. How and from whom did the daughter inherit color blindness?
- 56. Open EndedSelect the definition of polyploidy.
- 57. Open EndedWhich statement explains why the recombination frequency between two genes is always less than 50%?
- 58. Open EndedIn each of the following scenarios, an individual heterozygous for the indicated gene or genes is crossed with an identical heterozygous individual. Predict the number of different phenotypes that would be observed among the progeny of such a cross.
- 59. Open EndedA geneticist is using a three-point testcross to map three linked Drosophila recessive mutations called a, b, and c, where a is associated with anomalous gait; b is associated with buckled wings; and c is associated with curved bristles. She first crosses homozygous anomalous, buckled flies to homozygous curved flies. Next, she testcrosses the F1 progeny to anomalous, buckled, curved flies. She obtains 1000 progeny distributed as the following results. From this data, calculate the map distance between a and c.
- 60. Open EndedDuring meiosis, errors can occur during chromosome replication. Which term describes the addition of genetic material to a chromosome through extra replication of a chromosomal section?
- 61. Open EndedMatch the definitions to the appropriate terms that describe the number of chromosomes (haploid, monosomic, n=1). -A genome composed of one unique chromosome - a single unpaired copy of each chromosome - only one copy of a specific chromosome
- 62. Open EndedA researcher uses generalized transduction to map three bacterial genes. She collects the phage lysates of a donor strain with genotype leu+ phe+ lys+, and uses them to infect a recipient strain that is leu- phe- lys-. Rates of cotransduction for leu+ are reported (refer to image). Determine whether phe or lys is physically closest to leu and provide justification.
- 63. Open EndedThe following is a representation of a human karyotype. What type of genetic disorder is shown in this karyotype?
- 64. Open EndedA cross is performed with Drosophila melanogaster, and data are collected for a large number of F2 progeny. The data from two three-point crosses are separated into the two tables below using a random gene order. Each gene symbol alone represents a mutant animal, and the superscript plus represents an animal with the wild-type phenotype. A dominant marker gene, differentiated by its capital notation, is contained in one table. The location of the marker on the chromosome is known and has already been placed on the map. Using the data below, order the remaining three unknown genes in relation to the marker. Marker gene- L
- 65. Open EndedAssume that the autotriploid cell in the image has 3n= 30 chromosomes. For each of the gametes produced by this cell, what would the chromosome number of the resulting zygote be if the gamete fused with a normal haploid gamete? (Options are 0, 10, 20, 30, 40, 50)
- 66. Open EndedEach image depicts a type of gene transfer. Match the term for the type of gene transfer that each image depicts. Not all terms will be placed. Transformation, vertical gene transfer, conjugation, transduction
- 67. Open EndedTwo mutations that affect plaque morphology in phases (a- and b-) have been isolated. Phages carrying both mutations (a-b-) are mixed with wild-type phages (a+b+) and added to a culture of bacterial cells. Subsequent to infection and lysis, samples of the phage lysate are collected and cultured on bacterial cells. The following numbers of plaques are observed in the table. Using the data, calculate the recombination frequency between the a and b genes.
- 68. Open EndedSuppose a geneticist uses a three-point testcross to map three recessive, linked hummingbird wing-shape mutations called tk, r, and b, where tk is associated with thick wings; r is associated with round wings; and b is associated with blunt wings. He first crosses homozygous blunt birds to homozygous thick, round birds. Next, he testcrosses the F1 progeny to thick, round, blunt birds. He obtained the following results. Given this data, label the progeny phenotypic classes as either parental, single crossover (SCO), or double crossover (DCO) recombinant types. Each label may be used multiple times. Given: thick, blunt is SCO; and thick, round, blunt is SCO
- 69. Open EndedThe genetic map (image) shows the location of three genes on a chromosome. Order the gene pairs based on their likelihood of recombining from most likely to least likely to recombine.
