Question 1

Which of the following best describes aneuploidy?

Accepted Answer

A condition in which the number of chromosomes is not an exact multiple of the haploid set

Question 2

A human karyotype shows 47 chromosomes with three copies of chromosome 21. What is the correct designation for this condition?

Accepted Answer

$$47, 21+$$

Question 3

Which syndrome is caused by a monosomy of the X chromosome in humans?

Accepted Answer

Turner syndrome

Question 4

What is the most likely outcome of a first-division nondisjunction event during meiosis, as shown in the first image?

Accepted Answer

Half the gametes will be trisomic and half will be monosomic

Question 5

Which of the following is a likely consequence of a chromosomal deletion?

Accepted Answer

Loss of genetic material and possible unmasking of recessive alleles

Question 6

A plant breeder observes that a new variety of strawberry is much larger than the wild type. Genetic analysis reveals it is octoploid. What is the most likely explanation for the increased size?

Accepted Answer

Polyploidy often results in larger cell and organ size due to increased gene dosage

Question 7

Which of the following best describes allopolyploidy?

Accepted Answer

Polyploidy resulting from hybridization between two different species followed by chromosome doubling

Question 8

Which chromosomal abnormality is associated with the karyotype shown in the fifth image (arrow at chromosome 21)?

Accepted Answer

Down syndrome

Question 9

Which process can lead to gene duplication within a chromosome?

Accepted Answer

Unequal crossing over during meiosis

Question 10

A patient is diagnosed with Cri du chat syndrome. Which chromosomal event is responsible for this condition?

Accepted Answer

Deletion of part of chromosome 5

Question 11

Which of the following is a possible evolutionary outcome of gene duplication?

Accepted Answer

Neofunctionalization, where one copy acquires a new function

Question 12

Which of the following is true about inversions?

Accepted Answer

They can be either paracentric (not involving the centromere) or pericentric (involving the centromere)

Question 13

What is the effect of a paracentric inversion during meiosis in a heterozygote?

Accepted Answer

It leads to the formation of dicentric and acentric chromatids, which can cause chromosome breakage

Question 14

Which of the following best describes a Robertsonian translocation?

Accepted Answer

Fusion of the long arms of two acrocentric chromosomes

Question 15

A woman has a child with Down syndrome due to a Robertsonian translocation. What is the most likely karyotype of the mother?

Accepted Answer

She is a carrier with 45 chromosomes, including a 14/21 translocation

Question 16

Which of the following is a real-world example of gene amplification?

Accepted Answer

Multiple copies of rDNA in Xenopus laevis oocytes to support high levels of protein synthesis

Question 17

Which of the following is a consequence of copy number variations (CNVs) in the human genome?

Accepted Answer

They can be associated with diseases such as cancer, autism, and cardiovascular disease

Question 18

Which of the following equations correctly represents a monosomic individual?

Accepted Answer

$$2n - 1$$

Question 19

Which of the following is a likely outcome of autopolyploidy in plants?

Accepted Answer

Increased size of flowers and fruits due to higher gene dosage

Question 20

Which of the following best explains why trisomy 21 (Down syndrome) is more common with increasing maternal age?

Accepted Answer

Older oocytes are more prone to nondisjunction during meiosis

Chromosomal Mutations: Variations in Number and Arrangement

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