Question 1

Which of the following best explains why 16S rRNA gene sequencing is widely used in bacterial taxonomy and phylogeny?

Accepted Answer

Because its sequence is highly conserved among bacteria, but contains variable regions that allow for differentiation between species.

Question 2

A farmer is interested in using bacteria to improve soil fertility by increasing nitrogen content. Which group of bacteria would be most beneficial for this purpose?

Accepted Answer

Azospirillum (a type of Proteobacteria)

Question 3

Which of the following statements about Wolbachia is correct?

Accepted Answer

It infects many species of insects and can alter their reproduction to increase its own spread.

Question 4

A patient presents with severe watery diarrhea after eating undercooked shellfish. Which genus of bacteria is most likely responsible?

Accepted Answer

Vibrio

Question 5

Which of the following bacteria is most commonly associated with the development of peptic ulcers and stomach cancer?

Accepted Answer

Helicobacter pylori

Question 6

A hospital outbreak of pneumonia is traced to contaminated catheters. Which Gram-negative bacterium is most likely responsible?

Accepted Answer

Klebsiella pneumoniae

Question 7

Which of the following is a distinguishing feature of Mycobacterium species?

Accepted Answer

They have a cell wall rich in mycolic acids, making them acid-fast.

Question 8

Which of the following best describes the role of Streptomyces in medicine?

Accepted Answer

They produce most of our commercially available antibiotics.

Question 9

A child is diagnosed with whooping cough. Which bacterium is responsible, and how can the disease be prevented?

Accepted Answer

Bordetella pertussis; prevented by Tdap and DTaP vaccines

Question 10

Which of the following bacteria is most likely to cause foodborne illness from undercooked poultry and is the most common bacterial cause of diarrheal illness in the United States?

Accepted Answer

Campylobacter jejuni

Question 11

Which of the following best explains why Enterobacteriaceae are able to survive in both oxygen-rich and oxygen-poor environments?

Accepted Answer

They are facultative anaerobes.

Question 12

A patient develops a black, swollen lymph node after being bitten by a flea that fed on a rat. Which bacterium is most likely responsible for this disease?

Accepted Answer

Yersinia pestis

Question 13

Which of the following is a key feature of cyanobacteria that distinguishes them from other bacteria?

Accepted Answer

They perform oxygenic photosynthesis and produce oxygen.

Question 14

Which of the following bacteria is most likely to cause meningitis and is commonly found in the genus Neisseria?

Accepted Answer

N. meningitidis

Question 15

A patient presents with a severe sore throat and a grayish membrane covering the throat. Which bacterium is most likely responsible?

Accepted Answer

Corynebacterium diphtheriae

Question 16

Which of the following best describes the difference between high G+C and low G+C Gram-positive bacteria?

Accepted Answer

High G+C bacteria have a higher percentage of guanine and cytosine in their DNA, such as Streptomyces and Mycobacterium.

Question 17

Which of the following bacteria is most likely to cause listeriosis, especially in pregnant women and immunocompromised individuals, after consumption of contaminated soft cheese?

Accepted Answer

Listeria monocytogenes

Question 18

A patient develops a spiral-shaped, motile bacterial infection after being bitten by a tick. The patient later develops a bullseye rash. Which bacterium is most likely responsible?

Accepted Answer

Borrelia burgdorferi

Question 19

Which of the following is a common feature of bacteria in the genus Clostridium?

Accepted Answer

They are endospore-forming anaerobes that can cause diseases such as tetanus and botulism.

Question 20

A patient presents with a dental abscess that has progressed deep into the tissue, causing pus in the root canal. Which anaerobic bacterium is most likely responsible?

Accepted Answer

Fusobacterium

Microbiology Study Notes: Prokaryotes, Bacterial Classification, and Major Bacterial Groups

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