Question 1

Which of the following best describes aneuploidy?

Accepted Answer

A variation in chromosome number where an organism gains or loses one or more chromosomes, but not a complete set.

Question 2

A human cell with a chromosome complement of $$2n-1 is $$best described as:

Accepted Answer

Monosomic

Question 3

Which event during meiosis most commonly leads to the formation of gametes with an abnormal number of chromosomes?

Accepted Answer

Nondisjunction

Question 4

Down syndrome is most often caused by which chromosomal abnormality?

Accepted Answer

Trisomy of chromosome 21

Question 5

Which of the following statements about polyploidy is correct?

Accepted Answer

Polyploidy refers to the presence of more than two sets of chromosomes.

Question 6

A plant species with a chromosome number of $$4n is $$best described as:

Accepted Answer

Tetraploid

Question 7

Which of the following chromosomal changes does NOT alter the total amount of genetic information, but only its arrangement?

Accepted Answer

Inversion

Question 8

A segment of a chromosome is present more than once in the genome. This is known as:

Accepted Answer

Duplication

Question 9

Which syndrome is associated with a segmental deletion of the small terminal part of chromosome 5?

Accepted Answer

Cri du chat syndrome

Question 10

Which of the following is a consequence of a paracentric inversion crossover during meiosis?

Accepted Answer

Formation of a dicentric and an acentric chromatid

Question 11

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

Accepted Answer

Robertsonian translocation involving chromosome 21

Question 12

Which of the following best describes haploinsufficiency?

Accepted Answer

A condition where one copy of a gene is not sufficient for normal function or survival.

Question 13

Which chromosomal abnormality is most commonly found in spontaneously aborted human fetuses?

Accepted Answer

Trisomy

Question 14

Which of the following is a mechanism that can lead to gene duplication?

Accepted Answer

Unequal crossing over during meiosis

Question 15

A reciprocal translocation involves:

Accepted Answer

Exchange of segments between two nonhomologous chromosomes

Question 16

Which of the following is true about the Down syndrome critical region (DSCR)?

Accepted Answer

It is a region on chromosome 21 containing dosage-sensitive genes responsible for many Down syndrome phenotypes.

Question 17

Which diagnostic technique is considered noninvasive for prenatal genetic diagnosis?

Accepted Answer

Noninvasive prenatal genetic diagnosis (NIPGD)

Question 18

Which of the following best describes allopolyploidy?

Accepted Answer

Combination of chromosome sets from different species as a consequence of hybridization

Question 19

Which chromosomal rearrangement is most likely to result in a compensation loop during meiosis?

Accepted Answer

Intercalary deletion

Question 20

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

Accepted Answer

The presence of genes encoding both trypsin and chymotrypsin, which share sequence similarity but have distinct functions.

Chromosome Mutations: Variation in Number and Arrangement

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