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Chapter 15: The Chromosomal Basis of Inheritance
 
Chapter Quiz
 

Chapter Quiz


1 .       The chromosome theory of inheritance states that _____. (Concept 15.1E-Book) [Hint]

 genes occupy specific positions on chromosomes
 homologous chromosomes segregate from each other during meiosis
 chromosomes assort independently during meiosis
 The first and second answers are correct.
 The first, second, and third answers are correct.
2 .       Drosophila is a useful organism for genetic studies for all of the following reasons except _____. (Concept 15.1E-Book) [Hint]

 They have a long generation time.
 A single mating can produce many offspring.
 They have a small number of chromosomes.
 Drosophila chromosomes can be easily distinguishable under a light microscope.
 All of the above.
3 .       Wild type refers to _____. (Concept 15.1E-Book) [Hint]

 the most common phenotype in the natural population
 the most extreme mutant phenotype observed in an experiment
 any mutant genotype
 a kind of chromosomal deletion
 extranuclear genes
4 .       Which of the following statements about Thomas Hunt Morgan's experiments with white-eyed mutant flies is incorrect? (Concept 15.1E-Book) [Hint]

 In the parental cross, a white-eyed male was crossed with a red-eyed female. The F1 progeny all had red eyes.
 The F1 flies were crossed with each other, and the F2 progeny included red-eyed and white-eyed flies in a 3:1 ratio.
 Among the F2 progeny, half of the males had white eyes.
 Among the F2 progeny, half of the females had white eyes.
 All of the above are incorrect.
5 .       If two genes are linked, _____. (Concept 15.2E-Book) [Hint]

 they are on different chromosomes
 they assort independently
 they code for the same protein
 they are on the same chromosome
 they are on sex chromosomes
6 .       In a particular species of mammal, black hair (B) is dominant to green hair (b), and red eyes (R) are dominant to white eyes (r). When a BbRr individual is mated with a bbrr individual, offspring are produced in a ratio of 5 black hair and red eyes:5 green hair and white eyes:1 black hair and white eyes:1 green hair and red eyes. Which of these explanations accounts for this ratio? (Concept 15.2E-Book) [Hint]

 Green-haired individuals have a higher prenatal mortality than black-haired individuals.
 The genes for hair color and the genes for eye color are carried on different chromosomes.
 The expected results did not take genetic recombination into account.
 The genes for both of these traits are carried on the autosomes.
 The genes for hair color and eye color are linked.
7 .       A gray-bodied, vestigial-winged fly is crossed with a black-bodied, normal-winged fly. The F1 progeny is testcrossed. Among the resulting offspring, _____ is a parental type, and _____ is a recombinant type. (Concept 15.2E-Book) [Hint]

 gray-bodied, normal-winged ... black-bodied, vestigial-winged
 gray-bodied, vestigial-winged ... black-bodied, normal-winged
 gray-bodied, normal-winged ... black-bodied, normal-winged
 black-bodied, normal-winged ... black-bodied, vestigial-winged
 black-bodied, normal-winged ... black-bodied, normal-winged
8 .       You perform a testcross using F1 dihybrid flies. If, in the resulting offspring, the percentages of parental and recombinant offspring are about the same, this would indicate that the two genes are _____. (Concept 15.2E-Book) [Hint]

 linked
 unlinked
 similar in DNA sequence
 mutated
 imprinted
9 .       The recombination frequency between two gene loci is _____. (Concept 15.2E-Book) [Hint]

 dependent on the sex of the parent
 greater as the distance between the two loci increases
 greater as the distance between the two loci decreases
 dependent on whether dominant or recessive alleles are carried at the two loci
 equal to the size of the chromosome
10 .       Four genes (A, B, C, and D) are on the same chromosome. The recombination frequencies are as follows: A-B: 19%; B-C: 14%; A-C: 5%; B-D: 2%; A-D: 21%; C-D: 16%. Based on this information, which sequence of genes is correct? (Concept 15.2E-Book) [Hint]

 ABCD
 ABDC
 ACBD
 ACDB
 ADBC
11 .       In question 6, the observed distribution of offspring was as follows: black-red 1,070; black-white 177; green-red 180; green-white 1,072. Based on these data, what is the recombination frequency? (Concept 15.2E-Book) [Hint]

 86%
 7%
 approximately 17%
 approximately 14%
 30%
12 .       A linkage map _____. (Concept 15.2E-Book) [Hint]

 orders genes on a chromosome based on recombination frequencies
 can be constructed only for sex chromosomes
 orders genes on a chromosome based on their location with respect to a stained band
 shows the ordering and exact spacing of genes on a chromosome
 predicts the probability that you will have a male or female child
13 .       Because the frequency of crossing over is not uniform along the length of a chromosome, _____. (Concept 15.2E-Book) [Hint]

 the recombination frequency between two genes cannot be used to calculate the number of map units separating them
 map units do not necessarily correlate to physical distances along the chromosome
 pairs of homologous chromosomes contain small but significant differences in gene order
 the centimorgan is an unreliable unit of measurement, and is rarely used today
 recombination frequency cannot be used to determine the number of centimorgans separating two genes
14 .       Linked genes can be separated by anywhere from _____ to _____ centimorgans. (Concept 15.2E-Book) [Hint]