- 70. Open EndedSuppose a researcher conducts matings between three Hfr bacterial strains and an F- strain. The table below show the order in which genes are incorporated for each strain. Determine the gene order of the chromosome by placing each gene on the outside of the circular chromosome map. Label the origin of replication for each Hfr strain on the inside of the map to indicate polarity of the origin.
- 71. Open EndedUsing the figure, identify which gene on the F factor will be transferred last in strain Hfr5.
- 72. Open EndedTwo brothers have X-linked red-green colorblind vision, and their parents have normal color vision. The first brothers karyotype is 47,XXY (Klinefelter syndrome), and the second brother's karyotype is 46,XY. In which parent and in what cell division phase did the first brother's chromosomal nondisjunction occur? Assume no recombination.
- 73. Open EndedWhat information about recombination frequencies enables scientists to create linkage maps?
- 74. Open EndedSuppose DNA from a strain of Bacillus subtilis with the genotype a+b+c+d+e+ was used to transform a strain with the genotype a-b-c-d-e-. The pairs of genes were then checked for cotransformation and the data below was collected. Using the data, determine the gene order of the bacterial chromosome below. (b+ end—> end of chromosome)
- 75. Open EndedA man has a large inversion on one of his chromosomes. How might this impact his offspring?
- 76. Fill in the BlankFrank has Klinefelter syndrome (47, XXY). His mother has normal skin, but his father has anhidrotic ectodermal dysplasia, an X-linked condition where the skin does not contain sweat glands. Frank has patches of normal skin and patches of skin without sweat glands. Complete the sentence. Frank received the mutant chromosome from his ____________. Nondisjunction occurred in his _________ during the ____________ Meiotic division.
- 77. Open EndedIn beetles, the gene for color and the gene for pattern are located on the same chromosome and exhibit recombination. The lined pattern allele (l) is recessive to the solid unpatterned allele (L), and the aqua color allele (b) is recessive to the blue color allele (B). Geneticists cross a homozygous lined aqua beetle with a homozygous solid blue beetle. They then carry out a testcross using the F1 progeny. The parental chromosomes for the testcross are shown. Identify all possible gametic haplotypes each parent can form.
- 78. Open EndedIn the fruit fly, Drosophila melanogaster, a known deletion on the X chromosome removes both a gene involved in the fly's development and the gene for eye color. The deletion is lethal when homozygous or hemizygous. Flies that are heterozygous for the mutation are viable, but have indentations at the wing margin. Therefore, the deletion is named the Notch mutation. The allele for wild type eyes is dominant over the allele for white eyes. Predict the phenotypic ratio of the offspring from a cross between a white-eyed notched female and a wild type male.
- 79. Open EndedFamilial Down syndrome is similar to primary Down syndrome in that it is caused by trisomy 21. However, in familial Down syndrome, all or part of the third copy of chromosome 21 has translocated onto another autosome, typically chromosome 14. In cases of familial Down syndrome, one of the parents of the affected child is often a carrier of a translocated chromosome. The translocation carrier parents does not have Down syndrome because he or she has a total of two copies of chromosome 21. Suppose that a woman is a translocation carrier of chromosome 21 on chromosome 14. She conceives six zygotes with a normal man who carries no aneuploidies. Match the description of the chromosomes inherited by each zygote with the viability of the zygote.
- 80. Open EndedThe following diagram represents a normal wild-type chromosome. Below this diagram is the same chromosome in which a chromosomal mutation has occurred. Place the type of chromosomal mutation next to each set of chromosomes. The • represents the centromere. Wild-type Chromosome AB•CDEFG Mutation 1- AB•CDEFDEFG Mutation 2- AB•DEFCDEFG Mutation 3- AB•CDE Mutation 4- AB•CGFED Mutation 5- AEDC•BFG
- 81. Open EndedSome people with Turner syndrome are 45,X/46,XY mosaics. How could this mosaicism arise?
- 82. Open EndedAbout 0.3% of human live births are trisomic. In contrast, only 0.02% of human live births are monosomic. Select the best explanation for why the occurrence of trisomics is greater than that of monosomics.
