Question 1

Which of the following best describes a segmental deletion in a chromosome?

Accepted Answer

A loss of a small terminal portion of a chromosome, often resulting in partial monosomy for that segment.

Question 2

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

Accepted Answer

An increase in the number of gene copies, potentially amplifying gene expression.

Question 3

A patient is diagnosed with myoclonic epilepsy with ragged red fibers (MERRF). Which type of genetic inheritance is most likely responsible for this disorder?

Accepted Answer

Mitochondrial inheritance

Question 4

Which experiment provided the first strong evidence that DNA is the genetic material?

Accepted Answer

Avery, MacLeod, and McCarty's transformation experiment

Question 5

Which of the following best describes a nonreciprocal translocation?

Accepted Answer

Transfer of a segment from one chromosome to another nonhomologous chromosome, with only one chromosome gaining genetic material.

Question 6

A child is born with Down syndrome due to a Robertsonian translocation. Which of the following karyotypes is most likely?

Accepted Answer

46 chromosomes, with three copies of chromosome 21, one of which is translocated to chromosome 14

Question 7

Which of the following statements about fragile X syndrome is correct?

Accepted Answer

It is associated with a fragile site on the X chromosome and is the most common form of inherited mental retardation.

Question 8

Which of the following best explains why duplications can be beneficial in evolution?

Accepted Answer

Duplications provide extra copies of genes, allowing one copy to mutate and potentially acquire new functions.

Question 9

Which of the following is a key feature of paracentric inversions?

Accepted Answer

They do not include the centromere within the inverted segment.

Question 10

Which of the following best describes the hyperchromic shift observed in DNA?

Accepted Answer

A decrease in DNA viscosity and an increase in UV absorption as DNA denatures.

Question 11

A geneticist observes that a certain gene is present in multiple copies in the genome due to a duplication event. Which of the following is a possible outcome of this event?

Accepted Answer

One copy may acquire a new function through mutation, while the other retains the original function.

Question 12

Which of the following equations correctly represents the calculation of the number of possible gametes produced by an organism with $n$ heterozygous gene pairs?

Accepted Answer

$2^n$

Question 13

Which of the following is true regarding the inheritance of mitochondrial DNA?

Accepted Answer

It is inherited exclusively from the mother.

Question 14

Which of the following best describes a reciprocal translocation?

Accepted Answer

Segments from two nonhomologous chromosomes are exchanged with each other.

Question 15

Which of the following is a likely result of crossing over within a paracentric inversion during meiosis?

Accepted Answer

Production of dicentric and acentric chromatids, leading to nonviable gametes.

Question 16

Which of the following statements about gene duplication and evolution is correct?

Accepted Answer

Gene duplication can provide raw material for the evolution of new gene functions.

Question 17

Which of the following is a characteristic of a fragile site on a chromosome?

Accepted Answer

It is a region that stains lightly and is prone to breakage under certain conditions.

Question 18

Which of the following best explains why heterozygotes for a chromosomal inversion may have reduced fertility?

Accepted Answer

Crossing over within the inversion loop can produce unbalanced gametes.

Question 19

Which of the following is the most likely effect of a Robertsonian translocation involving chromosomes 14 and 21 in a carrier parent?

Accepted Answer

Increased risk of producing offspring with Down syndrome.

Question 20

Which of the following best describes the function of the FHIT gene located in the FRA3B fragile site?

Accepted Answer

It is involved in increasing mutation and deletions, and is often altered in lung cancer.

Chromosomal Aberrations, Gene Duplication, and Fragile Sites: Genetics Study Notes

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