Question 1

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 female 
A) masculine characteristics such as facial hair 
B) enlarged genital structures 
C) excessive emotional instability 
D) normal female 
E) sterile female D

Question 2

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. 
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. B

Question 3

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. 
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. D

Question 4

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 aneuploidy 
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 aneuploidy

Question 5

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 metaphase 
A) early prophase 
B) late telophase 
C) anaphase 
D) late anaphase or early telophase 
E) late prophase or metaphase

Question 6

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. 
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.

Question 7

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. 
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.

Question 8

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. 
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.

Question 9

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

Question 10

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 genes 
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 genes

Question 11

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. 
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.

Question 12

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

Question 13

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

Question 14

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. 
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.

Question 15

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. 
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.

Question 16

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. 
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.

Question 17

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) duplication 
A) deletion 
B) transversion 
C) inversion 
D) translocation 
E) duplication

Question 18

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. 
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.

Question 19

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. 
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.

Question 20

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. 
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.

Exam 15: The Chromosomal Basis of Inheritance

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

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

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

What is a syndrome?

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

Why does recombination between linked genes continue to occur?

-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

Which of the following produces a Mendelian pattern of inheritance?

What is the reason that linked genes are inherited together?

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?

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?

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

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

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

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

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?

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

Introduction: Evolution and Themes of Biology

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

Cell Communication

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Molecular Basis of Inheritance

From Gene to Protein

Regulation of Gene Expression

Viruses

Dna Tools and Biotechnology

Genomes and Their Evolution

Descent With Modification: a Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity Ii: the Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signalling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behaviour

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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