Nokea
Precipitation reaction can be converted into agglutination reaction by coating soluble antigen onto
- A. Bentonite (clay) particles
- B. RBCs
- C. Latex particles
- D. All of these
Correct Answer: D
Rationale: The correct answer is D: All of these. Coating soluble antigen onto Bentonite particles, RBCs, or Latex particles can convert a precipitation reaction into an agglutination reaction. This is because soluble antigens bind to their specific antibodies, causing the particles to clump together, visible as agglutination. Bentonite particles, RBCs, and Latex particles all provide surfaces for the antigen-antibody interaction to occur, leading to agglutination. Therefore, all of these options are correct for converting precipitation reactions to agglutination reactions.
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Slime, blood and protozoa 30-200 microns of length have been revealed in a man's feces. The body is covered with cilias and has correct oval form with a little bit narrowed forward and wide round shaped back end. On the forward end a mouth is visible. In cytoplasm there are two nucleuses and two short vacuoles. For whom are the described attributes typical?
- A. Balantidium
- B. Lamblia
- C. Dysenteric amoeba
- D. Trichomonas
Correct Answer: A
Rationale: Rationale: The described attributes match those of Balantidium. The presence of cilia, oval shape with a narrowed front and wide back end, visible mouth, two nucleuses, and short vacuoles are all characteristic features of Balantidium. Balantidium is a ciliated protozoan parasite commonly found in the human intestine. The other choices can be eliminated based on specific characteristics: Lamblia lacks cilia and has a different shape, Dysenteric amoeba typically has a single nucleus, and Trichomonas does not have cilia or multiple nuclei. Therefore, based on the specific attributes described, the correct answer is Balantidium (Choice A).
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.
Which of the following pathogens has the widest infectious spectrum
- A. Anthrax bacillus
- B. mumps virus
- C. the causative agent of gonorrhea
- D. the rabies virus
Correct Answer: A
Rationale: The correct answer is A, Anthrax bacillus, because it has the widest infectious spectrum among the options provided. Anthrax bacillus can infect a wide range of hosts, including humans and various animals. It is known for its ability to survive in different environments and cause disease through various routes of exposure. In contrast, choices B, C, and D have more limited infectious spectra. Mumps virus primarily infects humans, the causative agent of gonorrhea mainly affects humans through sexual contact, and the rabies virus typically infects mammals through bites from infected animals. Therefore, Anthrax bacillus is the correct choice due to its broader range of hosts and modes of transmission compared to the other options.
Adenoviruses have helical capsids:
- A. TRUE
- B. FALSE
- C. Both answers can be correct depending on the given situation
- D. None of the above
Correct Answer: B
Rationale: Step 1: Adenoviruses are known to have icosahedral capsids, not helical.
Step 2: Helical capsids are typically found in viruses like tobacco mosaic virus.
Step 3: Therefore, the statement that adenoviruses have helical capsids is FALSE.
Summary: A is incorrect as adenoviruses do not have helical capsids. C is incorrect as there is no situation where adenoviruses have helical capsids. D is incorrect as there is a clear correct answer, which is B.
Which of the following is characteristic of obligate anaerobes?
- A. They require oxygen to survive
- B. They can survive in the presence or absence of oxygen
- C. They cannot tolerate oxygen
- D. They prefer low levels of oxygen
Correct Answer: C
Rationale: The correct answer is C: Obligate anaerobes cannot tolerate oxygen. They lack the enzymes needed to detoxify reactive oxygen species generated in the presence of oxygen. This makes them unable to survive in oxygen-rich environments. Choice A is incorrect because obligate anaerobes do not require oxygen to survive. Choice B is incorrect because obligate anaerobes specifically require the absence of oxygen. Choice D is incorrect because obligate anaerobes cannot even tolerate low levels of oxygen.