Question 1

Which of the following best describes aneuploidy?

Accepted Answer

A condition in which cells contain a number of chromosomes that is not a complete set, such as 2n+1 or 2n-1

Question 2

A human zygote with a karyotype of 47,XX,+21 is an example of which genetic condition?

Accepted Answer

Down syndrome

Question 3

Which of the following is a likely consequence of nondisjunction during meiosis I?

Accepted Answer

All gametes will be aneuploid, with half being n+1 and half being n-1

Question 4

Which syndrome is caused by monosomy of the X chromosome (45,XO) in humans?

Accepted Answer

Turner syndrome

Question 5

What is the gene dosage in a trisomic individual compared to a normal diploid for the affected chromosome?

Accepted Answer

$$150\%$$

Question 6

Which of the following best explains why most autosomal monosomies are not observed in live human births?

Accepted Answer

Monosomy causes severe gene dosage imbalance, leading to embryonic lethality

Question 7

A partial deletion heterozygote is best described as:

Accepted Answer

An individual with one normal chromosome and one chromosome missing a segment

Question 8

Which molecular technique is most suitable for detecting microdeletions or microduplications that are too small to be seen by microscopy?

Accepted Answer

Fluorescent in situ hybridization (FISH)

Question 9

In a paracentric inversion heterozygote, what is the outcome of a single crossover event within the inversion loop during meiosis?

Accepted Answer

Two gametes are viable (one normal, one inversion), and two are inviable due to deletions

Question 10

Which of the following is a possible outcome of alternate segregation in a reciprocal balanced translocation heterozygote?

Accepted Answer

Gametes with a full haploid set of genes

Question 11

Familial Down syndrome is most commonly caused by which chromosomal abnormality?

Accepted Answer

Robertsonian translocation between chromosome 21 and another acrocentric chromosome

Question 12

Which of the following best describes uniparental disomy?

Accepted Answer

Both copies of a chromosome are inherited from one parent

Question 13

What is the most likely result of a crossover event within a pericentric inversion loop?

Accepted Answer

Two gametes with duplications and deletions, and two normal gametes

Question 14

Which of the following is a real-world example of a syndrome caused by an interstitial deletion?

Accepted Answer

WAGR syndrome

Question 15

A female with Turner syndrome is found to have some cells with 45,XO and some with 46,XX. This is an example of:

Accepted Answer

Mosaicism

Question 16

Which of the following is a likely consequence of a large terminal deletion on one chromosome in a diploid organism?

Accepted Answer

The organism will be a partial deletion heterozygote

Question 17

Which of the following best explains why plants are generally more tolerant of gene dosage changes than animals?

Accepted Answer

Plants are less sensitive to gene balance and dosage effects

Question 18

What is the expected outcome of meiosis in a trisomic individual?

Accepted Answer

Gametes will be produced in a 2:1 ratio, with two carrying two chromosomes and one carrying one chromosome

Question 19

Which of the following is a mechanism by which chromosome number can evolve in related organisms?

Accepted Answer

Robertsonian translocation

Question 20

A crossover between misaligned repetitive regions of homologous chromosomes is most likely to result in:

Accepted Answer

A partial duplication and a partial deletion

Chromosomal Abnormalities: Aneuploidy, Structural Variations, and Their Genetic Consequences

Study Guide - Practice Questions