Question 1

Which of the following best describes aneuploidy?

Accepted Answer

A condition in which there is an abnormal number of individual chromosomes, such as monosomy or trisomy

Question 2

A human karyotype shows 47 chromosomes with three copies of chromosome 21. What is the most likely diagnosis?

Accepted Answer

Down syndrome

Question 3

Which process most commonly leads to the formation of trisomic and monosomic gametes as shown in the first image?

Accepted Answer

Nondisjunction during meiosis

Question 4

Which of the following is a consequence of monosomy in humans?

Accepted Answer

It unmasks recessive alleles, potentially leading to haploinsufficiency

Question 5

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 6

Which syndrome is caused by a deletion of part of the short arm of chromosome 5?

Accepted Answer

Cri du chat syndrome

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 of the following is a real-world example of gene duplication leading to evolutionary innovation?

Accepted Answer

The evolution of hemoglobin and myoglobin from a common ancestral gene

Question 9

A karyotype shows 45 chromosomes with only one X chromosome and no second sex chromosome. What is the most likely diagnosis?

Accepted Answer

Turner syndrome

Question 10

Which of the following statements about chromosomal inversions is correct?

Accepted Answer

Inversions can lead to the formation of dicentric and acentric chromatids during meiosis

Question 11

Which equation correctly represents the chromosome number in a trisomic individual?

Accepted Answer

$$2n + 1$$

Question 12

A geneticist observes a compensation loop during meiosis. What chromosomal event most likely caused this?

Accepted Answer

Gene duplication

Question 13

Which of the following is a possible outcome of a reciprocal translocation?

Accepted Answer

Exchange of segments between two non-homologous chromosomes

Question 14

Familial Down syndrome is most often caused by which chromosomal event?

Accepted Answer

Robertsonian translocation between chromosomes 14 and 21

Question 15

Which of the following best explains why polyploidy is more common and better tolerated in plants than in animals?

Accepted Answer

Plants can often reproduce asexually and tolerate changes in gene dosage

Question 16

Which of the following is a direct consequence of nondisjunction during meiosis I, as shown in the first image?

Accepted Answer

Half the gametes are trisomic and half are monosomic

Question 17

Which of the following is a likely effect of a terminal deletion on a chromosome?

Accepted Answer

Loss of genetic material from the end of the chromosome

Question 18

Which of the following is an example of gene redundancy?

Accepted Answer

Multiple copies of rRNA genes in E. coli

Question 19

Which of the following best describes the outcome of alternate segregation in a reciprocal translocation heterozygote?

Accepted Answer

Gametes receive either both normal chromosomes or both translocated chromosomes, resulting in balanced genetic content

Question 20

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

Accepted Answer

Increased risk for certain cancers and neurological diseases

Chromosomal Mutations: Variations in Number and Arrangement

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