- 83. Open EndedIn the snail Cepaea nemoralis, an autosomal allele causing a banded shell, u, is recessive to the allele for an unbanded shell, U. Genes at a different locus determine the background color of the shell. The allele for a yellow shell, b, is recessive to the allele for a brown shell, B. A banded, yellow snail is crossed with a homozygous brown, unbanded snail. The F1 progeny are then crossed with banded, yellow snails in a testcross. Predict the percentage of progeny in each phenotype if the two genes are linked with no recombination, if the two genes assort independently, and if the genes are 20 m.u. apart. Place the percentage for each phenotype for each of the scenarios in the table below. Percentages can be used more than once. Brown, unbanded Brown, banded Yellow, unbanded Yellow, banded
- 84. Open EndedCrossing over within a pericentric inversion produces chromosomes that have extra copies of some genes and no copies of other genes. The fertilization of gametes containing these duplication or deficient chromosomes often results in children with syndromes characterized by developmental delay, mental retardation, abnormal development of organ systems, and early death. One study examined individual sperm cells of a male who was heterozygous for a pericentric inversion on chromosome 8 and determined that crossing over took place within the pericentric inversion in 26% of the meiotic divisions. Assume that a man and a woman are phenotypically normal, but the woman is heterozygous for a pericentric inversion on chromosome 8. The man is karyotypically normal. What is the probability that this couple's child will inherit a duplicated or deficient chromosome 8 that results from crossing over within this pericentric inversion?
- 85. Open EndedThree pairs of bacterial cells with the genotypes listed below undergo conjugation. A) What are the genotypes of each cell after conjugation: F+ x F- Hfr x F- F' x F- B) What is the role of the F-factor in conjugation?
- 86. Open EndedIf an F1 plant, which is the progeny of RR and rr plants, is backcrossed to the parent with round seeds, what proportion of the progeny will have wrinkled seeds? (Use a Punnett square.)
- 87. Open EndedIf the probability of being blood-type A is 1/8 and the probability of blood-type O is ½, what is the probability of being either blood-type A or O?
- 88. Open EndedThe following two genotypes are crossed Aa Bb Cc dd Ee x Aa bb Cc Dd Ee. What is the probability of having a Aa bb Cc dd ee progeny?
- 89. Open EndedIn Mendel's pea plants, how did he know that each F1 generation contained two alleles encoding different characteristics?
- 90. Open EndedPhenylketonuria (PKU) is a disease that results from a recessive gene. Two normal parents produce a child with PKU. What is the probability that an egg from the mother will contain the PKU allele?
- 91. Open EndedIn cats, curled ears result from an allele (Cu) that is dominant over an allele (cu) for normal ears. Black color results from an independently assorting allele (B) that is dominant over an allele for gray (b). A gray cat homozygous for curled ears is mated with a homozygous black cat with normal ears. All the F1 cats are black and have curled ears. An F1 cat mates with a stray cat that is gray and possesses normal ears. What phenotypes and proportions of progeny are expected from this cross?
- 92. Open EndedHow does the heterogametic sex differ from the homogametic sex?
- 93. Open EndedIf an XY individual has a defective androgen receptor what external characteristics would the person exhibit?
- 94. Open EndedIf an XX individual has a defective androgen receptor what external characteristics would the person exhibit?
- 95. Fill in the BlankA fruitfly is found that has three sex chromosomes (XXY) and three of each autosome. The sex of this fruitfly is _________ because ___________.
- 96. Open EndedRed-green color blindness is an X-linked recessive trait in humans. Polydactyly (extra fingers and toes) is an autosomal dominant trait. Martha has normal fingers and toes and normal color vision. Her mother is normal in all respects, but her father is color blind and polydactylous. Bill is color blind and polydactylous. His mother has normal color vision and normal fingers and toes. If Bill and Martha marry, what proportions of children with specific phenotypes would they be expected to produce? (The answers only include the proportions of some of the possible phenotypes; other phenotypes are also expected to occur but are not included.)
- 97. Open EndedHow many Barr bodies are present in an individual with Klinefelter syndrome (XXYY)?
