Question 1

Which of the following best describes the function of the lac operon in E. coli?

Accepted Answer

It allows the bacterium to break down lactose only when lactose is present and glucose is absent.

Question 2

A mutation causes the repressor protein of the trp operon to be unable to bind tryptophan. What is the most likely consequence?

Accepted Answer

The trp operon will be constitutively expressed, even when tryptophan is abundant.

Question 3

Which of the following is a key difference between gene regulation in prokaryotes and eukaryotes?

Accepted Answer

Prokaryotes regulate gene expression primarily at the level of transcription, while eukaryotes use multiple levels including chromatin modification.

Question 4

DNA methylation in eukaryotes typically results in:

Accepted Answer

Decreased transcription of the methylated gene.

Question 5

A scientist discovers a eukaryotic gene that is highly expressed only when its associated histones are acetylated. What is the most likely explanation for this observation?

Accepted Answer

Histone acetylation relaxes chromatin structure, making DNA more accessible for transcription.

Question 6

Which of the following best describes the role of microRNAs (miRNAs) in gene regulation?

Accepted Answer

miRNAs bind to mRNA and can inhibit translation or lead to mRNA degradation.

Question 7

A patient is diagnosed with cancer due to a mutation in a proto-oncogene. Which of the following best explains how this mutation could lead to cancer?

Accepted Answer

The mutation causes the proto-oncogene to become an oncogene, leading to uncontrolled cell division.

Question 8

Which of the following statements about viral genomes is correct?

Accepted Answer

Viral genomes can be composed of either DNA or RNA, and can be single- or double-stranded.

Question 9

During the lytic cycle of a bacteriophage, which of the following events occurs?

Accepted Answer

The host cell is lysed, releasing new viral particles.

Question 10

A virus with a single-stranded RNA genome that serves directly as mRNA for protein synthesis is classified as which class according to the Baltimore classification?

Accepted Answer

Class IV

Question 11

Which of the following best explains why retroviruses, such as HIV, are difficult to eradicate from the human body?

Accepted Answer

They integrate their genetic material into the host genome, forming a provirus.

Question 12

Which of the following is a real-world application of CRISPR gene editing technology?

Accepted Answer

Precisely modifying specific DNA sequences in living organisms.

Question 13

A researcher uses next-generation sequencing to analyze a patient's genome. Which of the following best describes the advantage of this technology?

Accepted Answer

It allows rapid and large-scale sequencing of entire genomes.

Question 14

Which of the following best describes the process of reproductive cloning in animals?

Accepted Answer

Transferring the nucleus of a somatic cell into an enucleated egg cell to produce a genetically identical organism.

Question 15

Embryonic stem cells are considered pluripotent because:

Accepted Answer

They can differentiate into any cell type in the body.

Question 16

A scientist is studying a gene that is silenced in cancer cells due to DNA methylation. Which technique could be used to determine the methylation status of this gene?

Accepted Answer

Bisulfite sequencing

Question 17

Which of the following equations correctly represents the relationship between the number of viral particles ($$N$$), the initial number of viruses ($$N_0$$), and the number of replication cycles ($$n$$), assuming each cycle doubles the number of viruses?

Accepted Answer

$$N = N_0$ 	imes 2^n$$

Question 18

A plant biologist wants to create a genetically identical population of a rare orchid. Which biotechnology technique should they use?

Accepted Answer

Reproductive cloning of plants via tissue culture.

Question 19

Which of the following scenarios best illustrates the use of RNA interference (RNAi) in medicine?

Accepted Answer

Using small interfering RNAs (siRNAs) to silence the expression of a disease-causing gene.

Question 20

A patient receives a vaccine containing inactivated viral particles. Which immune response is primarily stimulated by this vaccine?

Accepted Answer

The production of memory B cells and antibodies specific to the virus.

Regulation of Gene Expression, Viruses, and Biotechnology: Study Notes

Study Guide - Practice Questions

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