microbiology chapter 12 test bank

Correct Answer: B

Rationale: Bacillary dysentery is caused by the bacterium Shigella, hence it is also known as shigellosis. Shigella is the primary pathogen responsible for this infectious disease, leading to severe diarrhea with blood and mucus. Salmonellosis (A) is caused by Salmonella bacteria, not Shigella. Typhoid fever (C) is caused by Salmonella typhi, not Shigella. Campylobacteriosis (D) is caused by Campylobacter bacteria, not Shigella. Therefore, the correct answer is B because Shigella is the specific bacterium associated with bacillary dysentery.

Correct Answer: A

Rationale: The correct answer is A: Smooth S colonies. Bacteria with long O-specific chains are known as smooth strains, and when cultured on solid growth media, they form smooth colonies due to the presence of the O antigen. This gives them a glossy appearance. Rough R colonies (Choice B) lack O antigen and appear rough. Mucoid -M colonies (Choice C) are associated with capsules, not O-specific chains. H colonies (Choice D) are not relevant to the O-specific chains. Smooth S colonies are the characteristic phenotype of bacteria with long O-specific chains when cultured on solid media.

Correct Answer: C

Rationale: The correct answer is C: Obligate aerobes. These bacteria require oxygen for their survival and growth. They utilize oxygen in their metabolic processes and cannot survive in the absence of oxygen. Choice A, obligate anaerobes, cannot survive in the presence of oxygen. Choice B, facultative anaerobes, can switch between aerobic and anaerobic metabolism based on oxygen availability. Choice D, aerotolerant anaerobes, can tolerate the presence of oxygen but do not require it for their growth. Therefore, the most appropriate term for bacteria that require oxygen for survival is obligate aerobes.

Correct Answer: B

Rationale: The correct answer is B: halophiles. Halophiles are bacteria that thrive in high salt environments. They have adapted to survive and grow in areas with high salt concentrations. This preference for high salt levels is what distinguishes halophiles from other types of bacteria. A: Calciphiles are bacteria that prefer high levels of calcium. C: Osmophiles are bacteria that thrive in environments with high sugar concentrations. D: Mesophiles are bacteria that prefer moderate temperature ranges for growth. In summary, the correct term for bacteria that prefer high levels of salt in their growing environment is halophiles, making choices A, C, and D incorrect in this context.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Arenaviridae family includes viruses with a segmented genome. 2. Lassa virus has a segmented genome, placing it in the Arenaviridae family. 3. Crimean-Congo hemorrhagic fever virus belongs to the Nairoviridae family, not Arenaviridae. 4. Rabies virus belongs to the Rhabdoviridae family, not Arenaviridae. 5. Epstein-Barr virus belongs to the Herpesviridae family, not Arenaviridae. Summary: A: Lassa virus is correct because it has a segmented genome, characteristic of Arenaviridae. B, C, D: Crimean-Congo hemorrhagic fever virus, Rabies virus, and Epstein-Barr virus belong to different virus families, not Arenaviridae.