Nokea
Which bacteria are capable of forming spores to survive in extreme conditions?
- A. Clostridium botulinum
- B. Bacillus anthracis
- C. Both A and B
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C because both Clostridium botulinum and Bacillus anthracis are capable of forming spores to survive in extreme conditions. Clostridium botulinum is known for causing botulism and produces highly heat-resistant spores, while Bacillus anthracis is the causative agent of anthrax and also forms spores. Choice A is incorrect because only Clostridium botulinum is mentioned, not Bacillus anthracis. Choice B is incorrect because only Bacillus anthracis is mentioned, not Clostridium botulinum. Choice D is incorrect as it states that none of the bacteria can form spores, which is false based on the characteristics of Clostridium botulinum and Bacillus anthracis.
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This drug has a destructive effect on erythrocytic forms of malarial plasmodia and dysenteric amoebae. It is used for treatment and prevention of such diseases as malaria, amebiasis and interstitial disease. What drug is it?
- A. Chingamin
- B. Emetine hydrochloride
- C. Quinine
- D. Erythromycin
Correct Answer: C
Rationale: The correct answer is C: Quinine. Quinine is known for its destructive effect on erythrocytic forms of malarial plasmodia and dysenteric amoebae. It is commonly used for the treatment and prevention of diseases such as malaria, amebiasis, and interstitial disease. Quinine works by interfering with the parasite's ability to break down hemoglobin in red blood cells, ultimately leading to their destruction.
Incorrect choices:
A: Chingamin - Chingamin is not typically used to treat malaria, amebiasis, or interstitial disease.
B: Emetine hydrochloride - Emetine hydrochloride is primarily used for treating amoebic dysentery and is not commonly used for malaria treatment.
D: Erythromycin - Erythromycin is an antibiotic used to treat bacterial infections, not parasitic infections like malaria or amebiasis.
Which one is true about sexually transmitted infections?
- A. An example of sexually transmitted infection is the soft chancre
- B. Entry portal is only the mucus of the urogenital tract
- C. After the syphilis infection the developed immunity is life-lasting
- D. The sexually transmitted infections are typical for developing countries with low social status and low hygiene.
Correct Answer: A
Rationale: The correct answer is A because a soft chancre is a type of sexually transmitted infection caused by the bacterium Haemophilus ducreyi. It presents as a painless ulcer on the genitals. The other choices are incorrect. B is incorrect because STIs can enter the body through various routes, not only the urogenital tract mucosa. C is incorrect because immunity to syphilis is not lifelong; reinfection is possible. D is incorrect because STIs can occur in any country regardless of social status or hygiene levels.
Carious cavities of a 29-year-old patient contain the parasitic protozoa. It is established that they relate to the Sarcodina class. Specify these single-celled organisms:
- A. Entamoeba gingivalis
- B. Entamoeba histolutica
- C. Entamoeba coli
- D. Amoeba proteus
Correct Answer: A
Rationale: The correct answer is A: Entamoeba gingivalis. Firstly, it is important to note that Entamoeba gingivalis is commonly found in the oral cavity, specifically in carious cavities. Secondly, Entamoeba gingivalis belongs to the Sarcodina class, which is characterized by their amoeboid movement using pseudopods. This protozoa is associated with oral health issues, particularly in individuals with poor oral hygiene.
Now, let's analyze why the other choices are incorrect:
B: Entamoeba histolutica is known for causing amoebic dysentery, not commonly associated with oral cavities.
C: Entamoeba coli is typically found in the human large intestine, not in oral cavities.
D: Amoeba proteus is a free-living amoeba commonly used in laboratory studies and not typically associated with oral cavity infections.
Bacteria that have a single polar flagellum at one end are referred to as:
- A. monotrichous
- B. monotrichous
- C. amphitrichous
- D. peritrichous
Correct Answer: B
Rationale: Step-by-step rationale:
1. Monotrichous means having a single flagellum at one end.
2. The term "polar" indicates that the flagellum is located at one end of the bacterium.
3. Therefore, bacteria with a single polar flagellum are referred to as monotrichous.
4. Choice A is a typo, as it is the same as the correct answer B.
Summary:
- Choice A is a typo, as it duplicates the correct answer.
- Choice C, amphitrichous, refers to bacteria with a flagellum at each end.
- Choice D, peritrichous, describes bacteria with flagella distributed over the entire surface.
The optochin sensitivity test demonstrates:
- A. Neisseria gonorrhoeae
- B. Pneumococcal
- C. Staphylococci
- D. Group A streptococci
Correct Answer: B
Rationale: The optochin sensitivity test is used to differentiate Pneumococcal (Streptococcus pneumoniae) from other streptococci. Optochin sensitivity is a characteristic feature of Pneumococcal, as it inhibits its growth. The test involves placing optochin discs on a culture plate and observing the zone of inhibition around the disc for Pneumococcal. Neisseria gonorrhoeae, Staphylococci, and Group A streptococci do not exhibit optochin sensitivity, making them incorrect choices. In summary, the optochin sensitivity test is specific to Pneumococcal, making choice B the correct answer.