Question 1

Gene duplications may be caused by
A) the crossing over of misaligned chromosomes.
B) deletion of important genetic information.
C) reciprocal translocations.
D) position effect.
E) None of the answers are correct

Accepted Answer

Gene duplications can occur through an error in meiosis where homologous chromosomes misalign and cross over with non-sister chromatids, resulting in unequal crossovers and the duplication of genetic material.

Question 2

Given the following sequence of genes on a chromosome, determine what change in chromosome structure occurred. (the * indicates the centromere) before A B C D * E F G H
After A B C D * E F E F G H
A) Terminal deficiency
B) Interstitial deficiency
C) Inversion
D) Gene duplication

Accepted Answer

Gene duplication occurs when a segment of a chromosome is duplicated and both copies end up in the same chromosome. In this case, the genes E and F are repeated in sequence, indicating a duplication of these genes.

Question 3

An inversion heterozygote contains
A) two homologous chromosomes with inversions.
B) two normal chromosomes.
C) one normal chromosome and one chromosome with an inversion.
D) None of the answers are correct

Accepted Answer

An inversion heterozygote has one normal chromosome and one chromosome with an inversion. Therefore, option C is the correct answer.

Question 4

Inversion loops can occur in
A) paracentric inversions.
B) pericentric inversions.
C) gene duplications.
D) reciprocal translocations.
E) both paracentric inversions and pericentric inversions.

Accepted Answer

Inversion loops can occur in both paracentric inversions and pericentric inversions. Inversion loops are formed during meiosis when homologous chromosomes with different structural variations (inversions, translocations) align in a way that creates a loop structure. Inversion loops are often associated with crossover events that can result in chromosomal abnormalities in the offspring.

Question 5

Given the following sequence of genes on a chromosome, determine what change in chromosome structure occurred. (the * indicates the centromere) before A B C D * E F G H
After A C D * E F G H
A) Terminal deletion
B) Interstitial deletion
C) Inversion
D) Gene duplication

Accepted Answer

Interstitial deletion is the correct answer because gene B is missing from the sequence without affecting the terminal parts of the chromosome, indicating a segment from the middle (interstitial part) has been deleted.

Question 6

A loss of an internal piece of a chromosome is called a ________.
A) reciprocal translocation
B) terminal deficiency
C) interstitial deletion
D) gene duplication

Accepted Answer

A loss of an internal piece of a chromosome is called an interstitial deletion. Reciprocal translocation involves exchange of pieces between non-homologous chromosomes, terminal deficiency involves loss of a segment at the end of a chromosome, and gene duplication involves a segment of a chromosome being duplicated.

Question 7

Which algebraic expression would be used to denote a trisomic organism?
A) 3n
B) 2n − 1
C) 2n + 1
D) 2n + 2

Accepted Answer

A trisomic organism has one extra copy of a chromosome. In terms of the number of sets of chromosomes (n), a normal organism has 2n, while a trisomic organism has 2n+1 chromosomes. Therefore, the expression that denotes a trisomic organism is 2n+1.

Question 8

Which type of chromosome has the longest p arm of the chromosome?
A) Acrocentric
B) Metacentric
C) Telocentric
D) Submetacentric

Accepted Answer

Metacentric chromosomes have centromeres that are approximately in the middle, making their p (short) and q (long) arms almost equal in length. This configuration can sometimes make the p arm appear relatively long compared to chromosomes where the centromere is significantly off-center.

Question 9

Robertsonian translocations usually occur between what types of chromosomes?
A) Metacentric
B) Acrocentric
C) Telocentric
D) Submetacentric

Accepted Answer

Robertsonian translocations usually occur between acrocentric chromosomes, which have a short arm that is almost non-existent and a long arm that is much longer. This makes it easier for the chromosomes to break and rejoin with each other.

Question 10

Human genetic diseases such a Cri-du-chat, Angelman syndrome and Prader-Willi syndrome are the result of which type of chromosomal change?
A) Translocations
B) Duplications
C) Deletions
D) Inversions

Accepted Answer

Cri-du-chat, Angelman syndrome, and Prader-Willi syndrome are caused by deletions of specific regions on chromosomes. Cri-du-chat is due to a deletion on chromosome 5, while Angelman and Prader-Willi syndromes result from deletions on chromosome 15.

Question 11

Familial Down syndrome is a result of
A) inversion.
B) deficiency.
C) gene duplication.
D) translocation.

Accepted Answer

Familial Down syndrome is caused by a Robertsonian translocation, where part of chromosome 21 is translocated onto another chromosome, typically chromosome 14. This results in the usual genetic makeup for Down syndrome (three copies of chromosome 21), but in a way that can be inherited through families.

Question 12

Edward and Patau syndromes are examples of ________.
A) aneuploidy
B) allopolyploidy
C) autopolyploidy
D) translocations

Accepted Answer

Edward and Patau syndromes are examples of aneuploidy, which is a condition where there is an abnormal number of chromosomes in the cell. In Edward syndrome, there is an extra copy of chromosome 18, while in Patau syndrome, there is an extra copy of chromosome 13.

