Concepts of Genetics, 11th Edition Klug, Cummings, Spencer & Palladino -Test Bank Instant Download - Complete Test Bank With Answers Sample Questions Are Posted Below Chapter 5 Chromosome Mapping in Eukaryotes 1) The term normally applied when two genes fail to assort independently is ________. A) discontinuous inheritance B) Mendelian …
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Concepts of Genetics, 11th Edition Klug, Cummings, Spencer & Palladino -Test Bank
Instant Download – Complete Test Bank With Answers
Sample Questions Are Posted Below
Chapter 5 Chromosome Mapping in Eukaryotes
1) The term normally applied when two genes fail to assort independently is ________.
Answer: C
Section: 5.2
2) Assume that a cross is made between AaBb and aabb plants and that all the offspring are either AaBb or aabb. These results are consistent with ________.
Answer: A
Section: 5.2
3) Assume that a cross is made between AaBb and aabb plants and that the offspring fall into approximately equal numbers of the following groups: AaBb, Aabb, aaBb, aabb. These results are consistent with ________.
Answer: A
Section: 5.2
4) Assume that a cross is made between AaBb and aabb plants and that the offspring occur in the following numbers: 106 AaBb, 48 Aabb, 52 aaBb, 94 aabb. These results are consistent with ________.
Answer: C
Section: 5.2
5) Assume that regarding a particular gene, one scored 30 second-division ascospore arrangements and 70 first-division arrangements in Neurospora. What would be the map distance between the gene and the centromere?
Answer: A
Section: 5.10
6) The phenomenon in which one crossover increases the likelihood of crossovers in nearby regions is called ________.
Answer: D
Section: 5.4
7) Which of the following methods is involved in determining the linkage group and genetic map in humans?
Answer: A
Section: 5.6
8) The genes for mahogany eyes and ebony body are approximately 25 map units apart on chromosome 3 in Drosophila. Assume that a mahogany-eyed female was mated to an ebony-bodied male and that the resulting F1 phenotypically wild-type females were mated to mahogany, ebony males. Of 1000 offspring, what would be the expected phenotypes, and in what numbers would they be expected?
Answer: mahogany = 375; ebony = 375; wild type = 125; mahogany-ebony = 125
Section: 5.2
9) Assume that there are 12 map units between two loci in the mouse and that you are able to microscopically observe meiotic chromosomes in this organism. If you examined 200 primary oocytes, in how many would you expect to see a chiasma between the two loci mentioned above?
Answer: 48
Section: 5.2
10) Draw a diagram of the chromosomal events that will ultimately result in the segregation of alleles (A and a) during meiosis II rather than meiosis I.
Answer:
Section: 5.2
11) Given that loci A and B in Drosophila are sex-linked and 20 map units apart, what phenotypic frequencies would you expect in male and female offspring resulting from the following crosses? (Assume A and B are dominant to a and b, respectively.)
(a) AaBb (cis) female × ab/Y male
(b) AaBb (trans) female × ab/Y male
(c) aabb female × AB/Y male
Answer:
(a) AB = 40; ab = 40; Ab = 10; aB = 10 (sexes have the same phenotypes)
(b) Ab = 40; aB = 40; AB = 10; ab = 10 (sexes have the same phenotypes)
(c) all males = ab; all females = AB
Section: 5.2
12) Phenotypically wild F1 female Drosophila, whose mothers had light eyes (lt) and fathers had straw (stw) bristles, produced the following offspring when crossed with homozygous light-straw males:
Phenotype Number
light-straw 22
wild 18
light 990
straw 970
Total 2000
Compute the map distance between the light and straw loci.
Answer: 2 map units
Section: 5.5
13) Assume that the genes for tan body and bare wings are 15 map units apart on chromosome #2 in Drosophila. Assume also that a tan-bodied, bare-winged female was mated to a wild-type male and that the resulting F1 phenotypically wild-type females were mated to tan-bodied, bare-winged males. Of 1000 offspring, what would be the expected phenotypes, and in what numbers would they be expected?
Answer: wild type = 425; tan-bare = 425; tan = 75; bare = 75
Section: 5.5
14) Assume that investigators crossed a strain of flies carrying the dominant eye mutation Lobe on the second chromosome with a strain homozygous for the second chromosome recessive mutations smooth abdomen and straw body. The F1 Lobe females were then backcrossed with homozygous smooth abdomen, straw body males, and the following phenotypes were observed:
smooth abdomen, straw body 820
Lobe 780
smooth abdomen, Lobe 42
straw body 58
smooth abdomen 148
Lobe, straw body 152
(a) Give the gene order and map units between these three loci.
