Question 1

Which of the following best explains why position effect variation provided the first evidence that chromatin compaction affects gene expression?

Accepted Answer

It demonstrated that the physical location of a gene within the chromatin could influence whether the gene is expressed or silenced.

Question 2

In areas of active gene expression, chromatin is typically:

Accepted Answer

Decondensed, allowing access to transcription machinery.

Question 3

Which chemical modification of DNA is most directly associated with gene silencing?

Accepted Answer

Methylation of CpG sequences

Question 4

Histone modifications most commonly occur on which part of the histone protein?

Accepted Answer

The N-terminal 'tails'

Question 5

Which of the following is an example of an epigenetic change?

Accepted Answer

Methylation of cytosine residues in DNA

Question 6

A scientist observes that certain patches of cells in a fruit fly are the same color, rather than a random mix. What is the most likely explanation for this observation?

Accepted Answer

Heritable chromatin state established during development

Question 7

Which of the following best describes the effect of acetylation on histone tails?

Accepted Answer

It neutralizes the positive charge, loosening DNA-histone interaction and promoting gene expression.

Question 8

Mendel’s success in his genetic experiments was largely due to his use of:

Accepted Answer

Traits with distinguishable phenotypes and pure-breeding strains

Question 9

Which of the following is NOT a feature of Mendel’s experimental design?

Accepted Answer

Selection of traits with continuous variation

Question 10

A test cross is used to:

Accepted Answer

Determine the genotype of an individual with a dominant phenotype

Question 11

If a plant with genotype $Yy$ (yellow seeds) is test-crossed with a plant with genotype $yy$ (green seeds), what is the expected phenotypic ratio in the offspring?

Accepted Answer

$1$ yellow : $1$ green

Question 12

Which of the following best describes Mendel’s Law of Segregation at the molecular level?

Accepted Answer

Alleles of a gene separate during gamete formation so that each gamete receives only one allele.

Question 13

In a dihybrid cross involving two independently assorting loci, what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

$9:3:3:1$

Question 14

Which of the following statements about reciprocal crosses is correct?

Accepted Answer

They are used to determine if a trait is sex-linked.

Question 15

Which of the following is a consequence of DNA methylation at CpG islands in gene promoters?

Accepted Answer

Gene silencing

Question 16

A plant heterozygous for two genes ($AaBb$) is self-crossed. What is the probability of obtaining an offspring that is homozygous recessive for both genes ($aabb$)?

Accepted Answer

$1/16$

Question 17

Which of the following best describes the role of nucleosome displacement in gene regulation?

Accepted Answer

It opens chromatin, allowing transcription factors to access DNA.

Question 18

Which of the following is an example of a heritable epigenetic change that does NOT alter the DNA sequence?

Accepted Answer

Histone methylation

Question 19

In Mendel’s experiments, why was it important to use pure-breeding strains?

Accepted Answer

To ensure that the parental generation was genetically identical for the trait being studied

Question 20

Which of the following best explains why chromatin state can be considered heritable?

Accepted Answer

Chromatin modifications can be passed from parent to daughter cells during cell division.

Chromatin Structure, Epigenetics, and Mendelian Transmission Genetics

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