Question 1

Which of the following best describes the difference between a reciprocal (balanced) translocation and a Robertsonian (non-reciprocal) translocation?

Accepted Answer

Reciprocal translocation is an equal exchange of chromosomal material between two non-homologous chromosomes, while Robertsonian translocation involves the fusion of the long arms of two acrocentric chromosomes and loss of their short arms.

Question 2

A female patient is diagnosed with Charcot-Marie-Tooth disease due to a duplication on the p arm of chromosome 17. What is her karyotype notation?

Accepted Answer

$$46; XX; 17p+$$

Question 3

Which chromosomal abnormality is most commonly associated with the clinical features of a cat-like cry, severe cognitive delays, and a deletion on chromosome 5?

Accepted Answer

Cri-du-chat syndrome

Question 4

A karyotype shows 45 chromosomes with a translocation between chromosomes 14 and 21. The individual is phenotypically normal. What is the most likely diagnosis?

Accepted Answer

$$45; XX; t(14,21)$$

Question 5

Which of the following best explains why individuals with Turner syndrome (45, X0) exhibit short stature and webbed neck?

Accepted Answer

They lack one X chromosome, resulting in haploinsufficiency for genes that escape X-inactivation.

Question 6

Which cytogenetic technique uses fluorescent probes to detect specific DNA sequences on chromosomes and is useful for identifying microdeletions?

Accepted Answer

Fluorescent in situ hybridization (FISH)

Question 7

A child is born with the karyotype $$47; XX; +21. $$Which syndrome does this child have, and what is the underlying chromosomal abnormality?

Accepted Answer

Down syndrome; trisomy 21

Question 8

Which of the following is a consequence of gene duplication?

Accepted Answer

It can result in gene redundancy and provide raw material for evolution.

Question 9

What is the most likely outcome if non-disjunction occurs during meiosis II in oogenesis?

Accepted Answer

Half of the gametes will be normal, and the other half will have either an extra or missing chromosome.

Question 10

Which of the following karyotypes corresponds to a male with Klinefelter syndrome?

Accepted Answer

$$47; XXY$$

Question 11

A plant species is found to have four sets of chromosomes, all derived from the same species. What is the correct term for this condition?

Accepted Answer

Autopolyploidy

Question 12

Which of the following statements about G-banding is correct?

Accepted Answer

G-banding is performed by staining chromosomes with Geimsa after trypsin digestion.

Question 13

A karyotype shows a deletion on the short arm of chromosome 4. Which syndrome is most likely present, and what is a key clinical feature?

Accepted Answer

Wolf-Hirschhorn syndrome; prominent forehead and seizures

Question 14

Which of the following best describes the difference between euploidy and aneuploidy?

Accepted Answer

Euploidy is the presence of complete sets of chromosomes, while aneuploidy is the presence of an abnormal number of chromosomes that is not a complete set.

Question 15

Which prenatal test involves sampling placental tissue to detect chromosomal abnormalities?

Accepted Answer

Chorionic villus sampling (CVS)

Question 16

A karyotype shows $$47; XY; +13. $$What syndrome does this represent, and what is a common clinical feature?

Accepted Answer

Patau syndrome; mental and physical retardation

Question 17

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

Accepted Answer

It can lead to the production of gametes with duplications and deletions if crossing over occurs within the inversion loop.

Question 18

Which of the following best explains the concept of mosaicism?

Accepted Answer

Some cells in the organism are normal, while others have a chromosomal abnormality due to non-disjunction in mitosis.

Question 19

Which of the following karyotypes would be expected in a human somatic cell?

Accepted Answer

$$46; XY$$

Question 20

Which of the following is NOT a typical consequence of chromosomal duplication?

Accepted Answer

Immediate lethality in all cases

Chromosome Structure, Banding, and Abnormalities in Eukaryotes

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