foundations in microbiology test bank

Correct Answer: A

Rationale: The correct answer is A because adaptive immunity is not mainly observed in the skin and mucous membranes. Adaptive immunity is a systemic response that involves specific immune cells and antibodies targeting specific pathogens. It develops immune memory (B), meaning it can recognize and respond faster upon re-exposure to the same pathogen. Adaptive immunity also has specificity (C), as it can target specific antigens. Lastly, adaptive immunity is not evolutionarily newer in comparison to innate immunity (D), as both systems have co-evolved to provide comprehensive protection against pathogens.

Correct Answer: D

Rationale: The correct answer is D because smallpox vaccination provides long-lasting immunity, often for a lifetime. Revaccination is not necessary as the initial vaccine confers sufficient protection. Choice A is incorrect because yearly revaccination is unnecessary and excessive. Choice B and C are also incorrect as there is no need for revaccination every second or third year. The key is to understand that smallpox vaccination typically provides lifelong immunity, making ongoing revaccination unnecessary.

Correct Answer: C

Rationale: The correct answer is C (coli index of 250 and coli titer of 4). The coli index is calculated by multiplying the number of colonies by the reciprocal of the volume filtered, which gives 2 colonies x (1/0.5 L) = 4. The coli titer is obtained by dividing the volume filtered by the number of colonies, which gives 0.5 L / 2 colonies = 0.25 L or 250 ml. This indicates the concentration of coliform bacteria in the water sample. Choice A (4 and 250) is incorrect because it has the correct coli index but the values are reversed for coli index and coli titer. Choice B (2 and 500) is incorrect as it provides the correct coli titer value but the values are reversed for coli index and coli titer. Choice D (500 and 2) is incorrect because it reverses the values for both coli index and coli titer.

Correct Answer: A

Rationale: Rationale for Correct Answer A (Diphtheria): 1. Thin yellow bacilli with dark brown grains on ends suggest Corynebacterium diphtheriae, characteristic of diphtheria. 2. Roman numeral five shape is typical of diphtheria bacilli. 3. Diphtheria causes sore throat and can spread in boarding schools. 4. Neisser staining method is used for diphtheria bacilli. Summary of Incorrect Choices: B: Scarlet fever is caused by Streptococcus pyogenes and presents with rash, not yellow bacilli. C: Listeriosis is caused by Listeria monocytogenes, not consistent with the described findings. D: Tonsillitis can be caused by various bacteria or viruses, but the specific characteristics described do not match.

Correct Answer: D

Rationale: The correct answer is D: Kinyoun stain. This stain is the most widely used differential stain in hematology labs because it is specifically designed for acid-fast bacteria like Mycobacterium tuberculosis. It differentiates these bacteria from others based on their cell wall composition. Carbolfuchsin stain (A) is used for acid-fast bacteria in microbiology. Wright's stain (B) is used for blood cell morphology. Ziehl-Neelsen stain (C) is also used for acid-fast bacteria but is less commonly used compared to Kinyoun stain in hematology labs.