- 98. Fill in the BlankThe allele H codes for LDL receptors that are needed to metabolize LDL. People who are HH have healthy levels of LDL, whereas those who are hh have dangerous levels of cholesterol that often lead to heart attacks and death during childhood. Interestingly, those who are Hh have high levels of cholesterol and are at risk of a heart attack as a young adult, but if their cholesterol is managed, they will have a long life. This is an example of _______.
- 99. Open EndedA woman has blood type AM. She has a child with blood-type AB MN. M and N are co-dominant at a locus different than A and B. Which of the following blood types could not be that of the child's father and why? George- O N Tom- AB MN Bill- B MN Claude- A N Henry- AB M
- 100. Open EndedAssume that long fingers are inherited as a recessive trait with 80% penetrance. Two people heterozygous for long fingers mate. What is the probability that their first child will have long fingers?
- 101. Open EndedThe difference between dominance and epistasis is that:
- 102. Open EndedIn the yawncat (a rare hypothetical animal), the dominant allele R causes solid tail color, and the recessive allele r results in white spots on a colored background. The black coat color allele B is dominant to the brown allele b, but these genes can only be expressed if the animal has an mm genotype at a third gene locus. Animals that are M_ are yellow regardless of which allele from the B locus is present. A mating between a solid yellow-tailed male yawncat and a solid brown-tailed female yawncat produces 16 offspring with the following tail phenotypes: six solid yellow, two spotted yellow, three solid black, one spotted black, three solid brown, and one spotted brown. What is the most likely genotype of the male parent?
- 103. Open EndedSuppose that the "fabulous" phenotype is controlled by two genes, A and B, as shown in the diagram below. Allele A produces enough enzyme 1 to convert "plain" to "smashing." Allele a produces no enzyme 1. Allele B produces enough enzyme 2 to convert "smashing" to "fabulous." Allele b produces no enzyme 2. The A and B genes are both autosomal and assort independently. Plain --> enzyme 1--> smashing --> smashing --> enzyme 2--> fabulous What will be the phenotype(s) of the F1 offspring of a true-breeding "fabulous" father and a true-breeding "plain" mother (aa bb)?
- 104. Open EndedIn domestic chickens, some males display a plumage pattern called cock feathering. Other males and all females display a pattern called hen feathering. Cock feathering is an autosomal recessive trait that is exhibited in males only. Two heterozygous birds are mated. A) What fraction of the male offspring is expected to exhibit cock feathering? B) What fraction of the total offspring is expected to exhibit cock feathering?
- 105. Open EndedMale-limited precocious puberty results from a rare autosomal allele (P) that is dominant over the allele for normal puberty (p) and is expressed only in males. A male and female that both went through normal puberty have two sons. The first son undergoes precocious puberty but the second undergoes normal puberty. A) What is the genotype of the mother? B) What is the genotype of the father?
- 106. Open EndedThe bicoid mutation (bcd−) in fruit flies is inherited as a maternal effect recessive allele. What is the expected ratio of phenotypes in the offspring of a cross between a bcd+/bcd− female and a bcd+/bcd− male?
- 107. Open EndedAutosomal recessive traits often appear in pedigrees in which there have been consanguine mating (related individuals), because these traits:
- 108. Open EndedHow could you distinguish between an autosomal recessive trait with higher penetrance in males and an X-linked recessive trait?
- 109. Open EndedThe following pedigree illustrates the inheritance of Nance-Horan syndrome, a rare genetic condition in which affected persons have cataracts and abnormally shaped teeth. A) On the basis of this pedigree, what is the most likely mode of inheritance of Nance-Horan syndrome? B) If III-2 and III-7 were to mate, what is the probability that their first child would have Nance-Horan syndrome?
- 110. Open EndedThe following pedigree illustrates the inheritance of ringed hair, a rare condition in which each hair is differentiated into light and dark zones. What mode of inheritance is most likely for the ringed-hair trait in this family?
- 111. Open EndedWhich mode(s) of inheritance explain the pattern of occurrence of a rare trait in the pedigree below?
