Question 1

Which phylum contains the largest number of cultured bacterial species, and what is a key feature of its metabolic diversity?

Accepted Answer

Proteobacteria; extensive horizontal gene flow shapes metabolic diversity

Question 2

The 2021 renaming of Proteobacteria resulted in which new phylum name?

Accepted Answer

Pseudomonadota

Question 3

A bacterium is described as 'Candidatus.' What does this designation indicate?

Accepted Answer

It is a well-characterized bacterium that is not yet culturable or not in pure culture.

Question 4

Which class of Proteobacteria contains nearly 50% of all characterized species in the phylum and includes many medically relevant genera?

Accepted Answer

Gamma-Proteobacteria

Question 5

Which metabolic test distinguishes enteric bacteria from many other Gram-negative bacteria?

Accepted Answer

Catalase (+) and Oxidase (–)

Question 6

Mixed-acid fermentation in enteric bacteria produces which combination of products?

Accepted Answer

Acetic, lactic, and succinic acids, ethanol, and equal amounts of CO$$_2$$ and H$$_2$$

Question 7

Which genus is associated with 2,3-butanediol fermentation as a main metabolic pathway?

Accepted Answer

Enterobacter

Question 8

A patient presents with pneumonia and is found to have a Gram-negative, non-sporulating rod that is catalase (+) and oxidase (–). Which genus is most likely responsible?

Accepted Answer

Klebsiella

Question 9

Which genus of Alpha-Proteobacteria is known for causing plant crown gall disease and is used in genetic modification of plants?

Accepted Answer

Agrobacterium

Question 10

Which medically relevant genus of Beta-Proteobacteria is responsible for whooping cough?

Accepted Answer

Bordetella

Question 11

Which class of Proteobacteria includes predatory bacteria such as Bdellovibrio?

Accepted Answer

Delta-Proteobacteria

Question 12

Campylobacter jejuni, a major cause of foodborne illness, belongs to which class of Proteobacteria?

Accepted Answer

Epsilon-Proteobacteria

Question 13

Which genus is the most abundant bacterial species on Earth's ocean surface?

Accepted Answer

Pelagibacter

Question 14

Which genus of Gamma-Proteobacteria is associated with nosocomial infections and is normally part of the human gut flora?

Accepted Answer

Enterobacter

Question 15

Which genus of Alpha-Proteobacteria is an intracellular parasite of arthropods and nematodes, infecting up to 75% of all insects?

Accepted Answer

Wolbachia

Question 16

Which genus is responsible for epidemic Typhus and wiped out a third of Napoleon’s army?

Accepted Answer

Rickettsia

Question 17

Which order of Gamma-Proteobacteria includes genera such as Escherichia, Salmonella, and Shigella?

Accepted Answer

Enterobacteriales

Question 18

Which genus of Gamma-Proteobacteria is known for producing Shiga toxin and causing dysentery?

Accepted Answer

Shigella

Question 19

Which genus of Gamma-Proteobacteria is associated with cholera and death by dehydration due to toxin production?

Accepted Answer

Vibrio

Question 20

Which class of Proteobacteria includes bacteria that oxidize H$$_2S $$and fix CO$$_2$$ via the reverse TCA cycle?

Accepted Answer

Epsilon-Proteobacteria

Phylogenetic and Metabolic Diversity of Bacteria: Focus on Proteobacteria and Major Bacterial Phyla

Study Guide - Practice Questions

Study Guide - Flashcards