Question 1

Using fetal DNA from the mother's blood for prenatal testing is a noninvasive procedure.

Accepted Answer

Fetal DNA can be detected in the mother's blood and used for prenatal testing without invasive procedures such as amniocentesis or chorionic villus sampling. This method is less risky and more easily accessible than traditional invasive methods.

Question 2

About ____ percent of children with Down syndrome are severely intellectually disabled.
A) five
B) ten
C) twenty-five
D) thirty
E) forty

Accepted Answer

B

Question 3

Submetacentric describes a chromosome whose telomeres are attached to the centromeres.

Accepted Answer

Submetacentric chromosomes have centromeres that are slightly offset, causing the chromosome to have a short arm and a long arm. The telomeres are located on the ends of the arms, not attached to the centromere. This is different from acrocentric chromosomes, which do have telomeres that attach very close to the centromere.

Question 4

Trisomy 21 is the only autosomal trisomy that allows survival into adulthood.

Accepted Answer

Trisomy 21, also known as Down syndrome, is the only autosomal trisomy that allows survival into adulthood. Other autosomal trisomies, such as trisomy 13 and trisomy 18, are usually fatal in infancy or childhood.

Question 5

Polyploidy is characterized by ____.
A) the failure of homologous chromosomes to separate properly during meiosis
B) a condition in which one chromosome is present in three copies
C) a condition in which one member of a chromosomal pair is missing
D) a chromosomal number that is not an exact multiple of the haploid set
E) a chromosomal number that is a multiple of the normal haploid chromosomal set

Accepted Answer

Polyploidy is a condition in which an organism has more than two complete sets of chromosomes. Therefore, the chromosomal number must be a multiple of the normal haploid set.

Question 6

One important difference between amniocentesis and chorionic villus sampling is that ____.
A) chorionic villus sampling is more routine
B) amniocentesis can diagnose chromosome disorders, while chorionic villus sampling cannot
C) chorionic villus sampling can be done earlier in the pregnancy than amniocentesis
D) maternal risks are higher with chorionic villus sampling
E) the risk of miscarriage is higher with amniocentesis than with chorionic villus sampling

Accepted Answer

Chorionic villus sampling can be done earlier in the pregnancy than amniocentesis. Amniocentesis is generally performed between weeks 15-20 of pregnancy, while chorionic villus sampling can be done as early as 10-13 weeks.

Question 7

Leukemia is often associated with chromosomal translocations.

Accepted Answer

Chromosomal translocations are a common genetic abnormality found in many types of leukemia, and often contribute to the development and progression of the disease.

Question 8

Chromosomes are usually studied and photographed while they are in anaphase of mitosis.

Accepted Answer

Chromosomes are usually studied and photographed during metaphase of mitosis because they are most condensed and clearly visible at this stage.

Question 9

Studies of sex chromosome aneuploidy reveal that ____ necessary for survival.
A) the X chromosome is not
B) the Y chromosome is not
C) two copies of the X chromosome are
D) two copies of the Y chromosome are
E) at least one copy of both the X and the Y chromosome is

Accepted Answer

The Y chromosome is not necessary for survival, as evidenced by individuals with Turner syndrome, who have only one X chromosome (XO) and are viable, though they may have certain health issues and infertility. This contrasts with the necessity of at least one X chromosome for survival, due to the essential genes it carries.

Question 10

The letters G,Q,R,and C,used to describe the appearance of chromosomes,refer to the ____.
A) position of the bands
B) staining procedure used to reveal the bands
C) number of arms per chromosome
D) number of centromeres per chromosome
E) position of the centromeres

Accepted Answer

The letters G, Q, R, and C refer to different staining procedures used to reveal the bands on chromosomes, allowing for the detailed study of their structure and the identification of chromosomal abnormalities. G-banding, for example, uses Giemsa stain to produce a distinct pattern of dark and light bands.

Question 11

Spindle fibers attach to the ____ of a chromosome during cell division.
A) centromere
B) telomere
C) cell membrane
D) short arms
E) gametes

Accepted Answer

Spindle fibers attach to the centromere of a chromosome during cell division to separate sister chromatids and pull them to opposite poles.

Question 12

Down syndrome can be caused by either trisomy 21 or a Robertsonian translocation.

Accepted Answer

Trisomy 21 and Robertsonian translocation are both known causes of Down syndrome. Trisomy 21 is the most common cause, accounting for about 95% of cases, while Robertsonian translocation accounts for about 4% of cases.

