Question 1

Which chromosomal modification is most likely to result in a lethal phenotype in humans, but is better tolerated in plants?

Accepted Answer

Monosomy (2n - 1)

Question 2

A child is born with three copies of chromosome 21. What is the chromosomal formula for this condition?

Accepted Answer

$$47, 21+$$

Question 3

Which of the following best describes polyploidy?

Accepted Answer

An organism has more than two complete sets of chromosomes

Question 4

What is the most common cause of Down syndrome?

Accepted Answer

Nondisjunction during meiosis resulting in trisomy 21

Question 5

Which chromosomal aberration involves the loss of a segment from the interior of a chromosome?

Accepted Answer

Intercalary deletion

Question 6

A plant species with a diploid number of 12 produces a triploid offspring. What is the chromosome number of the triploid?

Accepted Answer

$$18$$

Question 7

Which of the following is a consequence of crossing over within a paracentric inversion loop?

Accepted Answer

Production of one dicentric and one acentric chromatid

Question 8

What is the effect of colchicine on a diploid cell undergoing mitosis?

Accepted Answer

It doubles the chromosome number by preventing spindle formation

Question 9

Which chromosomal aberration is associated with the 'cry of the cat' syndrome?

Accepted Answer

Intercalary deletion of chromosome 5p

Question 10

Gene redundancy is most commonly observed in which type of gene?

Accepted Answer

Ribosomal RNA (rRNA) genes

Question 11

Which chromosomal modification is a source of genetic variability during evolution?

Accepted Answer

Duplication

Question 12

A reciprocal translocation between two nonhomologous chromosomes results in which of the following during meiosis?

Accepted Answer

Production of genetically unbalanced gametes

Question 13

Which term describes an organism with two complete sets of chromosomes from two different species?

Accepted Answer

Allotetraploid (amphidiploid)

Question 14

What is the chromosomal formula for a monosomic individual?

Accepted Answer

$$2n - 1$$

Question 15

Which chromosomal aberration is most likely to result in a compensation loop during synapsis?

Accepted Answer

Duplication

Question 16

Which syndrome is associated with a folate-sensitive fragile site on the X chromosome and intellectual disability?

Accepted Answer

Fragile-X syndrome

Question 17

A plant breeder wants to create a new fertile hybrid species by crossing two related species and doubling the chromosome number. What is the resulting organism called?

Accepted Answer

Amphidiploid

Question 18

Which chromosomal aberration is most likely to be associated with both positive and negative effects on human health, including autism and cardiovascular disease?

Accepted Answer

Copy Number Variants (CNVs)

Question 19

Which of the following best describes alternate segregation in a reciprocal translocation heterozygote?

Accepted Answer

It produces normal and balanced gametes

Question 20

Which gene is located within a fragile site on chromosome 3p and is often altered or missing in lung cancer cells?

Accepted Answer

FHIT

Ch6 Chromosome Mutations: Variation in Number and Arrangement

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