Question 1

Which of the following best describes aneuploidy in terms of chromosome number?

Accepted Answer

$$2n \pm 1$$

Question 2

A patient is diagnosed with Down syndrome. Which chromosomal abnormality is most likely present?

Accepted Answer

Trisomy of chromosome 21 ($$2n+1)$$

Question 3

Which mechanism most commonly leads to aneuploidy during gamete formation?

Accepted Answer

Nondisjunction

Question 4

What is the expected fertility consequence of a triploid (3n) organism undergoing meiosis?

Accepted Answer

Reduced fertility due to formation of unbalanced gametes

Question 5

Which type of polyploidy results from combining chromosome sets from two or more different species?

Accepted Answer

Allopolyploidy

Question 6

A chromosome with two breaks on either side of the centromere resulting in an inverted segment is classified as:

Accepted Answer

Pericentric inversion

Question 7

Which chromosomal event is most likely to result in pseudodominance?

Accepted Answer

Deletion uncovering a recessive allele

Question 8

A Robertsonian translocation typically results in which of the following?

Accepted Answer

Fusion of two acrocentric chromosomes and reduction in chromosome number

Question 9

Which cytological technique is commonly used to detect microdeletions and microduplications in chromosomes?

Accepted Answer

Fluorescent In Situ Hybridization (FISH)

Question 10

In a partial deletion heterozygote, what structure is observed during meiosis that helps identify the deletion?

Accepted Answer

Unpaired loop

Question 11

Which of the following is a direct consequence of a chromosomal break that disrupts a gene?

Accepted Answer

Loss of function

Question 12

A plant breeder wants to create seedless fruit. Which ploidy level should they aim for in the fruit-producing plants?

Accepted Answer

Triploid ($$3n)$$

Question 13

Which chromosomal rearrangement involves swapping of chromosome arms between non-homologous chromosomes?

Accepted Answer

Reciprocal balanced translocation

Question 14

Which of the following is TRUE regarding gene dosage effects in monosomy versus trisomy?

Accepted Answer

Monosomy is often lethal due to insufficient gene dosage

Question 15

A hybrid plant has a chromosome composition of $$2nA + 2nB. $$What is the expected fertility status?

Accepted Answer

Fertile due to formation of only bivalents

Question 16

Which of the following is a benefit of allopolyploidy in agriculture?

Accepted Answer

Increased heterozygosity

Question 17

Transposable elements make up a significant portion of the human genome. Which two major types are found in humans?

Accepted Answer

LINE and SINE

Question 18

During meiosis in a triploid organism, which synaptic structure is most likely to form?

Accepted Answer

Bivalents and trivalents

Question 19

Which chromosomal abnormality is most likely to result from unequal crossing over?

Accepted Answer

Interstitial duplication or deletion

Question 20

A patient’s karyotype shows mosaicism for the X chromosome. Which cellular event most likely caused this?

Accepted Answer

Mitotic nondisjunction

Chromosomal Aberrations: Variation at the Chromosome Level (Chapter 10 Study Notes)

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