Nokea
Which of the following bacteria are unable to synthesize ATP?
- A. Chlamydia
- B. Enterococci
- C. Rickettsia
- D. Staphylococci
Correct Answer: A
Rationale: The correct answer is A: Chlamydia. Chlamydia lacks the essential enzymes for ATP synthesis and relies on host cell ATP. Enterococci, Rickettsia, and Staphylococci possess the necessary enzymes for ATP synthesis through cellular respiration. Chlamydia's inability to synthesize ATP makes it dependent on the host cell for energy production, distinguishing it from the other bacteria listed.
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A centrifugate of urine sample obtained from patient with suspected renal tuberculosis was used to make a slide mount for microscopy. What method should be used to stain the slide and detect the causative agent?
- A. Zielh-Neelsen stain
- B. Loeffler stain
- C. Gram stain
- D. Aujeszky stain
Correct Answer: A
Rationale: The correct answer is A: Zielh-Neelsen stain. This stain is specifically used to detect acid-fast bacteria like Mycobacterium tuberculosis, the causative agent of renal tuberculosis. The staining process involves using carbol fuchsin to penetrate the mycolic acid layer of the bacterial cell wall, making it resistant to decolorization with acid-alcohol. This allows the red stained bacteria to be visualized under a microscope. Loeffler stain (B) is used for staining bacteria like diphtheria bacilli, Gram stain (C) is used for bacterial classification based on cell wall properties, and Aujeszky stain (D) is not a recognized staining method for detecting acid-fast bacteria.
Chlorine belongs to which of the following chemical groups?
- A. Halogens
- B. Heavy metals
- C. Phenols
- D. Alcohols
Correct Answer: A
Rationale: The correct answer is A: Halogens. Chlorine belongs to the halogens group because it is a nonmetal element in group 17 of the periodic table. Halogens are highly reactive elements that have 7 electrons in their outer shell, making them eager to gain an electron to achieve stability. Chlorine specifically is a diatomic molecule with the chemical symbol Cl and atomic number 17.
Option B: Heavy metals are elements with high atomic weights and densities, such as lead and mercury, which are not related to chlorine.
Option C: Phenols are a class of organic compounds containing a hydroxyl group bonded to an aromatic ring, not related to chlorine.
Option D: Alcohols are organic compounds characterized by the presence of a hydroxyl group (-OH), also not related to chlorine.
By precipitation of tuberculin, a purified protein derivative (PPD) is obtained. It is used in:
- A. Mantoux test
- B. Schick test
- C. Dick test
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A: Mantoux test. The Mantoux test is used to screen for tuberculosis by injecting PPD intradermally. The presence of a delayed hypersensitivity reaction indicates prior exposure to Mycobacterium tuberculosis. The Schick test (B) is used to test for immunity to diphtheria, while the Dick test (C) is used to test for immunity to scarlet fever. Therefore, the correct use of PPD is in the Mantoux test for tuberculosis screening.
The virus most commonly transmitted during pregnancy is:
- A. cytomegalovirus
- B. HIV
- C. herpes simplex virus
- D. Epstein-Barr virus
Correct Answer: A
Rationale: The correct answer is A: cytomegalovirus. CMV is the most common virus transmitted during pregnancy, leading to potential serious complications for the fetus. It can cause birth defects, hearing loss, and developmental delays. CMV is commonly spread through bodily fluids. HIV (B) can also be transmitted during pregnancy but is less common. Herpes simplex virus (C) can be transmitted but typically results in localized infection. Epstein-Barr virus (D) is not commonly transmitted during pregnancy.
Which of the following bacteria causes the disease diphtheria?
- A. Bordetella pertussis
- B. Corynebacterium diphtheriae
- C. Streptococcus pyogenes
- D. Neisseria meningitidis
Correct Answer: B
Rationale: The correct answer is B: Corynebacterium diphtheriae. This bacterium produces a toxin that causes diphtheria by inhibiting protein synthesis, leading to the formation of a pseudomembrane in the throat. Bordetella pertussis causes whooping cough, Streptococcus pyogenes causes strep throat, and Neisseria meningitidis causes meningitis. Corynebacterium diphtheriae is the only bacterium among the choices known to cause diphtheria due to its specific toxin production.