Question 1

Which of the following bacteria is responsible for causing Rocky Mountain spotted fever, and what is its primary mode of transmission?

Accepted Answer

Rickettsia rickettsii; transmitted by insect and tick bites

Question 2

A plant develops a tumor-like growth at the junction of the root and stem, as shown in the second image. Which bacterium is most likely responsible, and what is the mechanism?

Accepted Answer

Agrobacterium tumefaciens; inserts a plasmid into plant cells

Question 3

Which of the following best describes the metabolic characteristics of the Pseudomonadota (formerly Proteobacteria)?

Accepted Answer

Gram-negative, chemoheterotrophic, metabolically diverse

Question 4

A patient presents with a severe cough and is diagnosed with whooping cough. Which bacterium is responsible, and what is a distinguishing feature?

Accepted Answer

Bordetella pertussis; nonmotile rod

Question 5

Which bacterium is commonly used as an indicator of fecal contamination in water and can also cause urinary tract infections?

Accepted Answer

Escherichia coli

Question 6

A hospital patient develops a red-pigmented infection on a catheter. Which bacterium is most likely responsible?

Accepted Answer

Serratia marcescens

Question 7

Which of the following bacteria is transmitted by fleas and is responsible for causing plague?

Accepted Answer

Yersinia pestis

Question 8

Which bacterium is associated with peptic ulcers and stomach cancer, and what is a key feature of its motility?

Accepted Answer

Helicobacter pylori; multiple flagella

Question 9

Which group of bacteria is known for carrying out oxygenic photosynthesis and played a major role in increasing atmospheric oxygen on early Earth?

Accepted Answer

Cyanobacteria

Question 10

A patient is diagnosed with syphilis. Which structure is responsible for the unique motility of the causative bacterium, as shown in the seventh image?

Accepted Answer

Axial filaments

Question 11

Which bacterium is an obligate intracellular parasite, forms an elementary body as part of its life cycle, and causes trachoma?

Accepted Answer

Chlamydia trachomatis

Question 12

Which genus of bacteria is endospore-forming, obligate anaerobic, and includes species that cause tetanus and botulism?

Accepted Answer

Clostridium

Question 13

A foodborne outbreak is traced to a bacterium that contaminates dairy products and can grow at refrigeration temperatures. Which bacterium is most likely responsible?

Accepted Answer

Listeria monocytogenes

Question 14

Which bacterium is pleomorphic, lacks a cell wall, and is a common cause of mild pneumonia?

Accepted Answer

Mycoplasma pneumoniae

Question 15

Which genus is known for producing many antibiotics and is commonly isolated from soil?

Accepted Answer

Streptomyces

Question 16

Which of the following equations best represents the oxygenic photosynthesis carried out by cyanobacteria?

Accepted Answer

$$2H_2O + CO_2$ \xrightarrow{light} CH_2O + H_2O + O_2$

Question 17

Which group of Archaea is characterized by the ability to grow in environments with a pH approaching 0?

Accepted Answer

Acidophiles

Question 18

A patient develops a wound infection with clusters of Gram-positive cocci that are resistant to antibiotics and produce an enterotoxin. Which bacterium is most likely responsible?

Accepted Answer

Staphylococcus aureus

Question 19

Which bacterium is known for surviving phagocytosis and causing brucellosis in mammals?

Accepted Answer

Brucella

Question 20

Which of the following best describes the role of Pelagibacter in the environment?

Accepted Answer

It is one of the most abundant microorganisms in oceans and plays a key role in the carbon cycle.

(Chapter 11) Classification and Diversity of Prokaryotes: Domains Bacteria and Archaea

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