- 112. Open EndedWhy would an autosomal dominant, sex-limited to males mode of inheritance best explain the pattern of occurrence of a rare trait in the pedigree below?
- 113. Open EndedFor single crossovers, the frequency of recombinant gametes is half the frequency of crossing over because:
- 114. Open EndedAssume that you wish to determine if two genes are linked or not. You are going to analyze the progeny of a genetic cross to determine this. Which of the following crosses will MOST easily yield offspring that will allow you to determine if the two genes are linked or not?
- 115. Open EndedIn German cockroaches, bulging eyes (bu) are recessive to normal eyes (bu+) and curved wings (cv) are recessive to straight wings (cv+). Both traits are encoded by autosomal genes that are linked. A cockroach has genotype bu+ bu cv+ cv, and the genes are in repulsion. Which of the following sets of genes will be found in the most common gametes produced by this cockroach?
- 116. Open EndedConsider a cross between individuals who are AABB x aabb. The F1 progeny have genotype AaBb. When the F1 progeny produce gametes, which of the following would be considered recombinant gametes?
- 117. Open EndedIf a heterozygous parent (AB/ab) is test-crossed to a homozygous recessive (ab/ab), what will the progeny phenotypic ratio be if genes A and B are not linked?
- 118. Open EndedThe following testcross produces the progeny shown: RrTt x rrtt --> 10 RrTt, 40 rrTt, 40 Rrtt, and 10 rrtt A) What is the percent recombination between the R and T loci? B) Were the genes in RrTt parent in coupling or repulsion?
- 119. Open EndedIn a three-point testcross the nonrecombinant progeny are A+ B+ C+ and a b c. The double-crossover progeny are a B+ C+ and A+ b c. Which locus (A, B, or C) is in the middle?
- 120. Open EndedWhat is the most likely order of the linked genes R, S, and T if the distance between R and S is 8 m.u., the distance between S and T is 14 m.u., and the distance between R and T is 22 m.u.?
- 121. Open EndedYou have determined that the gene order for three linked genes being studied is A B C. The number of recombinants resulting from crossover between genes A and B alone totals 27 and 32, while the double-crossover progeny total 3 and 5. What is the recombination frequency between genes A and B if the total number of progeny from the cross is 1000?
- 122. Open EndedConsider the follow three-point cross: A B C x a b c ———- ———— a b c a b c Which of the following is NOT a possible progeny genotype? (Consider both recombinant and non-recombinant progeny.)
- 123. Open EndedA duplication of the Bar region leads to a decrease in eye size. A) What type of dominance does the Bar mutation cause? B) The Bar duplication is on the X chromosome, which phenotype would a male with a Bar duplication look like?
- 124. Open EndedWhich is NOT a way that deletions can cause abnormal phenotypes?
- 125. Open EndedA dicentric chromosome can be produced for which type of chromosome rearrangement, include the effects of crossing over?
- 126. Open EndedDoes the individual with this karyotype have Down syndrome?
- 127. Open EndedA diploid species has a total of 46 chromosomes. How many chromosomes would be found in a monosomy, trisomy, and autotriploid?
- 128. Open EndedGenetic exchange in bacteria follows one of three mechanisms (conjugation, transformation, and transduction). What is true regarding these three mechanisms?
- 129. Open EndedConjugation between F' and F- cell usually results in:
- 130. Open EndedWhich gene is transferred third from this F factor?
- 131. Open EndedIn a gene mapping experiment, DNA from a strain that is gal+ pro+ lac+ is transformed into an E. coli that is gal − pro − lac −. Some resulting transformants are gal+ lac+ and some are pro+ gal+, but no transformants are lac+ pro+. Which gene is in the middle?
- 132. Open EndedDNA from a bacterial strain that is his+ leu+ lac+ is used to transform a strain that is his- leu- lac-. The following percentages of cells were transformed: Based on this information, what is the order of these three genes on the chromosome in the donor strain?
- Answer choicesTagsAnswer choicesTags