Question 1

Which of the following statements best describes the difference between prokaryotic and eukaryotic genomes?

Accepted Answer

Prokaryotic genomes are generally less complex, often consist of a single circular chromosome located in the nucleoid, and may include plasmids, whereas eukaryotic genomes are more complex, have multiple linear chromosomes located in the nucleus, and rarely include plasmids.

Question 2

Which of the following nucleotides is present in RNA but not in DNA?

Accepted Answer

Uracil

Question 3

During DNA replication, which enzyme is responsible for synthesizing short RNA primers needed to initiate DNA synthesis?

Accepted Answer

Primase

Question 4

A scientist is studying a gene that is methylated in a bacterial cell. What is the most likely effect of this methylation?

Accepted Answer

The gene will be silenced or have reduced expression.

Question 5

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 6

Which type of mutation is most likely to result in a truncated (shortened) protein product?

Accepted Answer

Nonsense mutation

Question 7

A researcher exposes bacterial cells to UV light, resulting in the formation of thymine dimers. Which cellular process is most directly responsible for repairing these lesions?

Accepted Answer

Nucleotide excision repair

Question 8

Which of the following statements about mRNA, tRNA, and rRNA is correct?

Accepted Answer

Only mRNA is translated into protein; tRNA and rRNA function as RNA molecules.

Question 9

In the process of translation, what is the function of the start codon, and what is its typical RNA sequence?

Accepted Answer

It signals the beginning of translation; AUG

Question 10

Which of the following best describes the difference between leading and lagging strands during DNA replication?

Accepted Answer

The leading strand is synthesized continuously in the direction of the replication fork, while the lagging strand is synthesized discontinuously away from the replication fork in short fragments called Okazaki fragments.

Question 11

A bacterial cell acquires a gene for antibiotic resistance from another cell via a pilus. Which type of horizontal gene transfer is this?

Accepted Answer

Conjugation

Question 12

Which of the following best explains the redundancy of the genetic code?

Accepted Answer

Multiple codons can encode the same amino acid.

Question 13

Which enzyme is responsible for joining Okazaki fragments on the lagging strand during DNA replication?

Accepted Answer

Ligase

Question 14

A scientist is using the Ames test in the laboratory. What is the primary purpose of this test?

Accepted Answer

To assess the mutagenic potential of chemical compounds

Question 15

Which of the following statements about plasmids is correct?

Accepted Answer

Plasmids often carry genes that confer advantages such as antibiotic resistance or toxin production.

Question 16

Which of the following best describes the function of small non-coding RNAs in bacteria?

Accepted Answer

They bind to mRNA to inhibit translation or promote degradation, thus regulating protein synthesis.

Question 17

A patient is infected with a bacterium that can sense the density of its population and coordinate gene expression accordingly. What is this process called?

Accepted Answer

Quorum sensing

Question 18

Which class of transposons utilizes reverse transcriptase to make cDNA from an RNA intermediate?

Accepted Answer

Retrotransposons

Question 19

In eukaryotic cells, what is the difference between exons and introns?

Accepted Answer

Exons are coding regions that remain in the mature mRNA, while introns are non-coding regions removed during RNA processing.

Question 20

A bacteriophage transfers genetic material from one bacterium to another. What is this process called?

Accepted Answer

Transduction

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