Question 1

Which of the following best describes the difference between aneuploidy and euploidy in terms of chromosome number?

Accepted Answer

Aneuploidy refers to a change in the number of individual chromosomes, while euploidy refers to a change in the number of entire sets of chromosomes.

Question 2

A human karyotype shows 47 chromosomes, including three copies of chromosome 21. What is the genetic condition and the chromosomal terminology for this individual?

Accepted Answer

Down syndrome; trisomy

Question 3

Which of the following mechanisms can lead to autopolyploidy in plants?

Accepted Answer

Mitotic nondisjunction within the same species

Question 4

A plant species has a diploid number of $$2n = 14. A $$related species is found with $$4n = 28$$ chromosomes. What is the term for this chromosomal condition?

Accepted Answer

Tetraploidy

Question 5

Which of the following is a likely consequence of a large pericentric inversion in a chromosome during meiosis?

Accepted Answer

Half of the gametes produced will be nonviable due to abnormal synapsis.

Question 6

A karyotype shows 45 chromosomes in a human female, with only one X chromosome present. What is the most likely diagnosis?

Accepted Answer

Turner syndrome

Question 7

Which of the following best explains why aneuploidy often leads to severe phenotypic effects in animals?

Accepted Answer

Aneuploidy alters gene dosage, leading to imbalances in gene product concentrations.

Question 8

Which of the following is a real-world example of an allopolyploid crop species?

Accepted Answer

Bread wheat ($$6n = 42)$$

Question 9

A chromosome breakage event results in the reattachment of a fragment to a nonhomologous chromosome. What is this event called?

Accepted Answer

Translocation

Question 10

Which of the following statements about transposable elements is correct?

Accepted Answer

Class I elements move via an RNA intermediate and are replicative.

Question 11

Barbara McClintock discovered that the Ac element in maize can activate the movement of the Ds element. What type of transposable element are Ac and Ds?

Accepted Answer

DNA transposons

Question 12

A patient is diagnosed with cri-du-chat syndrome. Which chromosomal abnormality is most likely responsible?

Accepted Answer

Terminal deletion on chromosome 5

Question 13

Which of the following best describes the evolutionary significance of gene duplication?

Accepted Answer

Gene duplication allows for the evolution of new gene functions (neo-functionalization) or division of function (sub-functionalization).

Question 14

A chromosome rearrangement results in a segment being reversed in orientation but does not include the centromere. What is this called?

Accepted Answer

Paracentric inversion

Question 15

Which of the following is a likely outcome of a Robertsonian translocation between two acrocentric chromosomes in humans?

Accepted Answer

The chromosome number decreases by two.

Question 16

In a family study, a balanced reciprocal translocation between chromosomes 1 and 11 is found to be linked to a high incidence of psychiatric disorders. What does a LOD score of 7.1 indicate in this context?

Accepted Answer

There is significant evidence for genetic linkage between the translocation and psychiatric disorders.

Question 17

Which of the following best explains why triploid bananas are seedless and cannot reproduce sexually?

Accepted Answer

Triploid bananas have an odd number of chromosome sets, leading to unbalanced gametes during meiosis.

Question 18

Which of the following is a feature of mosaicism in humans?

Accepted Answer

Some cells have different chromosomal compositions due to mitotic nondisjunction.

Question 19

Which of the following is true about bacterial composite transposons?

Accepted Answer

They consist of two insertion sequences flanking one or more genes, often including antibiotic resistance genes.

Question 20

Which of the following best describes the mechanism of 'copy and paste' transposition?

Accepted Answer

A retrotransposon is transcribed into RNA, reverse-transcribed into DNA, and inserted at a new site, increasing copy number.

Chapter 11

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