microbiology chapter 12 test bank

Correct Answer: D

Rationale: The correct answer is D: All of the above. Hepatitis B infection can present with jaundice due to liver inflammation, elevated serum aminotransferase levels due to liver damage, and sometimes no symptoms in the acute phase. This comprehensive presentation covers the spectrum of possible clinical manifestations of hepatitis B infection. Choices A and B are correct as they are common manifestations of hepatitis B infection. Choice C is incorrect as hepatitis B infection can indeed present with symptoms, making option D the most appropriate choice.

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: A

Rationale: The presence of flagella in a bacterial cell represents the H-antigen. Flagella are protein structures on the cell surface that play a role in bacterial motility. The H-antigen refers to the flagellar antigen, which is involved in immune responses and bacterial identification. Option A is correct because flagella are specifically associated with the H-antigen. Summarily, choices B and C are incorrect because the O-antigen and K-antigen are associated with lipopolysaccharide and capsule antigens, respectively, not flagella. Option D is incorrect as well because the correct association is with the H-antigen.

Correct Answer: A

Rationale: The correct answer is A because growth factors are essential nutrients that bacteria cannot synthesize on their own and must obtain from the environment for their growth. Bacteria rely on these external factors for processes like cell division, metabolism, and survival. Choice B is incorrect because bacteria can only synthesize growth factors in limited amounts, not sufficient for their growth. Choice C is incorrect as bacterial cells do not store growth factors in granules. Choice D is incorrect because bacterial cells do not synthesize growth factors in large amounts.