Question 1

Sturtevant provided genetic evidence for the existence of four pairs of chromosomes in Drosophila in which of these ways?

Accepted Answer

A)  There are four major functional classes of genes in Drosophila.
B)  Drosophila genes cluster into four distinct groups of linked genes.
C)  The overall number of genes in Drosophila is a multiple of four.
D)  The entire Drosophila genome has approximately 400 map units.
E)  Drosophila genes have, on average, four different alleles.F) A) and B)
G) A) and C) B

Question 2

Why does recombination between linked genes continue to occur?

Accepted Answer

A)  Recombination is a requirement for independent assortment.
B)  Recombination must occur or genes will not assort independently.
C)  New allele combinations are acted upon by natural selection.
D)  The forces on the cell during meiosis II always result in recombination.
E)  Without recombination there would be an insufficient number of gametes.F) B) and D)
G) C) and E)

Question 3

Genomic imprinting is generally due to the addition of methyl (-CH₃) groups to ?C nucleotides in order to silence a given gene. If this depends on the sex of the parent who transmits the gene, which of the following must be true?

Accepted Answer

A)  Methylation of C is permanent in a gene.
B)  Genes required for early development stages must not be imprinted.
C)  Methylation of this kind must occur more in males than in females.
D)  Methylation must be reversible in ovarian and testicular cells.
E)  The imprints are transmitted only to gamete-producing cells.F) A) and E)
G) B) and E)

Question 4

Use the following information to answer the questions below.
The following is a map of four genes on a chromosome.
 
-Which two genes would you likely find inherited together?

Accepted Answer

A)  A and W
B)  W and E
C)  E and G
D)  A and E
E)  A and GF) C) and D)
G) A) and D)

Question 5

Which of the following produces a Mendelian pattern of inheritance?

Accepted Answer

A)  genomic imprinting
B)  a mitochondrial gene mutation
C)  a chloroplast gene mutation
D)  viral genomes that inhabit egg cytoplasm
E)  a trait acted upon by many genesF) A) and E)
G) A) and D)

Question 6

What is a syndrome?

Accepted Answer

A)  a characteristic facial appearance
B)  a group of traits, all of which must be present if an aneuploidy is to be diagnosed
C)  a group of traits typically found in conjunction with a particular chromosomal aberration or gene mutation
D)  a characteristic trait usually given the discoverer's name
E)  a characteristic that only appears in conjunction with one specific aneuploidyF) B) and D)
G) A) and E)

Question 7

In 1956, Tijo and Levan first successfully counted human chromosomes. What is the reason it took so many years to do so?

Accepted Answer

A)  Watson and Crick's structure of DNA was not done until 1953.
B)  Chromosomes were piled up on top of one another in the nucleus.
C)  Chromosomes were not distinguishable during interphase.
D)  A method had not yet been devised to halt mitosis at metaphase.
E)  Chromosomes were piled up on top of one another in the nucleus, chromosomes were not distinguishable during interphase, and a method had not yet been devised to halt mitosis at metaphase.F) None of the above
G) A) and B)

Question 8

In cats, black fur colour is caused by an X-linked allele; the other allele at this locus causes orange colour. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?

Accepted Answer

A)  tortoiseshell females; tortoiseshell males
B)  black females; orange males
C)  orange females; orange males
D)  tortoiseshell females; black males
E)  orange females; black malesF) A) and D)
G) B) and C)

Question 9

What is the reason that linked genes are inherited together?

Accepted Answer

A)  They are located close together on the same chromosome.
B)  The number of genes in a cell is greater than the number of chromosomes.
C)  Chromosomes are unbreakable.
D)  Alleles are paired together during meiosis.
E)  Genes align that way during metaphase I of meiosis.F) A) and B)
G) A) and C)

Question 10

At which phase(s) is it preferable to obtain chromosomes to prepare a karyotype?

Accepted Answer

A)  early prophase
B)  late telophase
C)  anaphase
D)  late anaphase or early telophase
E)  late prophase or metaphaseF) D) and E)
G) A) and B)

Question 11

Map units on a linkage map cannot be relied upon to calculate physical distances on a chromosome for which of the following reasons?

