Nokea
The mold that produces penicillin is an example of:
- A. parasitism
- B. mutualism
- C. commensalism
- D. amensalism
Correct Answer: D
Rationale: The correct answer is D: amensalism. Penicillin mold produces a substance that inhibits the growth of bacteria, but it does not benefit nor harm the bacteria directly. This relationship is characterized by one organism (the mold) negatively affecting another (the bacteria) without any benefit or harm to itself. In parasitism (A), one organism benefits at the expense of another. In mutualism (B), both organisms benefit from the relationship. In commensalism (C), one organism benefits while the other is unaffected. Therefore, the mold producing penicillin fits the definition of amensalism.
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Patients with similar complaints applied to the doctor: weakness, pain in the intestines, disorder of GIT. Examination of the feces revealed that one patient with four nucleus cysts should be hospitalized immediately. For what protozoa are such cysts typical?
- A. Lamblia
- B. Dysenteric amoeba
- C. Balantidium
- D. Trichomonas
Correct Answer: B
Rationale: The correct answer is B: Dysenteric amoeba.
1. Dysenteric amoeba causes amoebiasis, which presents with symptoms like weakness, intestinal pain, and gastrointestinal disorders.
2. The presence of four-nucleus cysts in the feces indicates an infection with Entamoeba histolytica, the causative agent of amoebiasis.
3. Multiple-nucleus cysts are characteristic of Entamoeba histolytica, distinguishing it from other protozoa.
4. Lamblia (choice A), Balantidium (choice C), and Trichomonas (choice D) are not associated with four-nucleus cysts or the mentioned symptoms, making them incorrect choices.
In which of the following GIT infections, the bacteria adhere to the intestine wall and produce toxins
- A. Shigella spp.
- B. Salmonella spp.
- C. enterotoxigenic E. Coli (ETEC)
- D. Helicobacter pylori
Correct Answer: C
Rationale: The correct answer is C: enterotoxigenic E. Coli (ETEC). ETEC adheres to the intestine wall and produces toxins, leading to symptoms like diarrhea. Shigella spp. invade intestinal cells, Salmonella spp. cause inflammation, and Helicobacter pylori infects the stomach lining. This makes them incorrect choices for bacteria adhering to the intestine wall and producing toxins.
Which structure in bacteria is used for attachment to surfaces?
- A. Flagella
- B. Fimbriae
- C. Pili
- D. Capsule
Correct Answer: B
Rationale: The correct answer is B: Fimbriae. Fimbriae are short, hair-like appendages on the surface of bacteria that help in attachment to surfaces. They aid in colonization and biofilm formation. Flagella (A) are used for motility. Pili (C) are longer appendages used for conjugation and adherence to other cells. Capsules (D) are protective structures that aid in evading the host immune system, not necessarily for attachment.
Which bacteria are associated with causing foodborne infections?
- A. Clostridium botulinum
- B. Escherichia coli
- C. Salmonella enterica
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D (All of the above) because all three bacteria (Clostridium botulinum, Escherichia coli, Salmonella enterica) are known to cause foodborne infections. Clostridium botulinum can lead to botulism, E. coli can cause various gastrointestinal illnesses, and Salmonella enterica is a common cause of food poisoning. Each bacterium has specific mechanisms that result in foodborne illnesses. Choices A, B, and C are incorrect because each bacterium mentioned is associated with causing foodborne infections, making them collectively the correct answer.
Which of the following bacteria is associated with stomach ulcers?
- A. Escherichia coli
- B. Helicobacter pylori
- C. Bacillus cereus
- D. Clostridium difficile
Correct Answer: B
Rationale: The correct answer is B: Helicobacter pylori. This bacterium is associated with stomach ulcers as it can survive in the acidic environment of the stomach and produce substances that weaken the stomach lining. Escherichia coli (A) is associated with foodborne illnesses, not ulcers. Bacillus cereus (C) causes food poisoning. Clostridium difficile (D) is associated with antibiotic-associated colitis, not ulcers. Therefore, Helicobacter pylori is the correct answer based on its specific association with stomach ulcers.