(b) What is the coefficient of coincidence?
Answer:
(a) Lobe is in the middle.
smooth abdomen——5——Lobe———————15————————straw body
(b) zero
Section: 5.5
15) In Drosophila, assume that the gene for scute bristles (s) is located at map position 0.0 and that the gene for ruby eyes (r) is at position 15.0. Both genes are located on the X chromosome and are recessive to their wild-type alleles. A cross is made between scute-bristled females and ruby-eyed males. Phenotypically wild F1 females were then mated to homozygous double mutant males, and 1000 offspring were produced. Give the phenotypes and frequencies expected.
Answer: scute = 425; ruby = 425; wild type = 75; scute-ruby = 75
Section: 5.5
16) Assume that a cross is made between AaBb and aabb plants and that the offspring occur in the following numbers: 106 AaBb, 48 Aabb, 52 aaBb, 94 aabb. These results are consistent with which arrangement of genes?
Answer: In the AaBb parent, the dominant alleles are on one homolog, and the recessive alleles are on the other.
Section: 5.2
17) In the fruit fly, Drosophila melanogaster, a spineless (no wing bristles) female fly is mated to a male that is claret (dark eyes) and hairless (no thoracic bristles). Phenotypically wild-type F1 female progeny were mated to fully homozygous (mutant) males, and the following progeny (1000 total) were observed:
Phenotypes Number Observed
spineless 321
wild 38
claret, spineless 130
claret 18
claret, hairless 309
hairless, claret, spineless 32
hairless 140
hairless, spineless 12
(a) Which gene is in the middle?
(b) With respect to the three genes mentioned in the problem, what are the genotypes of the homozygous parents used in making the phenotypically wild F1 heterozygote?
(c) What are the map distances between the three genes? A correct formula with the values “plugged in” for each distance will be sufficient.
(d) What is the coefficient of coincidence? A correct formula with the values “plugged in” will be sufficient.
Answer:
(a) hairless
(b) cl h + /cl h + and + + sp/ + + sp
(c) cl————30————h——10——sp
(d) 0.03/0.03 = 1
Section: 5.3, 5.5
18) Three loci, mitochondrial malate dehydrogenase that forms a and b (MDHa, MDHb), glucouronidase that forms 1 and 2 (GUS1, GUS2), and a histone gene that forms + and – (H+, H-), are located on chromosome #7 in humans. Assume that the MDH locus is at position 35, GUS at position 45, and H at position 75. A female whose mother was homozygous for MDHa, GUS2, and H+ and whose father was homozygous for MDHb, GUS1, and H- produces a sample of 1000 egg cells. Give the genotypes and expected numbers of the various types of cells she would produce. Assume no chromosomal interference.
Answer:
MDHa GUS2 H+ = 315 MDHa GUS2 H– = 135
MDHb GUS1 H– = 315 MDHb GUS1 H+ = 135
MDHa GUS1 H– = 35 MDHa GUS1 H+ = 15
MDHb GUS2 H+ = 35 MDHb GUS2 H– = 15
Section: 5.3
19) To which scientific activities do the terms synkaryon and heterokaryon refer?
Answer: cell (heterokaryon) and nuclear (synkaryon) fusion and gene mapping in eukaryotes
Section: 5.6
20) (a) In a three-point mapping experiment, which three general classes of offspring are expected (assuming crossovers occur)?
(b) How many genotypic classes are expected?
Answer:
(a) noncrossovers, single crossovers, double crossovers
(b) 8
Section: 5.3
21) What is the expected evolutionary significance of genetic recombination?
Answer: production of genetic variation
Section: 5.1
22) Assume that two genes are 80 map units apart on chromosome #2 of Drosophila and that a cross is made between a doubly heterozygous female and a homozygous recessive male. What percent recombination would be expected in the offspring of this type of cross?
Answer: 50% (maximum)
Section: 5.4
23) Provide a brief definition for positive interference.
Answer: A crossover in one region decreases the likelihood of crossovers in nearby regions.
Section: 5.4
24) Two lines of work indicated that crossing over actually involves breakage and reunion of chromatid material. Which organisms were involved, and who did the work?
Answer: Creighton and McClintock (corn) and Stern (Drosophila)
Section: 5.8
25) What advantage does BrdU (bromodeoxyuridine) have in the study of chromosome structure and recombination?
Answer: Chromatids stained with BrdU in both DNA strands are distinguishable from those with BrdU in only one strand of the double helix.
Section: 5.9
26) Sister chromatid exchanges increase in frequency in the presence of X-rays, certain viruses, ultraviolet light, and certain chemical mutagens. In which autosomal recessive disorder is there an increase in sister chromatid exchanges?