Question 13

Inversions are contained within what percent of the human population?
A) Less than 1%
B) Approximately 2%
C) Approximately 5%
D) Greater than 10%

Accepted Answer

Research suggests that inversions are present in approximately 2% of the human population.

Question 14

Which of the following is not an example of euploidy?
A) Tetraploid
B) Polyploid
C) Triploid
D) Diploid
E) Aneuploid

Accepted Answer

Euploidy refers to the condition of having a complete set(s) of chromosomes (e.g. diploid with two complete sets). Aneuploidy, on the other hand, is a condition of having an abnormal number of chromosomes (e.g. trisomy 21 with three copies of chromosome 21). Therefore, aneuploidy is not an example of euploidy.

Question 15

Which chromosomal change rarely has an effect on the phenotype of the individual who carries it?
A) Robertsonian translocation
B) Unbalanced translocation
C) Balanced translocation
D) Chromosome loss

Accepted Answer

A balanced translocation occurs when a piece of one chromosome is exchanged with a piece of another chromosome but with no change in the total amount of genetic material. As a result, the phenotype of the individual carrying the balanced translocation is not usually affected because they have the correct amount of genetic material.

Question 16

The production of gene families, such as the globin genes is the result of ________.
A) inversions
B) deficiencies
C) gene duplications
D) simple translocations
E) None of the answers are correct

Accepted Answer

Gene duplications lead to the creation of multiple copies of a gene, which can then diverge over time through mutations and accumulate differences. This process can eventually result in the formation of a gene family, such as the globin genes, which are involved in oxygen transport in vertebrate blood. Inversions, deficiencies, and translocations can also give rise to genetic variation, but they are not directly responsible for the production of gene families.

Question 17

Given the following sequence of genes on a chromosome, determine what change in chromosome structure occurred. (the * indicates the centromere) before A B C D * E F G H
After A B G F E * D C H
A) Reciprocal translocation
B) Pericentric inversion
C) Paracentric inversion
D) Gene duplication
E) None of the answers are correct

Accepted Answer

The sequence change from "A B C D * E F G H" to "A B G F E * D C H" indicates a pericentric inversion, as the order of genes is reversed across the centromere (from E F G to G F E and from C D to D C).

Question 18

The effects of a deficiency on an organism is dependent on the size of the deletion and the importance of the missing genetic material to the organism.

Accepted Answer

The statement is true as the severity of the effects of a genetic deletion can vary depending on the size and importance of the missing genetic material to the organism.

Question 19

Klinefelter and Turner syndromes are examples of
A) sex chromosome aneuploidy.
B) autosomal aneuploidy.
C) reciprocal translocations.
D) paracentric inversions.

Accepted Answer

Klinefelter and Turner syndromes are caused by variations in the number of sex chromosomes, specifically aneuploidy of the X or Y chromosome. Autosomal aneuploidy involves variations in the number of chromosomes that are not sex chromosomes, while reciprocal translocations and paracentric inversions involve structural changes in chromosomes rather than variations in chromosome number.

Question 20

A translocation cross may occur in an individual that has a(n)
A) reciprocal translocation.
B) unbalanced translocation.
C) simple translocation.
D) All of the answers are correct

Accepted Answer

A translocation cross can only occur in an individual with a reciprocal translocation, which involves the exchange of genetic material between two chromosomes. Unbalanced translocations involve a loss or gain of genetic material and simple translocations involve the transfer of a single segment of genetic material.

Quiz 8: Variation in Chromosome Structure and Number

Gene duplications may be caused by

Given the following sequence of genes on a chromosome, determine what change in chromosome structure occurred. (the * indicates the centromere) before A B C D * E F G H After A B C D * E F E F G H

An inversion heterozygote contains

Inversion loops can occur in

Given the following sequence of genes on a chromosome, determine what change in chromosome structure occurred. (the * indicates the centromere) before A B C D * E F G H After A C D * E F G H

A loss of an internal piece of a chromosome is called a ________.

Which algebraic expression would be used to denote a trisomic organism?

Which type of chromosome has the longest p arm of the chromosome?

Robertsonian translocations usually occur between what types of chromosomes?

Human genetic diseases such a Cri-du-chat, Angelman syndrome and Prader-Willi syndrome are the result of which type of chromosomal change?

Familial Down syndrome is a result of

Edward and Patau syndromes are examples of ________.

Inversions are contained within what percent of the human population?

Which of the following is not an example of euploidy?

Which chromosomal change rarely has an effect on the phenotype of the individual who carries it?

The production of gene families, such as the globin genes is the result of ________.

Given the following sequence of genes on a chromosome, determine what change in chromosome structure occurred. (the * indicates the centromere) before A B C D * E F G H After A B G F E * D C H

The effects of a deficiency on an organism is dependent on the size of the deletion and the importance of the missing genetic material to the organism.

Klinefelter and Turner syndromes are examples of

A translocation cross may occur in an individual that has a(n)