Nokea
Mesophylic bacteria are with temperature optimum:
- A. 25-37 °C
- B. 55-65 °C
- C. 15-18 °C
- D. 38-45 °C
Correct Answer: A
Rationale: The correct answer is A (25-37 °C) because mesophilic bacteria thrive best at moderate temperatures typical of most environments, making 25-37 °C their optimum range. This range allows for optimal enzyme activity and growth. Choice B (55-65 °C) is incorrect as it is more suitable for thermophilic bacteria. Choice C (15-18 °C) is too low for mesophiles to thrive efficiently. Choice D (38-45 °C) is too high and is more suitable for thermophiles. Ultimately, the correct answer aligns with the typical temperature range where mesophilic bacteria are most active and abundant.
You may also like to solve these questions
The symmetry of nucleocapsid of poxviruses is:
- A. Complex
- B. Isohedral
- C. Helical
- D. All of the above
Correct Answer: A
Rationale: The correct answer is A: Complex. Poxviruses have a complex nucleocapsid symmetry due to their unique structure with multiple layers of proteins and genetic material. Isohedral symmetry (B) refers to a regular polyhedron shape, which is not characteristic of poxviruses. Helical symmetry (C) is found in viruses like tobacco mosaic virus, not poxviruses. "All of the above" (D) is incorrect because poxviruses do not exhibit isohedral or helical symmetry.
Which of the following is a disease caused by a protozoan?
- A. Cat scratch disease
- B. Toxoplasmosis
- C. Relapsing fever
- D. Plague
Correct Answer: B
Rationale: The correct answer is B: Toxoplasmosis. Toxoplasmosis is caused by the protozoan Toxoplasma gondii. The rationale for this is that protozoa are single-celled organisms that can cause diseases in humans. Cat scratch disease (A) is caused by a bacterium, Bartonella henselae. Relapsing fever (C) is caused by the bacterium Borrelia recurrentis. Plague (D) is caused by the bacterium Yersinia pestis. Therefore, the only choice caused by a protozoan is toxoplasmosis, making it the correct answer.
Differentiating media are:
- A. Lowenstein-Jensen and Petraniani
- B. Apoholate-citrate aga and Brilliant-green phenol-red Lactose Agar
- C. Endo, Gassner and Levin
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C because Endo, Gassner, and Levin are all examples of differential media used in microbiology. These media contain specific components that allow for the differentiation of different types of microorganisms based on their metabolic characteristics or biochemical reactions. Lowenstein-Jensen and Petraniani (choice A) are selective media for mycobacteria, not differential. Apoholate-citrate agar and Brilliant-green phenol-red Lactose agar (choice B) are selective media for Salmonella and E. coli, respectively, not differential. Therefore, the correct choice is C as it includes examples of differential media commonly used for microbial identification.
A 45-year-old patient has foul-smelling diarrhea. Stool examination revealed large ciliated protozoa with a kidney-shaped macronucleus. What is the causative agent?
- A. Balantidium coli
- B. Entamoeba histolytica
- C. Giardia lamblia
- D. Trichomonas hominis
Correct Answer: A
Rationale: The correct answer is A: Balantidium coli. This large ciliated protozoa with a kidney-shaped macronucleus is characteristic of Balantidium coli, an intestinal parasite known to cause foul-smelling diarrhea in humans. Balantidium coli is the only option among the choices that fits this specific description. Entamoeba histolytica causes amoebic dysentery, Giardia lamblia causes giardiasis, and Trichomonas hominis is a non-pathogenic protozoa found in the intestinal tract. Therefore, based on the morphology described in the question, Balantidium coli is the correct causative agent.
Agents associated with human disease but generally not a serious health risk are classified in which of the following risk groups?
- A. RG1
- B. RG2
- C. RG3
- D. RG4
Correct Answer: B
Rationale: The correct answer is B: RG2. RG2 is appropriate for agents associated with human disease that pose a moderate health risk. These agents may cause disease of varying severity, but generally do not result in serious health consequences. Other choices are incorrect because: A: RG1 is for agents not associated with disease in healthy adults, C: RG3 is for agents associated with serious or lethal human disease, and D: RG4 is for agents that pose a high risk of life-threatening disease and for which there are no treatments.