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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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.
What would be the conclusion?
- A. The water is safe for consumption
- B. The water quality is doubtful
- C. The water quality is extremely doubtful
- D. The water is polluted
Correct Answer: B
Rationale: Step-by-step rationale for choice B being correct:
1. The conclusion should be based on evidence or observations.
2. "Doubtful" suggests uncertainty, indicating lack of definitive safety.
3. Choice A is too absolute without considering potential risks.
4. Choice C uses extreme language without proper evidence.
5. Choice D is overly definitive without considering varying levels of contamination. Therefore, choice B is the most reasonable conclusion.
Treponemae are motile because of:
- A. axial filaments
- B. mans peritrichous filaments
- C. single monotrichous filament
- D. fimbriae
Correct Answer: A
Rationale: The correct answer is A: axial filaments. Treponemae are motile due to their unique structure of axial filaments, also known as endoflagella. These axial filaments are located within the periplasmic space of the organism and are responsible for the corkscrew-like motility of Treponemae. The other choices (B: mans peritrichous filaments, C: single monotrichous filament, D: fimbriae) do not play a role in the motility of Treponemae. Peritrichous filaments and single monotrichous filaments are not present in Treponemae, and fimbriae are primarily involved in adhesion rather than motility.
Algae that contain agar in their cell walls belong to:
- A. Chrysophyta
- B. Rhodophyta
- C. Chlorophyta
- D. Phaeophyta
Correct Answer: B
Rationale: The correct answer is B: Rhodophyta. Rhodophyta is the phylum of red algae, which are known to contain agar in their cell walls. Agar is a gelatinous substance derived from these algae. Chrysophyta (A), Chlorophyta (C), and Phaeophyta (D) do not typically contain agar in their cell walls. Chrysophyta includes diatoms, Chlorophyta includes green algae, and Phaeophyta includes brown algae, none of which are known for agar production. Therefore, Rhodophyta is the correct choice based on the presence of agar in their cell walls.
Which of the following is used to test for bacterial antibiotic susceptibility?
- A. Gram stain
- B. Catalase test
- C. Kirby-Bauer disk diffusion test
- D. Endospore stain
Correct Answer: C
Rationale: The correct answer is C: Kirby-Bauer disk diffusion test. This test is used to determine the antibiotic susceptibility of bacteria by measuring the zone of inhibition around antibiotic-soaked paper disks. It helps identify which antibiotics are effective against the bacteria being tested. This test is crucial in guiding antibiotic treatment decisions.
A: Gram stain is used to classify bacteria based on their cell wall composition and morphology, not for antibiotic susceptibility testing.
B: Catalase test is used to differentiate between catalase-positive and catalase-negative bacteria, not for antibiotic susceptibility testing.
D: Endospore stain is used to detect the presence of endospores in bacteria, not for antibiotic susceptibility testing.