Accepted Answer

A)  The frequency of crossing over varies along the length of the chromosome.
B)  The relationship between recombination frequency and map units is different in every individual.
C)  Physical distances between genes change during the course of the cell cycle.
D)  The gene order on the chromosomes is slightly different in every individual.
E)  Linkage map distances are identical between males and females.F) A) and B)
G) C) and D)

Question 12

The greatest distance among the three genes is between a and c. What does this mean?

Accepted Answer

A)  Gene a is closest to b.
B)  Genes are in the order: a-b-c.
C)  Gene a is not recombining with c.
D)  Gene a is between b and c.
E)  Distance a-b is equal to distance a-c.F) C) and D)
G) B) and C) D

Question 13

Three genes at three loci are being mapped in a particular species. Each has two phenotypes, one of which is markedly different from the wild type. The unusual allele of the first gene is inherited with either of the others about 50% of the time. However, the unusual alleles of the other two genes are inherited together 14.4% of the time. Which of the following describes what is happening?

Accepted Answer

A)  The genes are showing independent assortment.
B)  The three genes are linked.
C)  The first gene is linked but the other two are not.
D)  The first gene is assorting independently from the other two that are linked.
E)  The first gene is located 14.4 units apart from the other two.F) None of the above
G) C) and D)

Question 14

One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called?

Accepted Answer

A)  deletion
B)  transversion
C)  inversion
D)  translocation
E)  duplicationF) D) and E)
G) A) and B)

Question 15

Chimpanzees, gorillas, and orangutans have DNA sequences that are almost identical to those of humans; however, these genes are found on 24 pairs of chromosomes in apes, while humans have 23 pairs. The C2 chromosome in humans is a large chromosome with similar banding pattern and DNA sequences to two smaller chromosomes in apes (C2 and C4) . In addition it appears to have both a vestigial second centromere and telomere sequences in the middle of the strand.
-What could explain these observations?

Accepted Answer

A)  The human ancestor originally had 24 pairs but complete fusion of C2 and C4 occurred, reducing the total number of chromosomes.
B)  A nondisjunction event must have occurred in the human ancestor, increasing the overall ploidy.
C)  The loss of a chromosome is due to a deletion event in the human ancestor.
D)  C2 must have undergone an inversion with C4.
E)  There is not enough information to speculate.F) All of the above
G) A) and D)

Question 16

A woman is found to have 47 chromosomes, including three X chromosomes. Which of the following describes her expected phenotype?

Accepted Answer

A)  masculine characteristics such as facial hair
B)  enlarged genital structures
C)  excessive emotional instability
D)  normal female
E)  sterile femaleF) B) and E)
G) All of the above D

Question 17

If nondisjunction occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis?

Accepted Answer

A)  All the gametes will be diploid.
B)  Half of the gametes will be n + 1, and half will be n - 1.
C)  1/4 of the gametes will be n + 1, 1/4 will be n - 1, and 1/2 will be n.
D)  There will be three extra gametes.
E)  Two of the four gametes will be haploid, and two will be diploid.F) B) and D)
G) A) and E)

Question 18

Chimpanzees, gorillas, and orangutans have DNA sequences that are almost identical to those of humans; however, these genes are found on 24 pairs of chromosomes in apes, while humans have 23 pairs. The C2 chromosome in humans is a large chromosome with similar banding pattern and DNA sequences to two smaller chromosomes in apes (C2 and C4) . In addition it appears to have both a vestigial second centromere and telomere sequences in the middle of the strand.
-It is believed that early hominins interbred with each other. Ancient humans may have successfully mated with both Neanderthal and Denisovans. What must be true of these species for this to occur? They must have

Accepted Answer

A)  been triploid.
B)  had a similar C2 to humans and only 23 pairs of chromosomes.
C)  actually been human.
D)  had 24 chromosomes, so nondisjunction could occur.
E)  had wild type phenotypic traits identical to humans.F) C) and D)
G) D) and E)

Question 19

Leber's hereditary optic neuropathy does not follow Mendelian genetic because it is

Accepted Answer

A)  the result of genomic imprinting.
B)  a mutation in the mitochondrial genome.
C)  a mutation in the plastid genome.
D)  X-linked.
E)  Y-linked.F) A) and C)
G) C) and D)

Question 20

-The pedigree in the figure above shows the transmission of a trait in a particular family. Based on this pattern of transmission, the trait is most likely

Accepted Answer

A)  mitochondrial.
B)  autosomal recessive.
C)  sex-linked dominant.
D)  sex-linked recessive.
E)  autosomal dominant.F) B) and D)
G) A) and E)

Exam 15: The Chromosomal Basis of Inheritance

Sturtevant provided genetic evidence for the existence of four pairs of chromosomes in Drosophila in which of these ways?

