Question 1

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

Accepted Answer

Information flows from DNA to RNA to proteins.

Question 2

A scientist exposes a bacterial culture to UV light, resulting in a mutation that changes a codon from UAU (tyrosine) to UAA (stop codon). What type of mutation has occurred?

Accepted Answer

Nonsense mutation

Question 3

During DNA replication in bacteria, which enzyme is responsible for unwinding the DNA double helix to create the replication fork?

Accepted Answer

Helicase

Question 4

A patient is diagnosed with tuberculosis. Which of the following bacteria is most likely responsible, and what is a key structural feature of this organism?

Accepted Answer

Mycobacterium; waxy cell wall rich in mycolic acids

Question 5

Which of the following best explains why prokaryotic cells are often used for the production of recombinant proteins in biotechnology?

Accepted Answer

They are inexpensive and grow rapidly, allowing efficient protein production.

Question 6

A researcher wants to insert a human gene into a bacterial plasmid. Which combination of enzymes is required for this process?

Accepted Answer

Restriction enzyme and ligase

Question 7

Which of the following statements about the lac operon in E. coli is correct?

Accepted Answer

It is an inducible operon activated by the presence of lactose, which binds to the repressor.

Question 8

Which of the following best describes the process of bacterial conjugation?

Accepted Answer

Transfer of genetic material between bacteria via a pilus

Question 9

A patient presents with symptoms of cholera after drinking contaminated water. Which Gram-negative bacterium is most likely responsible, and what is a key feature of its cell wall?

Accepted Answer

Vibrio; outer membrane with lipopolysaccharide (LPS)

Question 10

Which of the following is a correct statement about the classification of organisms?

Accepted Answer

Classification uses genetic information such as rRNA sequences, as well as biochemical and morphological characteristics.

Question 11

A scientist is using a dichotomous key to identify an unknown bacterium. Which of the following best describes how a dichotomous key works?

Accepted Answer

It uses a series of yes/no questions based on experimental results.

Question 12

Which of the following is a unique feature of archaea compared to bacteria?

Accepted Answer

They often live in extreme environments such as high salt or temperature.

Question 13

A patient develops paralytic shellfish poisoning after eating contaminated seafood. Which group of organisms is responsible for producing the toxins involved?

Accepted Answer

Dinoflagellates

Question 14

Which of the following statements about viruses is correct?

Accepted Answer

Viruses are obligate intracellular parasites that require a host cell for replication.

Question 15

A patient is diagnosed with malaria. Which of the following statements about the malaria parasite is correct?

Accepted Answer

It is a protozoan transmitted by mosquitoes, with humans as the intermediate host.

Question 16

Which of the following best explains why some viral infections can lead to cancer?

Accepted Answer

Retroviruses can insert their genome into the host DNA, potentially disrupting normal cell regulation.

Question 17

A scientist is studying a protein-only infectious agent that causes spongiform encephalopathies in mammals. What is this agent called, and how does it cause disease?

Accepted Answer

Prion; by inducing misfolding of normal proteins in the brain

Question 18

Which of the following best describes the difference between the lytic and lysogenic cycles of bacteriophage replication?

Accepted Answer

In the lysogenic cycle, the phage DNA integrates into the host genome and can remain dormant before entering the lytic cycle.

Question 19

A researcher is using site-directed mutagenesis to alter a gene in a bacterial genome. What is the primary purpose of this technique?

Accepted Answer

To create specific, targeted changes in a gene sequence

Question 20

Which of the following is a real-world concern associated with the use of genetically modified organisms (GMOs) in biotechnology?

Accepted Answer

There may be unpredictable effects on ecosystems and unresolved ethical issues.

Microbial Genetics, Biotechnology, Classification, and Viruses: Exam 2 Study Guide

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