microbiology a systems approach test bank

Correct Answer: C

Rationale: Step 1: Actinomycotic granules are colonies of actinomycetes located in purulent secretions. Step 2: Actinomycosis is a disease caused by actinomycetes forming these granules. Step 3: Actinomycotic granules are typically found in tissue exudates or pus. Step 4: Therefore, choice C is correct as it accurately describes actinomycotic granules. Summary: Choice A is incorrect because actinomycotic granules are not a form of actinomycosis itself, but a characteristic of the disease. Choice B is incorrect as actinomycotic granules are not an additional outer membrane but rather colonies of actinomycetes. Choice D is incorrect as actinomycotic granules are not intracellular inclusions but extracellular colonies found in purulent secretions.

Correct Answer: A

Rationale: The correct answer is A: Staphylococcus epidermidis. The presence of Gram-positive cocci in clusters, along with being catalase-positive and coagulase-negative, is indicative of Staphylococcus species. Staphylococcus epidermidis is commonly found on the skin, making it likely to cause wound infections. Summary: B: Staphylococcus aureus is catalase-positive and coagulase-positive. C: Streptococcus pyogenes is catalase-negative. D: Enterococcus faecalis is catalase-negative.

Correct Answer: C

Rationale: The correct answer is C: adhesion to surfaces and conjugation. Pili are hair-like structures on the surface of bacteria that help them adhere to surfaces and facilitate the transfer of genetic material during conjugation. This is essential for bacterial survival and reproduction. Choice A is incorrect because protection from desiccation is typically associated with other structures like capsules. Choice B is incorrect as motility in bacteria is usually facilitated by flagella. Choice D is incorrect as spore formation involves the formation of specialized structures, not pili.

Correct Answer: B

Rationale: The correct answer is B because retroviruses, including those in the Family Retroviridae, have a capsid consisting of two copies of single-stranded RNA (ssRNA). This is a defining characteristic of retroviruses, which use reverse transcriptase to convert their ssRNA into DNA. This DNA is then integrated into the host cell's genome. Choices A, C, and D are incorrect because Family Retroviridae viruses are not helical non-enveloped viruses (C), they are not helical enveloped viruses (A), and they do not have a complex type of symmetry (D).

Correct Answer: A

Rationale: The correct answer is A: Amebiasis. Amebiasis is caused by the parasite Entamoeba histolytica, presenting with symptoms like acute abdominal pain, bloody diarrhea with mucus, and inconstant shape organisms seen in fecal smear. The presence of erythrocytes supports the diagnosis due to the parasite's ability to invade intestinal mucosa causing bleeding. Choice B (Lambliasis) presents with different symptoms like steatorrhea and fatigue. Choice C (Schistosomiasis) is mainly associated with liver and urinary symptoms. Choice D (Intestinal trichomoniasis) commonly presents with watery diarrhea and does not typically cause bloody stools. Therefore, based on the patient's symptoms and fecal smear findings, Amebiasis is the most likely diagnosis.