Nokea
The tool of choice to observe living microorganisms is the
- A. bright-field microscope
- B. phase-contrast microscope
- C. fluorescence microscope
- D. electron microscope
Correct Answer: B
Rationale: The correct answer is B: phase-contrast microscope. This type of microscope is ideal for observing living microorganisms because it enhances the contrast of transparent specimens without the need for staining or fixing, allowing for clear visualization of internal structures and movements. Bright-field microscopes (A) are suitable for observing fixed and stained specimens, not living organisms. Fluorescence microscopes (C) are used to detect specific cellular components tagged with fluorescent markers, not ideal for observing overall morphology. Electron microscopes (D) use electron beams and are best for viewing detailed structures at high magnification, but are not suitable for observing living organisms due to the need for vacuum conditions.
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Which of the following sites of the human body does not have a normal flora?
- A. Intestine
- B. Skin
- C. Vagina
- D. Blood
Correct Answer: D
Rationale: The correct answer is D: Blood. Normal flora refers to the microorganisms that naturally inhabit specific areas of the body. Blood is considered a sterile environment in healthy individuals, meaning it does not harbor any microorganisms under normal circumstances. In contrast, the intestine, skin, and vagina all have normal flora as they provide suitable environments for various microbial species to thrive. The presence of normal flora in these sites helps maintain a balance and protect against pathogenic invaders. Blood, being a vital and sterile fluid, is not meant to have any resident microbial populations.
Which of the following media is often used to grow Mycobacterium tuberculosis?
- A. Middlebrook’s medium
- B. Heart infusion broth
- C. MacConkey agar
- D. Middlebrook’s medium
Correct Answer: D
Rationale: The correct answer is D: Middlebrook's medium. This medium is specifically designed for the growth of Mycobacterium tuberculosis due to its low concentration of malachite green, which inhibits the growth of other bacteria but not Mycobacterium species. Middlebrook's medium also contains various nutrients that support the growth of Mycobacterium tuberculosis.
A: Middlebrook's medium is the correct answer, not incorrect.
B: Heart infusion broth is a general-purpose medium, not specific for Mycobacterium tuberculosis.
C: MacConkey agar is selective for gram-negative bacteria and would not support the growth of Mycobacterium tuberculosis.
In summary, Middlebrook's medium is the ideal choice for cultivating Mycobacterium tuberculosis due to its specific formulation that promotes the growth of this pathogen while inhibiting other bacteria.
Choose which one fo the following microorganisms is an example of obligate parasitism
- A. HIV
- B. E. Coli
- C. S. Epidermidis
- D. Pseudomonas aeruginosa
Correct Answer: A
Rationale: The correct answer is A: HIV. HIV is an example of obligate parasitism because it requires a host cell to replicate and survive. It cannot live independently outside of a host organism. In contrast, choices B, C, and D are not obligate parasites. E. Coli and S. Epidermidis are examples of commensal bacteria that can live in the host without causing harm. Pseudomonas aeruginosa can be both an opportunistic pathogen and a free-living organism, not strictly dependent on a host for survival.
Specify the microbiological characteristic of the air:
- A. Contaminated
- B. Within the permissible limits
- C. Almost pure
- D. Pure
Correct Answer: A
Rationale: The correct answer is A: Contaminated. The air is never completely free of microorganisms, so it is considered contaminated. Microorganisms are ubiquitous in the environment. Permissible limits (B) imply a specific standard, which is not relevant to the general microbiological characteristic of air. Almost pure (C) and pure (D) are not accurate as air always contains some level of microorganisms.
Which of the following viruses does not belong to family Paramyxoviridae:
- A. Measles virus
- B. Respiratory syncytial virus
- C. Mumps virus
- D. Rubella virus
Correct Answer: D
Rationale: The correct answer is D: Rubella virus. Rubella virus does not belong to the family Paramyxoviridae because it belongs to the Togaviridae family. The other choices, A (Measles virus), B (Respiratory syncytial virus), and C (Mumps virus) are all members of the Paramyxoviridae family. This classification is based on the genetic and structural characteristics of the viruses. Rubella virus is distinct in its genetic composition and replication cycle compared to the Paramyxoviridae family, making it the correct choice.