ATI RN
microbiology chapter 10 test bank Questions
Question 1 of 5
In a compound light microscope the lens closest to the eye is the __________ lens.
Correct Answer: A
Rationale: The correct answer is A: ocular lens. The ocular lens is the lens closest to the eye in a compound light microscope. This lens is responsible for magnifying the image produced by the objective lens. It typically has a magnification power of 10x. The objective lens, choice B, is positioned closer to the specimen and provides the primary magnification of the image. The condenser, choice C, is located beneath the stage and helps focus light onto the specimen. The stage, choice D, is where the specimen is placed for observation. Therefore, the ocular lens is the correct choice as it is the lens closest to the eye and responsible for further magnifying the image.
Question 2 of 5
A man is suffering from diarrhea. In summer he spent his vacation in the south at the sea coast. Bacteria with the following properties were detected in his feces: gram-negative curved mobile monotrichous bacilli that do not produce spores or capsules. They are undemanding to nutrient medium but require alkaline reaction (Ñ€H 8.5-9.5). Described are the agents of the following enteric infection:
Correct Answer: A
Rationale: Step-by-step rationale for why the correct answer is A (Cholera): 1. Gram-negative curved mobile monotrichous bacilli: Vibrio cholerae, the causative agent of cholera, fits this description. 2. Do not produce spores or capsules: Vibrio cholerae does not produce spores or capsules. 3. Require alkaline reaction (pH 8.5-9.5): Vibrio cholerae thrives in alkaline environments. 4. Enteric infection: Cholera is a classic example of an enteric infection transmitted through contaminated food or water. Summary of why other choices are incorrect: B: Shigellosis is caused by Shigella species, which are gram-negative, but they are not curved bacilli and do not require an alkaline pH. C: Typhoid fever is caused by Salmonella Typhi, which are gram-negative but are not curved bacilli and do not require an alkaline pH.
Question 3 of 5
The function of catalase in bacteria is to:
Correct Answer: A
Rationale: The correct answer is A: decompose hydrogen peroxide. Catalase is an enzyme that breaks down hydrogen peroxide into water and oxygen. This is important in bacteria to protect them from the harmful effects of hydrogen peroxide, a byproduct of metabolism. Choice B is incorrect as peptidoglycan synthesis is not the function of catalase. Choice C is incorrect as oxidative phosphorylation is a metabolic process unrelated to catalase function. Choice D is incorrect as endotoxin production is not a role of catalase.
Question 4 of 5
Method for rapid diagnosis of some viral infections is
Correct Answer: D
Rationale: The correct answer is D because utilizing all three methods—immunofluorescence, viral neutralization reaction, and electron microscopy—provides a comprehensive and rapid diagnosis of various viral infections. Immunofluorescence detects viral antigens directly, viral neutralization reaction demonstrates the presence of specific antibodies, and electron microscopy visualizes viral particles. This combination ensures accurate and quick identification of different viruses. Choices A, B, and C alone may not cover all aspects of viral diagnosis, making them less effective compared to the comprehensive approach of using all three methods.
Question 5 of 5
Which is not part of the normal skin microflora
Correct Answer: B
Rationale: The correct answer is B: serratia spp. This is because serratia spp. are not typically found in the normal skin microflora. Normal skin microflora primarily consist of bacteria such as diphtheroids, alpha-hemolytic streptococci, and epidermidis. Serratia spp. are more commonly associated with healthcare-associated infections rather than being a part of the skin's natural bacterial flora. Therefore, choice B is the correct answer. Choices A, C, and D are incorrect as they are commonly found in the normal skin microflora.