OpenStax Microbiology Test Bank

Correct Answer: A

Rationale: The correct answer is A: Helicobacter pylori. Rationale: 1. Gram-negative spiral-shaped microorganisms match the morphology of Helicobacter pylori. 2. Positive urease activity is a characteristic feature of Helicjsonacter pylori. 3. Helicobacter pylori is specifically associated with gastric ulcers and is a common pathogen in the gastrointestinal tract. Summary: Choice B, Campilobacter jejuni, is a gram-negative curved bacterium but is not typically associated with gastric ulcers or urease activity. Choice C, Treponema pallidum, is a spirochete bacterium causing syphilis, which is not related to gastric ulcers. Choice D, Spirilla minor, is a generic term for spiral-shaped bacteria and is not a specific pathogen associated with gastric ulcers or urease activity.

Correct Answer: D

Rationale: The correct answer is D because the rubella virus has icosahedral symmetry, meaning it has a spherical shape with 20 equilateral triangular faces. This symmetry is common in many viruses and allows for efficient packaging of genetic material. Choice A is incorrect because the rubella virus does have glycoprotein spikes on its surface. These spikes help the virus attach to host cells. Choice B is incorrect because the rubella virus does have an envelope derived from the host cell membrane. This envelope plays a role in viral entry into host cells. Choice C is incorrect because the rubella virus is an ssRNA virus, not ssDNA. Its genetic material is single-stranded RNA, not DNA. In summary, the rubella virus has icosahedral symmetry and possesses glycoprotein spikes, an envelope, and ssRNA genetic material, making choices A, B, and C incorrect.

Correct Answer: C

Rationale: The correct answer is C: phialospores. Phialospores are conidiospores that bud off from a vase-shaped spore-bearing cell called a phialide. This structure is characteristic of fungi in the genus Penicillium. Arthrospores (A) are formed by the fragmentation of hyphae, porospores (B) are not a recognized term in mycology, and blastospores (D) are produced by budding from yeast cells. Therefore, C is the correct choice based on the specific description provided in the question.

Correct Answer: D

Rationale: The correct answer is D: PCR. PCR (Polymerase Chain Reaction) is the most suitable method for detecting genitourinary chlamydiosis due to its high sensitivity and specificity in detecting the genetic material of Chlamydia trachomatis. PCR can detect even low levels of the pathogen, providing accurate results. A: Cultural diagnostic is not as sensitive as PCR and may take longer to produce results. B: ELISA detects antibodies, which may not be present in early stages of infection, leading to false-negative results. C: CFT (Complement Fixation Test) is an older method with lower sensitivity compared to PCR for detecting chlamydiosis.

Correct Answer: A

Rationale: Rationale: 1. Thin, pale pink microorganisms with spiral coils suggest Treponema pallidum, the causative agent of syphilis. 2. Staining with Romanovsky-Giemsa method highlights the characteristic morphology of T. pallidum. 3. Syphilis presents with various stages and symptoms, correlating with the lymph node involvement. 4. Leptospirosis is caused by Leptospira interrogans, presenting with different clinical features. 5. Relapsing fever is caused by Borrelia species, which do not match the description. 6. Trypanosomiasis is caused by Trypanosoma species, which have distinct morphology and staining properties.