 0 ... 100
 50 ... 100
 0 ... 25
 0 ... 50
 25 ... 50
15 .       What is the probability that a male will inherit an X-linked recessive allele from his father? (Concept 15.3E-Book) [Hint]

 0%
 25%
 50%
 75%
 100%
16 .       In an X-linked, or sex-linked, trait, it is the contribution of _____ that determines whether a son will display the trait. (Concept 15.3E-Book) [Hint]

 the mother
 the father
 the paternal grandmother
 the paternal grandfather
 none of the above
17 .       If a mother is heterozygous for a recessive sex-linked trait and her husband has the dominant allele, which one of the following is true about the probabilities for their children? (Concept 15.3E-Book) [Hint]

 All of their sons will have the recessive trait.
 Half of their sons will have the recessive trait.
 None of their sons will have the recessive trait.
 All of their daughters will be heterozygous.
 None of the above.
18 .       In werewolves, pointy ears (P) is dominant over round ears (p). The gene is on the X chromosome. (Sex determination in werewolves is the same as for "other" humans.) A certain female werewolf has pointy ears even though her father had round ears. What percentage of her sons will have round ears if she marries a werewolf with round ears? (Concept 15.3E-Book) [Hint]

 0%
 25%
 50%
 75%
 100%
19 .       A woman is red-green color-blind. What can we conclude, if anything, about her father? (Concept 15.3E-Book) [Hint]

 We have too little information to tell.
 There is a 50% probability that he has normal vision.
 He is red-green color-blind.
 He has two Y chromosomes.
 None of the above.
20 .       A woman is a carrier for red-green color blindness, a sex-linked trait. Her husband is normal (not color-blind) for this trait. What are the chances that their newborn daughter will be red-green color-blind? (Concept 15.3E-Book) [Hint]

 0%
 25%
 50%
 75%
 100%
21 .       Duchenne muscular dystrophy is caused by a sex-linked recessive allele. Its victims are almost invariably boys, who usually die before the age of 20. Why is this disorder almost never seen in girls? (Concept 15.3E-Book) [Hint]

 Sex-linked traits are never seen in girls.
 The allele is carried on the Y chromosome.
 Nondisjunction occurs in males but not in females.
 To express an X-linked recessive allele, a female must have two copies of the allele.
 A sex-linked allele cannot be passed from mother to daughter.
22 .       Hemophilia is a sex-linked disorder. The daughter of a father with hemophilia and a carrier mother has a _____ probability of having hemophilia. (Concept 15.3E-Book) [Hint]

 100%
 25%
 50%
 0%
 33%
23 .       Queen Victoria was a carrier of a recessive sex-linked allele for hemophilia. Which one of the following possibilities could explain the presence of the hemophilia allele in her genotype? (Concept 15.3E-Book) [Hint]

 Either her mother was a carrier or her father had hemophilia.
 Either her mother was homozygous dominant or her father had hemophilia.
 Both her mother and her father had hemophilia.
 Either her mother was a carrier or her father had a dominant allele.
 None of the above.
24 .       In a certain fish, fin rays (supporting structures for the fins) can be either bony or soft in adult fish. Sex linkage in a fish is similar to that in humans. What evidence would most strongly support the idea that the ray locus is on the X chromosome? (Concept 15.3E-Book) [Hint]

 Bony ray males can pass on bony rays only to their male offspring.
 Matings of soft ray males and bony ray females give different results from the matings of bony ray males and soft ray females.
 Females with either bony or soft rays can reproduce, but males with soft rays cannot transfer sperm to the female.
 Females with bony rays cannot pass bony rays to female offspring even if they are mating with a bony ray male.
 All of the above.
25 .       A genetic defect in humans results in the absence of sweat glands in the skin. Some men have this defect all over their bodies, but in women it is usually expressed in a peculiar way: A woman with this defect typically has small patches of skin with sweat glands and other patches without sweat glands. In women, the pattern of sweat-gland distribution can best be explained by _____. (Concept 15.3E-Book) [Hint]

 a mutation
 X chromosome inactivation
 RNA splicing
 an operon
 a homeobox
26 .       With a microscope, you examine some somatic cells from a woman and notice that each nucleus has two Barr bodies. What can you infer about the sex chromosomes in this individual? (Concept 15.3E-Book) [Hint]

