Question 1

Which of the following best describes the difference between euchromatin and heterochromatin in eukaryotic cells?

Accepted Answer

Euchromatin is loosely packed and transcriptionally active, while heterochromatin is tightly packed and transcriptionally inactive.

Question 2

A population of 100 individuals has the following genotypes for a gene: 40 AA, 40 Aa, and 20 aa. What is the frequency of the 'A' allele in this population?

Accepted Answer

0.6

Question 3

Which enzyme is responsible for adding phosphate groups to proteins during cell signaling?

Accepted Answer

Kinase

Question 4

In the context of the lac operon, what happens when lactose is present and glucose is absent?

Accepted Answer

The lac operon is fully activated, leading to high transcription of lac genes.

Question 5

Which of the following best explains the mechanism of replicative transposition?

Accepted Answer

The transposon is copied, and the new copy is inserted into a new site while the original remains.

Question 6

A woman with genotype $$I^A I^O ($$blood type A) and a man with genotype $$I^B I^O ($$blood type B) have a child. What are the possible blood types of their child?

Accepted Answer

A, B, AB, and O

Question 7

Which of the following is a post-translational modification that can target a protein for degradation?

Accepted Answer

Ubiquitination

Question 8

In a dihybrid cross between two heterozygous plants ($$AaBb 	imes AaBb$$), what is the expected phenotypic ratio in the F2 generation, assuming independent assortment?

Accepted Answer

$$9:3:3:1$$

Question 9

Which of the following best describes the function of telomerase in eukaryotic cells?

Accepted Answer

It extends the telomeres by adding repetitive DNA sequences to the ends of chromosomes.

Question 10

Which of the following is a mechanism by which siRNA regulates gene expression?

Accepted Answer

siRNA binds to mRNA and promotes its degradation.

Question 11

A mutation changes a codon from $$UAA to$$ $$CAA. $$What type of mutation is this?

Accepted Answer

Missense mutation

Question 12

Which of the following best describes the concept of genetic drift?

Accepted Answer

A change in allele frequencies due to random sampling effects in small populations.

Question 13

Which of the following is NOT a prezygotic reproductive isolating mechanism?

Accepted Answer

Hybrid sterility

Question 14

Which of the following statements about the Hardy-Weinberg equilibrium is correct?

Accepted Answer

It predicts that allele and genotype frequencies will remain constant from generation to generation in the absence of evolutionary forces.

Question 15

Which of the following best describes the outcome of a double crossover event between three linked genes?

Accepted Answer

The middle gene is exchanged between chromatids, resulting in recombinant gametes.

Question 16

Which of the following is a feature of class I transposons?

Accepted Answer

They transpose via an RNA intermediate.

Question 17

Which of the following best describes the effect of DNA methylation on gene expression in eukaryotes?

Accepted Answer

DNA methylation generally represses gene expression by preventing transcription.

Question 18

Which of the following is the correct formula for calculating allelic frequency from genotype counts in a population?

Accepted Answer

$$p = \frac{2N_{AA} + N_{Aa}}{2N_{total}}$$

Question 19

Which of the following best describes the function of the operator in the lac operon?

Accepted Answer

It is the site where the repressor protein binds to regulate transcription.

Question 20

Which of the following is an example of a dominant epistasis interaction?

Accepted Answer

A dominant allele at one locus masks the expression of alleles at a second locus.

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