Question 1

Which of the following best describes the function of telomeres in human chromosomes?

Accepted Answer

They protect chromosome ends from degradation and prevent fusion with other chromosomes.

Question 2

A karyotype analysis reveals a chromosome with a centromere located exactly in the middle, resulting in two arms of equal length. What is the classification of this chromosome?

Accepted Answer

Metacentric

Question 3

Which chromosomal abnormality is most commonly associated with Down syndrome?

Accepted Answer

Trisomy 21

Question 4

A patient is diagnosed with chronic myeloid leukemia (CML). Cytogenetic analysis reveals a reciprocal translocation between chromosomes 9 and 22. What is the resulting abnormal chromosome called?

Accepted Answer

Philadelphia chromosome

Question 5

Which of the following best explains why most autosomal monosomies (2n-1) are lethal in humans?

Accepted Answer

Loss of a chromosome leads to unmasking of recessive lethal mutations and gene dosage imbalance.

Question 6

Which experimental technique allows for the detection of submicroscopic chromosomal deletions in non-dividing cells using fluorescent probes?

Accepted Answer

FISH (Fluorescence In Situ Hybridization)

Question 7

A child is born with a karyotype 46,del(5p). Which syndrome is most likely present?

Accepted Answer

Cri du Chat syndrome

Question 8

Which of the following is a direct consequence of telomere shortening in somatic cells?

Accepted Answer

Cellular senescence and apoptosis

Question 9

A geneticist observes a chromosome with a very short p arm and a long q arm. What is the most likely classification of this chromosome?

Accepted Answer

Acrocentric

Question 10

Which of the following chromosomal changes is most likely to result in a viable human with mild or no symptoms?

Accepted Answer

Trisomy X (47,XXX)

Question 11

Which of the following best describes the difference between euchromatin and heterochromatin?

Accepted Answer

Euchromatin is lightly stained and transcriptionally active, while heterochromatin is darkly stained and transcriptionally inactive.

Question 12

A woman with Turner syndrome (45,X) is colorblind, but both her parents have normal vision. Which meiotic event most likely explains this outcome?

Accepted Answer

Nondisjunction of the X chromosome in the father during meiosis I or II

Question 13

Which of the following best describes the result of nondisjunction during meiosis II?

Accepted Answer

Two normal gametes, one gamete with an extra chromosome, and one gamete missing a chromosome.

Question 14

Which chromosomal abnormality is characterized by the karyotype 47,XXY and is associated with male infertility and distinctive body features?

Accepted Answer

Klinefelter syndrome

Question 15

Which of the following best explains why trisomy 21 is more common than other autosomal trisomies?

Accepted Answer

Chromosome 21 contains fewer genes, so gene dosage imbalance is less severe.

Question 16

Which laboratory technique is most appropriate for separating DNA fragments based on their size?

Accepted Answer

Gel electrophoresis

Question 17

A patient’s DNA is digested with a restriction enzyme and analyzed by Southern blot. The presence of multiple fragment sizes at a locus is called:

Accepted Answer

RFLP (Restriction Fragment Length Polymorphism)

Question 18

Which of the following is NOT a typical use of karyotype analysis?

Accepted Answer

Detecting point mutations

Question 19

Which chromosomal abnormality is most likely to be detected by array-CGH but missed by standard karyotyping?

Accepted Answer

A small microdeletion

Question 20

Which of the following best describes the difference between constitutive and facultative heterochromatin?

Accepted Answer

Constitutive heterochromatin is always condensed and gene-poor, while facultative heterochromatin can switch between condensed and open states.

Chromosomal Structure, Variation, and Experimental Methods in Human Genetics

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