Microbiology Chapter 14 Test Bank

Correct Answer: D

Rationale: The correct answer is D: Rifampicin. Rifampicin is a first-line antibiotic for treating pulmonary tuberculosis due to its high efficacy against Mycobacterium tuberculosis. It works by inhibiting bacterial RNA synthesis. Furasolidone (A) is not commonly used for tuberculosis, Bactrim (B) is not a first-line drug for tuberculosis, and Streptocide (C) is not as effective as Rifampicin.

Correct Answer: B

Rationale: The correct answer is B: Azotobacter species. Azotobacter are known for their ability to fix nitrogen through the process of nitrogen fixation, converting atmospheric nitrogen into a form that plants can use. Bacillus cereus is not known for nitrogen fixation. Clostridium botulinum is a bacterium that causes botulism and does not fix nitrogen. Escherichia coli is a common gut bacterium but does not have the ability to fix nitrogen. Thus, Azotobacter species is the correct choice based on its unique ability to fix nitrogen.

Correct Answer: A

Rationale: The correct answer is A: Treponema pallidum. This bacterium is responsible for causing syphilis due to its unique spiral shape and ability to penetrate intact mucous membranes. It is transmitted through sexual contact or from mother to child during pregnancy. Neisseria gonorrhoeae causes gonorrhea, Chlamydia trachomatis causes chlamydia, and Escherichia coli is a common bacterium found in the gut and not associated with syphilis. Treponema pallidum's specific characteristics and mode of transmission distinguish it from the other choices, making it the correct answer.

Correct Answer: B

Rationale: The correct answer is B because a viral capsid is a protein coat that surrounds and protects the viral nucleic acid (DNA or RNA). It helps in the attachment of the virus to host cells and protects the genetic material during transmission. Choice A is incorrect because a viral capsid is composed of proteins, not an envelope. Choice C is incorrect because not all viruses have an outer membrane. Choice D is incorrect because a viral capsid is primarily made up of proteins, not lipids.

Correct Answer: A

Rationale: The correct answer is A: Lamblia. The description matches the characteristics of Giardia lamblia - a protozoan parasite that causes giardiasis. The piriform bodies, 4 pairs of filaments, and two symmetrically located nuclei are specific to Giardia lamblia. It is important to differentiate it from the other choices. Dysentery ameba (choice B) typically has a single nucleus and lacks the specific characteristics described. Trichomonas (choice C) is a flagellated protozoan with different morphology and does not match the given description. Intestinal ameba (choice D) such as Entamoeba histolytica usually has a single nucleus and different body shape compared to the described organism.