Question 1

Which of the following best describes the main difference between mitosis and meiosis in terms of chromosome separation?

Accepted Answer

In mitosis, sister chromatids separate during the only division, while in meiosis, homologous chromosomes separate during Meiosis I and sister chromatids separate during Meiosis II.

Question 2

Barbara McClintock is best known for her discovery of which genetic phenomenon?

Accepted Answer

Transposable elements (jumping genes) and their role in genome evolution

Question 3

During which stage of meiosis does crossing-over (recombination) primarily occur?

Accepted Answer

Prophase I

Question 4

Why is genetic recombination during meiosis important for evolution?

Accepted Answer

It allows for the shuffling of alleles, creating novel genetic combinations that increase genetic variation.

Question 5

A chromosome is broken by radiation, resulting in a fragment that lacks a centromere. What is this fragment called, and what is its fate during cell division?

Accepted Answer

It is called an acentric fragment and is usually lost during cell division because it cannot attach to the spindle.

Question 6

Which of the following chromosomal rearrangements can result in the formation of a 'fusion gene', sometimes associated with cancer?

Accepted Answer

Translocation

Question 7

If a diploid organism has 3 pairs of chromosomes, how many possible combinations of chromosomes can be produced in its gametes due to independent assortment alone (ignoring crossing-over)?

Accepted Answer

$$2^3 = 8$

Question 8

A terminal deletion occurs on one chromosome during meiosis. What is the likely outcome for the gametes that inherit this chromosome?

Accepted Answer

They will be deficient for the deleted genes and are generally not tolerated, leading to non-viable gametes.

Question 9

Which of the following best describes a tandem duplication?

Accepted Answer

A segment of a chromosome is duplicated and the copy is inserted adjacent to the original segment.

Question 10

Which of the following is a potential evolutionary advantage of gene duplication?

Accepted Answer

It provides raw material for the evolution of new gene functions.

Question 11

A patient is found to have a chromosomal rearrangement where a segment from one chromosome is attached to a non-homologous chromosome. What type of rearrangement is this?

Accepted Answer

Translocation

Question 12

Which of the following best explains why shorter wavelength radiation is more likely to cause chromosomal breaks?

Accepted Answer

Shorter wavelengths have more energy per quantum, increasing the likelihood of breaking chemical bonds in DNA.

Question 13

During meiosis, what is the significance of chiasmata formation between homologous chromosomes?

Accepted Answer

It is the cytological evidence of crossing-over, allowing exchange of genetic material between non-sister chromatids.

Question 14

Which of the following is NOT a direct consequence of a chromosomal deletion?

Accepted Answer

Formation of a fusion gene

Question 15

A chromosome undergoes an inversion. Which of the following best describes this event?

Accepted Answer

A segment of the chromosome is reversed end to end.

Question 16

Which of the following best describes the fate of a cell lineage that is hemizygous for a terminal deletion after mitosis?

Accepted Answer

The cell lineage may survive, but may have problems depending on the genes lost.

Question 17

Which of the following is a key reason why most chromosomal deletions are not transmitted from parent to offspring?

Accepted Answer

Gametes with deletions are often non-viable due to loss of essential genes.

Question 18

Which of the following best explains why most recombination breakpoints occur within genes?

Accepted Answer

Recombination hotspots are often located within genes, increasing genetic variation at the gene level.

Question 19

If a chromosome undergoes a structural rearrangement resulting in the insertion of a segment from another chromosome, what is a possible consequence at the insertion site?

Accepted Answer

Disruption of genes at the insertion site, potentially leading to disease or altered gene function.

Chromosome Structure and Rearrangement Types: Fundamentals of Plant and Animal Genetics

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