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Which bacterium is known for causing food poisoning due to its production of enterotoxins?
- A. Staphylococcus aureus
- B. Clostridium botulinum
- C. Salmonella enterica
- D. Vibrio cholerae
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus aureus. This bacterium causes food poisoning by producing enterotoxins that lead to symptoms like nausea and vomiting. Staphylococcus aureus can survive in various food items and multiply rapidly, producing toxins that are heat-stable. Clostridium botulinum causes botulism due to neurotoxins, not enterotoxins. Salmonella enterica causes gastrointestinal infections, not primarily food poisoning. Vibrio cholerae causes cholera by producing a toxin that leads to severe watery diarrhea and dehydration, not enterotoxins like Staphylococcus aureus.
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Cytomegalovirus infections are caused by the human herpesvirus:
- A. 2
- B. 3
- C. 4
- D. 5
Correct Answer: D
Rationale: The correct answer is D because Cytomegalovirus infections are caused by human herpesvirus 5, also known as Human Herpesvirus 5 (HHV-5) or Cytomegalovirus (CMV). This virus belongs to the Herpesviridae family, genus Betaherpesvirinae. Options A, B, and C are incorrect as they do not correspond to the specific virus responsible for causing Cytomegalovirus infections.
Microscopic examination of a Gramstained scrape from patient's tongue revealed oval, round, elongated chains of dark-violet gemmating cells. What disease can be caused by this causative agent?
- A. Candidosis
- B. Actinomycosis
- C. Diphtheria
- D. Staphylococcic infection
Correct Answer: A
Rationale: Step 1: Oval, round, elongated chains of gemmating cells indicate yeast-like budding cells seen in Candida species.
Step 2: Candidosis is caused by Candida species, which is commonly found in the oral cavity and can cause infections on the tongue.
Step 3: Candidosis presents as white patches or plaques on the tongue.
Step 4: Therefore, the correct answer is A: Candidosis.
Summary:
B: Actinomycosis is caused by Actinomyces species, which are filamentous bacteria, not oval budding cells.
C: Diphtheria is caused by Corynebacterium diphtheriae, which appears as gram-positive rods in chains, not oval budding cells.
D: Staphylococcal infections are caused by Staphylococcus species, which appear as clusters of cocci, not oval budding cells.
The bacterial component targeted by penicillin is:
- A. DNA
- B. Plasma membrane
- C. Cell wall
- D. Ribosomes
Correct Answer: C
Rationale: The correct answer is C: Cell wall. Penicillin targets the cell wall of bacteria by inhibiting the formation of peptidoglycan, a crucial component of the cell wall. This weakens the cell wall, leading to bacterial cell lysis. Choice A (DNA) is incorrect because penicillin does not directly target DNA. Choice B (Plasma membrane) is incorrect as penicillin primarily affects the cell wall, not the plasma membrane. Choice D (Ribosomes) is incorrect because penicillin does not target bacterial ribosomes, which are involved in protein synthesis.
Hepatitis B infection may present with:
- A. Jaundice
- B. Elevated serum aminotransferase levels
- C. No symptoms
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D: All of the above. Hepatitis B infection can present with jaundice due to liver inflammation, elevated serum aminotransferase levels due to liver damage, and sometimes no symptoms in the acute phase. This comprehensive presentation covers the spectrum of possible clinical manifestations of hepatitis B infection. Choices A and B are correct as they are common manifestations of hepatitis B infection. Choice C is incorrect as hepatitis B infection can indeed present with symptoms, making option D the most appropriate choice.
The term used to indicate the extent to which a drug reaches its site of action is:
- A. bioactivity
- B. bioavailability
- C. bioremediation
- D. biostasis
Correct Answer: B
Rationale: The correct answer is B: bioavailability. Bioavailability refers to the extent and rate at which a drug reaches its site of action in the body. This includes factors such as absorption, distribution, metabolism, and excretion.
Rationale:
1. Bioactivity refers to the pharmacological effect of a drug, not how effectively it reaches its site of action.
2. Bioremediation is the process of using organisms to remove or neutralize pollutants, not related to drug delivery.
3. Biostasis refers to a state of equilibrium or balance in living organisms, not related to drug transport to its site of action.
In summary, bioavailability is the most appropriate term as it specifically addresses the process of a drug reaching its intended target within the body, distinguishing it from the other choices.