Correct Answer
verified
B

Why does recombination between linked genes continue to occur?

Correct Answer
verified

Genomic imprinting is generally due to the addition of methyl (-CH₃) groups to ?C nucleotides in order to silence a given gene. If this depends on the sex of the parent who transmits the gene, which of the following must be true?

Correct Answer
verified

Use the following information to answer the questions below. The following is a map of four genes on a chromosome. -Which two genes would you likely find inherited together?

Correct Answer
verified

Which of the following produces a Mendelian pattern of inheritance?

Correct Answer
verified

What is a syndrome?

Correct Answer
verified

In 1956, Tijo and Levan first successfully counted human chromosomes. What is the reason it took so many years to do so?

Correct Answer
verified

In cats, black fur colour is caused by an X-linked allele; the other allele at this locus causes orange colour. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?

Correct Answer
verified

What is the reason that linked genes are inherited together?

Correct Answer
verified

At which phase(s) is it preferable to obtain chromosomes to prepare a karyotype?

Correct Answer
verified

Map units on a linkage map cannot be relied upon to calculate physical distances on a chromosome for which of the following reasons?

Correct Answer
verified

The greatest distance among the three genes is between a and c. What does this mean?

Correct Answer
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D

Correct Answer
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One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called?

Correct Answer
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Correct Answer
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A woman is found to have 47 chromosomes, including three X chromosomes. Which of the following describes her expected phenotype?

Correct Answer
verified
D

If nondisjunction occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis?

Correct Answer
verified

Correct Answer
verified

Leber's hereditary optic neuropathy does not follow Mendelian genetic because it is

Correct Answer
verified

-The pedigree in the figure above shows the transmission of a trait in a particular family. Based on this pattern of transmission, the trait is most likely

Correct Answer
verified

Exam 15: The Chromosomal Basis of Inheritance

Sturtevant provided genetic evidence for the existence of four pairs of chromosomes in Drosophila in which of these ways?

Correct AnswerverifiedB

Why does recombination between linked genes continue to occur?

Correct AnswerverifiedShow Answer

Genomic imprinting is generally due to the addition of methyl (-CH₃) groups to ?C nucleotides in order to silence a given gene. If this depends on the sex of the parent who transmits the gene, which of the following must be true?

Correct AnswerverifiedShow Answer

Use the following information to answer the questions below. The following is a map of four genes on a chromosome. -Which two genes would you likely find inherited together?

Correct AnswerverifiedShow Answer

Which of the following produces a Mendelian pattern of inheritance?

Correct AnswerverifiedShow Answer

What is a syndrome?

Correct AnswerverifiedShow Answer

In 1956, Tijo and Levan first successfully counted human chromosomes. What is the reason it took so many years to do so?

Correct AnswerverifiedShow Answer

In cats, black fur colour is caused by an X-linked allele; the other allele at this locus causes orange colour. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?

Correct AnswerverifiedShow Answer

What is the reason that linked genes are inherited together?

Correct AnswerverifiedShow Answer

At which phase(s) is it preferable to obtain chromosomes to prepare a karyotype?

Correct AnswerverifiedShow Answer

Map units on a linkage map cannot be relied upon to calculate physical distances on a chromosome for which of the following reasons?

Correct AnswerverifiedShow Answer

The greatest distance among the three genes is between a and c. What does this mean?

Correct AnswerverifiedD

Correct AnswerverifiedShow Answer

One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A woman is found to have 47 chromosomes, including three X chromosomes. Which of the following describes her expected phenotype?

Correct AnswerverifiedD

If nondisjunction occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Leber's hereditary optic neuropathy does not follow Mendelian genetic because it is

Correct AnswerverifiedShow Answer

-The pedigree in the figure above shows the transmission of a trait in a particular family. Based on this pattern of transmission, the trait is most likely

Correct AnswerverifiedShow Answer

Correct Answer
verified
B

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D

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D

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