 She is XX.
 She is XXX.
 She is XXXX.
 She is XXY, but the Y chromosome lacks the SRY gene.
 None of the above.
27 .       During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as _____. (Concept 15.4E-Book) [Hint]

 cellular sterility
 meiotic failure
 gametic infertility
 nondisjunction
 sticky chiasmata
28 .       In Klinefelter syndrome, individuals are phenotypically male, but they are tall and thin, have a female-like development of the hips and breasts, and have testes that remain in the abdomen instead of descending into the scrotum. The cells of Klinefelter individuals have two X chromosomes and one Y (they are XXY instead of XY). That is, Klinefelter syndrome is a(n) _____. (Concept 15.4E-Book) [Hint]

 translocation
 polyploidy
 aneuploidy
 duplication
 monosomy
29 .       Cells that have more than two complete sets of chromosomes are termed _____. (Concept 15.4E-Book) [Hint]

 aneuploid
 diploid
 polyploid
 nanoploid
 trisomy
30 .       _____ is usually less severe than _____, and _____ species have been observed in plants, fish, amphibians, and even mammals. (Concept 15.5E-Book) [Hint]

 Polyploidy ... aneuploidy ... polyploid
 Aneuploidy ... polyploidy ... aneuploid
 Monosomy ... trisomy ... monosomic
 Trisomy ... monosomy ... trisomic
 Nondisjunction ... disjunction ... nondisjunctional
31 .       Gene A is normally found on chromosome number 15 in humans. If amniocentesis reveals fetal cells containing gene A on chromosome 17, but not on 15, the best explanation would be that _____. (Concept 15.4E-Book) [Hint]

 crossing over occurred during synapsis of meiosis I in one parent's gametes
 base substitution occurred either during gametogenesis or in the mitotic divisions following fertilization
 an inversion of gene A occurred on chromosome 15
 translocation occurred
 at least one parent probably had a genetic syndrome
32 .       The exchange of segments between nonhomologous chromosomes is called _____. (Concept 15.4E-Book) [Hint]

 inversion
 translocation
 transduction
 transformation
 duplication
33 .       Why are individuals with an extra chromosome 21, which causes Down syndrome, more numerous than individuals with an extra chromosome 3 or chromosome 16? (Concept 15.4E-Book) [Hint]

 There are probably more genes on chromosome 21 than on the others.
 Chromosome 21 is a sex chromosome, and 3 and 16 are not.
 Down syndrome is not more common, just more serious.
 Extra copies of the other chromosomes are probably fatal to the developing embryo.
 Nondisjunction of chromosomes 3 and 16 probably occurs much less frequently.
34 .       When a person has Down syndrome, he or she has an extra chromosome 21. Therefore, Down syndrome is a kind of _____ and results from _____. (Concept 15.4E-Book) [Hint]

 aneuploidy ... nondisjunction of chromosome 21 during meiosis I
 polyploidy ... occurrence of meiosis without cytokinesis
 genomic imprint ... excessive methylation of either the paternal or maternal chromosome 21
 replication error ... an extra cycle of DNA synthesis during the S phase
 none of the above
35 .       A person with two X chromosomes and one Y chromosome would appear to be _____. (Concept 15.4E-Book) [Hint]

 male
 female
 both male and female
 neither male nor female
 any of the above, depending on the number of other chromosomes
36 .       Which one of the following is the only known viable human monosomy? (Concept 15.4E-Book) [Hint]

 XYY
 XO
 YO
 XY
 XXY
37 .       Which type of chromosomal alteration is responsible for the disorder cri du chat? (Concept 15.4E-Book) [Hint]

 inversion
 duplication
 genetic imprinting
 deletion
 translocation
38 .       Which of the following statements about genomic imprinting is incorrect? (Concept 15.5E-Book) [Hint]

 It silences the expression of certain genes in females, but not in males.
 It affects genes on both the sex chromosomes and the autosomes.
 It affects the expression of alleles depending on whether they are inherited from the mother or the father.
 It involves reversible chemical modifications to the DNA such as methylation.
 None of the above.
39 .       Both chloroplasts and mitochondria _____. (Concept 15.5E-Book) [Hint]

 are found within the nucleus
 have linear DNA
 carry extranuclear genes
 are inherited from both parents
 display a Mendelian pattern of inheritance
40 .       It is proposed that a certain disorder affecting the inner ear is caused by mitochondrial DNA. Which of the following observations would be the most decisive evidence against this idea? (Concept 15.5E-Book) [Hint]

 Fathers with the disorder pass it on to all their children, but mothers with the disorder do not pass it along.
 Females and males have the disorder in equal numbers.
 Mothers pass the disorder on to their offspring, but fathers do not.
 The precise cause of the disorder is found to involve the nervous system.
 All of the above would be evidence against mitochondrial inheritance of this condition.





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