Answer: Bloom syndrome
Section: 5.9
27) Under what circumstance might two loci be on the same chromosome but behave as if they were independently assorting in crosses?
Answer: If the genes are far apart, they may show independent assortment.
Section: 5.2
28) In the early 1900s, two scientists noted that there were many more genes than chromosome pairs, thus setting the stage for the suggestion that some gene loci might be linked during meiotic processes. Who were these two scientists?
Answer: Walter Sutton and Theodor Boveri
Section: Introduction
29) What is the relationship between the degree of crossing over and the distance between two genes?
Answer: It is direct; as the distance increases, the frequency of recombination increases.
Section: 5.2
30) At what stage of the meiotic cell cycle and during what chromosomal configuration does crossing over occur?
Answer: at the four-strand stage of meiosis, after synapsis of homologous chromosomes, and before the end of prophase I
Section: 5.2
31) What is meant by the term second-division segregation?
Answer: a condition that gives evidence of a crossover between a gene in question and the centromere: aa++aa++ or aa++++aa, for example
Section: 5.10
32) Describe a convenient method for determining gene order from three-point cross results.
Answer: Compare the double-crossover class with the parental class and ask which gene has switched places. The gene that switched places is in the middle.
Section: 5.3
33) Assume that a cross is made between an albino (a) strain of Neurospora and one that is normally pigmented (A). The frequency with which second-division segregation occurs indicates that there are 25 map units between the a locus and the centromere. Given the four asci below, shade in the ascospore patterns with the appropriate frequency that would provide such a map distance (25 map units).
Answer:
Section: 5.10
34) Describe the general relationship between gene location and crossover frequency between those genes.
Answer: In general, the more distant the two genes are, the higher is the frequency of crossing over between them.
Section: 5.2
35) Why is it possible to “map” the centromere in Neurospora and not in most other organisms?
Answer: Ascospores are held in order as meiotic products. This order is dependent on centromere migration, and a comparison of ascospore patterns allows one to determine whether crossovers have occurred. Quantifying such crossovers allows one to estimate map distance between the gene in question and the centromere.
Section: 5.10
36) Which yields more genetic variation, meiotic or mitotic crossing over?
Answer: Meiotic crossing over leads to significant genetic variation.
Section: Introduction, 5.1
37) When considering linked genes, which category of ascospore arrangement occurs most frequently: parental ditype, nonparental ditype, or tetratype?
Answer: parental ditype
Section: 5.10
38) If two genes assort independently, which categories of ascospore arrangements occur in approximately equal frequencies: parental ditype, nonparental ditype, or tetratype?
Answer: parental ditype and nonparental ditype
Section: 5.10
39) Mendel predicted that some genes would be carried in the same chromosome.
Answer: FALSE
Section: 5.11
40) The cross GE/ge × ge/ge produces the following progeny: GE/ge 404, ge/ge 396, gE/ge 97, Ge/ge 103. From these data, one can conclude that the G and E loci assort independently.
Answer: FALSE
Section: 5.2
41) The cross GE/ge × ge/ge produces the following progeny: GE/ge 404, ge/ge 396, gE/ge 97, Ge/ge 103. From these data, one can conclude that the recombinant progeny are gE/ge and Ge/ge.
Answer: TRUE
Section: 5.2
42) The cross GE/ge × ge/ge produces the following progeny: GE/ge 404, ge/ge 396, gE/ge 97, Ge/ge 103. From these data, one can conclude that there are 20 map units between the G and E loci.
Answer: TRUE
Section: 5.2
43) Linkage (viewed from results of typical crosses) always occurs when two loci are on the same chromosome.
Answer: FALSE
Section: 5.2
44) Positive interference occurs when a crossover in one region of a chromosome interferes with crossovers in nearby regions.
Answer: TRUE
Section: 5.4
45) If the frequency of parental ditypes is greater than the frequency of nonparental ditypes, then the genes in question are linked.
Answer: TRUE
Section: 5.10
46) In Drosophila, the frequency of crossing over in males is about equal to the frequency of crossing over in females.
Answer: FALSE
Section: 5.5
47) If two gene loci are on nonhomologous chromosomes, genes at these loci are expected to assort independently.
Answer: TRUE
Section: 5.1
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Original price was: $30.00.$20.00Current price is: $20.00.
Original price was: $30.00.$20.00Current price is: $20.00.
Original price was: $30.00.$20.00Current price is: $20.00.
Original price was: $30.00.$20.00Current price is: $20.00.
Original price was: $30.00.$20.00Current price is: $20.00.
