mcgraw hill microbiology test bank

Correct Answer: B

Rationale: The correct answer is B: Disinfection. Disinfection is not a method for food preservation but rather a process of destroying harmful microorganisms on surfaces. A: Pasteurization involves heating food to kill pathogens, preserving the food. C: Irradiation uses radiation to kill bacteria and parasites, extending shelf life. D: Ultrahigh-temperature pasteurization involves heating food at very high temperatures to extend shelf life. In summary, disinfection is not a method used to preserve food but rather to clean surfaces.

Correct Answer: C

Rationale: The correct answer is C: Plague. Yersinia pestis is a bacterium that causes plague, a serious infectious disease transmitted through infected fleas or direct contact with infected animals. Yersinia pestis does not cause Cholera (choice A) or AIDS (choice B). Choice D, None of the above, is incorrect as Yersinia pestis is indeed the causative agent of plague.

Correct Answer: D

Rationale: The correct answer is D: Positive strand RNA viruses. These viruses have RNA genomes that can be directly translated by host ribosomes without the need for transcription. In contrast, single-strand DNA and double-strand DNA viruses require transcription to generate mRNA for translation. Choice A is incorrect as there is a correct answer. Choice B and C are incorrect because both single-strand DNA and double-strand DNA viruses require transcription for mRNA synthesis.

Correct Answer: A

Rationale: The correct answer is A: Giardia lamblia. This protozoan matches the description of the causative agent because it has two nuclei, four flagella, and a ventral adhesive disc. Giardia lamblia is commonly found in the duodenum and causes giardiasis. The other choices can be eliminated because Leishmania donovani causes visceral leishmaniasis, not the described symptoms. Entamoeba coli is a non-pathogenic amoeba found in the large intestine. Trypanosoma gambiense causes African trypanosomiasis and is transmitted by the tsetse fly, not matching the described characteristics.

Correct Answer: C

Rationale: The correct answer is C: Macrolides or fluoroquinolones. Legionella pneumophila is a bacterium that causes Legionnaires' disease, a severe form of pneumonia. Macrolides (like azithromycin) and fluoroquinolones (like levofloxacin) are the recommended first-line treatments due to their ability to penetrate into lung tissues where Legionella infects. Penicillins and cephalosporins (choice A) are not effective against Legionella as it is intracellular and resistant to these antibiotics. Ethambutol and isoniazid (choice B) are used to treat tuberculosis, not Legionella infections. Second and third generation cephalosporins (choice D) are also not effective against Legionella. Therefore, the best choice for treating Legionella pneumophila infections is macrolides or fluoroquinolones.