Question 1

Which of the following best describes aneuploidy?

Accepted Answer

A condition in which one or more individual chromosomes are added or missing from the normal set

Question 2

A child is born with Down syndrome. Which chromosomal abnormality is most likely responsible?

Accepted Answer

A trisomy of chromosome 21

Question 3

Which of the following chromosomal rearrangements can result in a gene being placed next to a highly active promoter, potentially causing cancer?

Accepted Answer

Translocation

Question 4

Cri du chat syndrome is caused by which chromosomal abnormality?

Accepted Answer

A deletion on chromosome 5

Question 5

Which of the following best explains why polyploidy is common in plants but rare in animals?

Accepted Answer

Plants can tolerate extra sets of chromosomes, while animals usually cannot survive such changes

Question 6

A color-blind girl with Turner syndrome (XO) is born to a color-blind man and a phenotypically normal woman. Which event most likely explains her genotype?

Accepted Answer

Non-disjunction during oogenesis in the mother, resulting in an egg with no sex chromosome

Question 7

Which of the following is a consequence of a pericentric inversion?

Accepted Answer

The centromere is included within the inverted segment

Question 8

Which of the following equations correctly represents the chromosome number in a trisomic individual?

Accepted Answer

$$2n + 1$$

Question 9

Colchicine is used in plant breeding to induce polyploidy. What is its mechanism of action?

Accepted Answer

It arrests cells in metaphase, preventing spindle formation and chromosome separation

Question 10

A karyotype analysis reveals a patient with 47 chromosomes, including three copies of chromosome 18. What is the diagnosis?

Accepted Answer

Edward syndrome

Question 11

Which of the following is a likely outcome of a crossover event within a paracentric inversion during meiosis?

Accepted Answer

Production of gametes with duplications and deletions

Question 12

Which of the following best describes a duplication event in a chromosome?

Accepted Answer

A segment of the chromosome is present in two copies

Question 13

A plant breeder wants to create a tetraploid plant. If the diploid number is $$2n = 14$$, what will be the chromosome number in the tetraploid plant?

Accepted Answer

$$4n = 28$$

Question 14

Which of the following is a common feature of individuals with Patau syndrome?

Accepted Answer

Cleft lip and palate, polydactyly, and severe intellectual disability

Question 15

Which of the following best explains why the risk of Down syndrome increases with maternal age?

Accepted Answer

Non-disjunction events during oogenesis increase with maternal age

Question 16

Which of the following is NOT a possible result of a chromosomal translocation?

Accepted Answer

Duplication of a chromosome segment

Question 17

Which of the following is the correct formula for the chromosome number in a monosomic individual?

Accepted Answer

$$2n - 1$$

Question 18

Which of the following statements about karyotypes is correct?

Accepted Answer

Karyotypes can reveal large-scale chromosomal abnormalities such as deletions, duplications, and aneuploidy

Question 19

Which of the following is a likely agricultural benefit of polyploidy in plants?

Accepted Answer

Increased vigor and larger fruit size

Question 20

Which of the following best describes the difference between tandem and displaced duplications?

Accepted Answer

Tandem duplications are adjacent to the original segment, while displaced duplications are located elsewhere on the same or a different chromosome

Chromosome Abnormalities: Structure and Number Variations

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