Question 1

The chromosome in the previous question is now said to be

Accepted Answer

A)  polymorphic. 
B)  autosomal. 
C)  recombinant. 
D)  homologous. 
E)  aneuploid. 
A)  polymorphic. 
B)  autosomal. 
C)  recombinant. 
D)  homologous. 
E)  aneuploid.

Question 2

If two genes are not linked, then the expected phenotypic ratio resulting from a testcross is

Accepted Answer

A)  1:2:1. 
B)  1:1. 
C)  1:1:1:1. 
D)  3:1. 
E)  9:3:3:1. 
A)  1:2:1. 
B)  1:1. 
C)  1:1:1:1. 
D)  3:1. 
E)  9:3:3:1.

Question 3

Two genes that are located far from each other on the same chromosome will show a higher frequency of recombination than two genes that are close together on the chromosome.

Accepted Answer

A) True 
 B)False

Question 4

A chromosomal arrangement in which each homolog carries the wild-type allele of one gene and the mutant allele of the other gene is called coupling.

Accepted Answer

A) True 
 B)False

Question 5

Genes may show 50 percent recombination either when the genes are on different chromosomes or when the genes are far apart on the same chromosome.

Accepted Answer

A) True 
 B)False

Question 6

The accuracy of map distances based on recombination frequencies

Accepted Answer

A)  decreases as the chance of multiple crossovers increases. 
B)  is greatest when genes are at a distance of 7 mu or less. 
C)  decreases as the distance between genes increases. 
D)  increases as the distance between genes increases. 
E)  All but D. 
A)  decreases as the chance of multiple crossovers increases. 
B)  is greatest when genes are at a distance of 7 mu or less. 
C)  decreases as the distance between genes increases. 
D)  increases as the distance between genes increases. 
E)  All but D.

Question 7

When does crossing over occur?

Accepted Answer

A)  Anytime during the second meiotic division 
B)  Anytime at random during division 
C)  Prophase II of meiosis 
D)  Prophase I of meiosis 
E)  Interphase prior to meiosis 
A)  Anytime during the second meiotic division 
B)  Anytime at random during division 
C)  Prophase II of meiosis 
D)  Prophase I of meiosis 
E)  Interphase prior to meiosis

Question 8

Crossing over is

Accepted Answer

A)  the place on a homologous pair of chromosomes at which a physical exchange occurs. 
B)  the reciprocal exchange of homologous regions of chromatids. 
C)  an event that only takes place during meiosis. 
D)  not useful in mapping genes. 
E)  an extremely rare event. 
A)  the place on a homologous pair of chromosomes at which a physical exchange occurs. 
B)  the reciprocal exchange of homologous regions of chromatids. 
C)  an event that only takes place during meiosis. 
D)  not useful in mapping genes. 
E)  an extremely rare event.

Question 9

A chromosome contains alleles for blue eyes and blond hair. After meiosis the same chromosome contains alleles for blue eyes and brown hair. This occurred because of

Accepted Answer

A)  crossing over. 
B)  interference. 
C)  independent assortment. 
D)  segregation. 
E)  nondisjunction. 
A)  crossing over. 
B)  interference. 
C)  independent assortment. 
D)  segregation. 
E)  nondisjunction.

Question 10

The map distance between the two outside genes in a linkage group of three genes can be calculated by adding the map distances between the two adjacent pairs of the three genes.

Accepted Answer

A) True 
 B)False

Question 11

One genetic map unit is equal to a recombination frequency of

Accepted Answer

A)  10 percent. 
B)  1 percent. 
C)  100 percent. 
D)  50 percent. 
E)  5 percent. 
A)  10 percent. 
B)  1 percent. 
C)  100 percent. 
D)  50 percent. 
E)  5 percent.

Question 12

The cross represented by a+b+c+/abc × abc/abc is a

Accepted Answer

A)  two-point testcross. 
B)  parental cross. 
C)  three-point testcross. 
D)  haploid cross. 
E)  None of the above 
A)  two-point testcross. 
B)  parental cross. 
C)  three-point testcross. 
D)  haploid cross. 
E)  None of the above

Question 13

T. H. Morgan and his group found that among the offspring of genetic crosses, parental phenotypic classes were the most frequent, while recombinant classes occurred less frequently. This observation led Morgan to conclude that

Accepted Answer

A)  genes on different chromosomes do not assort independently. 
B)  alleles of linked genes assort independently. 
C)  genes on different chromosomes assort independently. 
D)  all genes are linked. 
E)  alleles of some genes assort together. 
A)  genes on different chromosomes do not assort independently. 
B)  alleles of linked genes assort independently. 
C)  genes on different chromosomes assort independently. 
D)  all genes are linked. 
E)  alleles of some genes assort together.

