Question 1

Which of the following statements best describes the main difference between Bacteria and Archaea?

Accepted Answer

Bacteria and Archaea are classified in different domains based on genetic sequence comparisons.

Question 2

A patient presents with severe diarrhea, vomiting, and dehydration after drinking contaminated water. Which Gram-negative bacterium is most likely responsible, and what is its primary mode of transmission?

Accepted Answer

Vibrio cholerae; contaminated water and food

Question 3

Thiomargarita namibiensis uses hydrogen sulfide ($$\mathrm{H_2S}) to $$generate organic molecules from carbon dioxide ($$\mathrm{CO_2$}). $$What type of metabolism does this represent?

Accepted Answer

Chemoautotrophy

Question 4

Which process is performed by Rhizobium species in the root nodules of legumes, and why is it ecologically significant?

Accepted Answer

Nitrogen fixation; it converts atmospheric $$\mathrm{N_2$}$$ into ammonia usable by plants

Question 5

A woman with no symptoms is diagnosed with pelvic inflammatory disease and infertility. Which Gram-negative coccus is most likely responsible, and what is a major public health concern regarding its treatment?

Accepted Answer

Neisseria gonorrhoeae; development of penicillin-resistant strains

Question 6

Which of the following is true about cyanobacteria?

Accepted Answer

They are Gram-negative bacteria and the only prokaryotes with plantlike, oxygen-generating photosynthesis.

Question 7

A sexually transmitted infection is found to be caused by a Gram-negative bacterium that lives inside eukaryotic host cells and is often symptomless. Which organism is most likely responsible?

Accepted Answer

Chlamydia trachomatis

Question 8

Which of the following best explains why frequent testing for Chlamydia trachomatis is important in sexually active individuals?

Accepted Answer

The infection is often symptomless, but can cause pelvic inflammatory disease and infertility if not detected early.

Question 9

A patient develops a rash followed by flu-like symptoms after a tick bite. Which Gram-negative, helical bacterium is most likely responsible?

Accepted Answer

Borrelia species

Question 10

Which of the following is a characteristic of Helicobacter pylori that enables it to colonize the stomach and cause ulcers?

Accepted Answer

It is a Gram-negative curved bacillus with multiple flagella.

Question 11

Which genus of Gram-positive bacteria is a major source of antibiotics such as streptomycin and is commonly found in soil?

Accepted Answer

Streptomyces

Question 12

A foodborne illness is traced to an anaerobic, spore-forming bacterium that produces a neurotoxin causing muscle paralysis. Which organism is responsible, and what is the best method to prevent this illness?

Accepted Answer

Clostridium botulinum; proper canning and food preservation techniques

Question 13

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

Accepted Answer

They are common soil bacteria that decompose organic matter.

Question 14

Which of the following equations best represents the process of nitrogen fixation performed by Rhizobium species?

Accepted Answer

$$\mathrm{N_2$ + 8H^+ + 8e^- + 16ATP \rightarrow 2NH_3 + H_2$ + 16ADP + 16P_i}$$

Question 15

Which of the following is a distinguishing feature of spirochetes such as Treponema pallidum?

Accepted Answer

They are Gram-negative, helical bacteria with axial filaments for movement.

Question 16

A patient is diagnosed with tetanus after a puncture wound. Which bacterium is responsible, and what is the mechanism of disease?

Accepted Answer

Clostridium tetani; production of exotoxins causing uncontrolled muscle spasms

Question 17

Which of the following best explains why Clostridium species can persist in the environment for long periods?

Accepted Answer

They form endospores that are resistant to harsh conditions.

Question 18

Which of the following scenarios best illustrates endosymbiosis?

Accepted Answer

Rhizobium bacteria living within root nodules of legumes, providing nitrogen to the plant.

Question 19

Which of the following is a real-world consequence of antibiotic resistance in Neisseria gonorrhoeae?

Accepted Answer

Increased risk of untreatable infections and complications such as infertility.

Chapter 11: The Prokaryotes – Domains Bacteria and Archaea

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