Acute hemorrhagic cystitis may be due to:

Correct Answer: C

Rationale: Rationale for choice C (Adenovirus) being correct: 1. Adenovirus is a common cause of acute hemorrhagic cystitis. 2. Adenovirus infects the bladder epithelium, leading to inflammation and bleeding. 3. Symptoms include hematuria and bladder pain. 4. Diagnosis is confirmed through viral culture or PCR testing. Summary of why other choices are incorrect: A: Parvovirus B19 - More commonly associated with erythema infectiosum (fifth disease) and aplastic anemia. B: CMV - Known to cause congenital infections, mononucleosis, and retinitis, not typically associated with hemorrhagic cystitis. D: Herpesvirus type 2 - Commonly causes genital herpes, but not typically associated with acute hemorrhagic cystitis.

Correct Answer: A

Rationale: The correct answer is A: Late congenital syphilis. The symptoms described align with late congenital syphilis, which includes saddle nose, high-arched palate, natiform skull, peg-shaped incisors, and notched cutting edge. Lymph nodes not being affected is also consistent with late congenital syphilis. Early congenital syphilis (B) typically presents with more severe symptoms at birth or shortly after. Tertiary syphilis (C) usually occurs years after initial infection and presents with different symptoms. Fluorosis (D) is caused by excessive fluoride intake and does not match the symptoms described.

Correct Answer: B

Rationale: The correct answer is B: Fimbriae. Fimbriae are hair-like appendages found on the surface of bacteria that enable attachment to host cells. This attachment is crucial for establishing infection. Flagella (A) are used for movement, not attachment. Capsules (C) provide protection and help evade the host immune system, but do not directly facilitate attachment. Endospores (D) are dormant structures for survival, not for attachment to host cells. Fimbriae specifically aid in adherence to host cells, making them the correct choice in this context.

Correct Answer: B

Rationale: Step-by-step rationale for choice B being correct: 1. The conclusion should be based on evidence or observations. 2. "Doubtful" suggests uncertainty, indicating lack of definitive safety. 3. Choice A is too absolute without considering potential risks. 4. Choice C uses extreme language without proper evidence. 5. Choice D is overly definitive without considering varying levels of contamination. Therefore, choice B is the most reasonable conclusion.

Correct Answer: B

Rationale: The correct answer is B: Rhodophyta. Rhodophyta is the phylum of red algae, which are known to contain agar in their cell walls. Agar is a gelatinous substance derived from these algae. Chrysophyta (A), Chlorophyta (C), and Phaeophyta (D) do not typically contain agar in their cell walls. Chrysophyta includes diatoms, Chlorophyta includes green algae, and Phaeophyta includes brown algae, none of which are known for agar production. Therefore, Rhodophyta is the correct choice based on the presence of agar in their cell walls.