Question 13

When constructing a karyotype,the chromosome images are arranged in pairs according to ____________________ and ____________________.
A) size; telomere location
B) size; centromere location
C) banding pattern; centromere location
D) banding pattern; telomere location
E) size; banding pattern

Accepted Answer

Chromosomes are arranged in pairs according to size and centromere location when constructing a karyotype. This allows for easy identification and comparison of any abnormalities or differences in chromosome number or structure.

Question 14

The risk for Down syndrome increases ____.
A) when the mother is over thirty-five years old
B) when the father is over thirty-five years old
C) when the father is over fifty years old
D) for dizygotic twins
E) for monozygotic twins

Accepted Answer

The risk for Down syndrome increases when the mother is over thirty-five years old.

Question 15

Turner syndrome is not associated with intellectual disability.

Accepted Answer

Turner syndrome is not typically associated with intellectual disability, but individuals with the condition may experience some learning and attention difficulties.

Question 16

If nondisjunction occurs during meiosis I,____.
A) two gametes will be normal and two will be missing one chromosome
B) two gametes will be normal and two will have one extra chromosome
C) three gametes will be normal and one will have two extra chromosomes
D) all gametes will be normal
E) all gametes will be abnormal

Accepted Answer

Nondisjunction during meiosis I results in all gametes being abnormal because it leads to an unequal distribution of chromosomes, with two gametes having an extra chromosome and two missing one.

Question 17

Viral infections are not considered a risk factor for autosomal trisomy because a virus cannot affect human chromosome arrangement.

Accepted Answer

Viral infections during pregnancy can increase the risk of chromosomal abnormalities in the fetus, including autosomal trisomies, by causing cellular stress and potentially interfering with normal cell division and genetic material replication.

Question 18

The most common type of polyploidy in humans is ____.
A) trisomy
B) monosomy
C) triploidy
D) tetraploidy
E) haploidy

Accepted Answer

Triploidy, or having three copies of each chromosome, is the most common form of polyploidy in humans. This condition results in 69 chromosomes instead of the typical 46 and is usually fatal early in development. Trisomy (having an extra copy of one chromosome) is also a type of polyploidy but is less common than triploidy. Monosomy, tetraploidy, and haploidy are not forms of polyploidy.

Question 19

The risk of having a child with Down syndrome due to a chromosomal translocation is independent of maternal age.

Accepted Answer

The risk of having a child with Down syndrome due to a chromosomal translocation is independent of maternal age. Translocation occurs when a piece of chromosome breaks off and attaches to another chromosome, which can occur in individuals of any age. However, the risk of having a child with Down syndrome in general is higher for older mothers.

Question 20

Amniocentesis is not performed on mothers over the age of thirty-five.

Accepted Answer

This statement is false. Amniocentesis can be performed on mothers of any age, but it is more commonly recommended for mothers over the age of 35 due to increased risk of chromosomal abnormalities.

Quiz 6: Cytogenetics - Karyotypes and Chromosome Aberrations

Using fetal DNA from the mother's blood for prenatal testing is a noninvasive procedure.

About ____ percent of children with Down syndrome are severely intellectually disabled.

Submetacentric describes a chromosome whose telomeres are attached to the centromeres.

Trisomy 21 is the only autosomal trisomy that allows survival into adulthood.

Polyploidy is characterized by ____.

One important difference between amniocentesis and chorionic villus sampling is that ____.

Leukemia is often associated with chromosomal translocations.

Chromosomes are usually studied and photographed while they are in anaphase of mitosis.

Studies of sex chromosome aneuploidy reveal that ____ necessary for survival.

The letters G,Q,R,and C,used to describe the appearance of chromosomes,refer to the ____.

Spindle fibers attach to the ____ of a chromosome during cell division.

Down syndrome can be caused by either trisomy 21 or a Robertsonian translocation.

When constructing a karyotype,the chromosome images are arranged in pairs according to and .

The risk for Down syndrome increases ____.

Turner syndrome is not associated with intellectual disability.

If nondisjunction occurs during meiosis I,____.

Viral infections are not considered a risk factor for autosomal trisomy because a virus cannot affect human chromosome arrangement.

The most common type of polyploidy in humans is ____.

The risk of having a child with Down syndrome due to a chromosomal translocation is independent of maternal age.

Amniocentesis is not performed on mothers over the age of thirty-five.