Question 14

Genes that are located on the same chromosome are

Accepted Answer

A)  linked. 
B)  chromologs. 
C)  homologous. 
D)  homozygous. 
E)  coupled. 
A)  linked. 
B)  chromologs. 
C)  homologous. 
D)  homozygous. 
E)  coupled.

Question 15

Of the three pairs of genes above, which ones are closest to each other and which ones are farthest apart?

Accepted Answer

X and Z are closest, being 11.

Question 16

Why can a male fruit fly be used as a testcross individual with a female heterozygote to test for recombinant phenotypes in X-linked genes?

Accepted Answer

Since the male only has one X

Question 17

A triple-point testcross of a plant is used to determine the order of linked genes g, t, and l. The wild-type parental phenotypes are green, tall, and leafy, represented by the triple heterozygote g+t+l+/gtl. The mutant plants are red, dwarf, and sparse, represented by the triple recessive genotype gtl/gtl. The least frequent phenotypes in the progeny of the testcross are red, tall, and leafy, and green, dwarf, and sparse. What is the order of the three genes?

Accepted Answer

The least frequent phenotypes represent

Question 18

A coefficient of coincidence of zero is the same as an interference value of zero.

Accepted Answer

A) True 
 B)False

Question 19

For a two-point testcross, if the percentage of recombinants is 50 percent, the two genes may be

Accepted Answer

A)  on different chromosomes. 
B)  not linked. 
C)  distant from each other on the same chromosome. 
D)  both A and B. 
E)  all of the above. 
A)  on different chromosomes. 
B)  not linked. 
C)  distant from each other on the same chromosome. 
D)  both A and B. 
E)  all of the above.

Question 20

How could you determine whether two genes, A and C, showing 50 percent recombination in genetic crosses, are on different chromosomes or far apart on the same chromosome?

Accepted Answer

If another gene, E, shows less

Exam 6: Extensions of Mendelian Genetic Principles

The chromosome in the previous question is now said to be

If two genes are not linked, then the expected phenotypic ratio resulting from a testcross is

Two genes that are located far from each other on the same chromosome will show a higher frequency of recombination than two genes that are close together on the chromosome.

A chromosomal arrangement in which each homolog carries the wild-type allele of one gene and the mutant allele of the other gene is called coupling.

Genes may show 50 percent recombination either when the genes are on different chromosomes or when the genes are far apart on the same chromosome.

The accuracy of map distances based on recombination frequencies

When does crossing over occur?

Crossing over is

A chromosome contains alleles for blue eyes and blond hair. After meiosis the same chromosome contains alleles for blue eyes and brown hair. This occurred because of

The map distance between the two outside genes in a linkage group of three genes can be calculated by adding the map distances between the two adjacent pairs of the three genes.

One genetic map unit is equal to a recombination frequency of

The cross represented by a+b+c+/abc × abc/abc is a

T. H. Morgan and his group found that among the offspring of genetic crosses, parental phenotypic classes were the most frequent, while recombinant classes occurred less frequently. This observation led Morgan to conclude that

Genes that are located on the same chromosome are

Of the three pairs of genes above, which ones are closest to each other and which ones are farthest apart?

Why can a male fruit fly be used as a testcross individual with a female heterozygote to test for recombinant phenotypes in X-linked genes?

A coefficient of coincidence of zero is the same as an interference value of zero.

For a two-point testcross, if the percentage of recombinants is 50 percent, the two genes may be

How could you determine whether two genes, A and C, showing 50 percent recombination in genetic crosses, are on different chromosomes or far apart on the same chromosome?

Genetics of Bacteria and Bacteriophages

Variations in Chromosome Structure and Number

Advanced Gene Mapping in Eukaryotes

Gene Mapping in Eukaryotes

Quantitative Genetics

Chromosomal Basis of Inheritance

Molecular Evolution

Population Genetics

Non-Mendelian Inheritance

Genetics of Cancer

Genetic Analysis of Development

Regulation of Gene Expression in Eukaryotes

Mendelian Genetics

Regulation of Gene Expression in Bacteria and Bacteriophages

Genomics

Applications of Recombinant DNA Technology

Recombinant DNA Technology

DNA Mutation, DNA Repair, and Transposable Elements

Gene Expression: Translation

Gene Expression: Transcription

Gene Control of Proteins

DNA Replication

DNA: The Genetic Material

Genetics: an Introduction

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