Nokea
Lipopolysaccharides (LPS) are found in:
- A. Gram-positive bacteria
- B. Fungal cell walls
- C. Gram-negative bacterial outer membrane
- D. Viral capsids
Correct Answer: C
Rationale: The correct answer is C: Gram-negative bacterial outer membrane. Lipopolysaccharides (LPS) are major components of the outer membrane of Gram-negative bacteria. LPS consist of lipid A, core oligosaccharide, and O-antigen. They play a crucial role in the structural integrity and protection of Gram-negative bacteria.
Choice A (Gram-positive bacteria) is incorrect because LPS are not present in Gram-positive bacteria. Choice B (Fungal cell walls) is incorrect as LPS are specific to bacterial outer membranes. Choice D (Viral capsids) is incorrect as LPS are not associated with viral structures.
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Which of the following bacteria is responsible for causing the disease known as syphilis?
- A. Treponema pallidum
- B. Neisseria gonorrhoeae
- C. Chlamydia trachomatis
- D. Escherichia coli
Correct Answer: A
Rationale: The correct answer is A: Treponema pallidum. This bacterium is responsible for causing syphilis due to its unique spiral shape and ability to penetrate mucous membranes. It is transmitted through sexual contact or from mother to child during childbirth. Neisseria gonorrhoeae causes gonorrhea, Chlamydia trachomatis causes chlamydia, and Escherichia coli is a common bacterium found in the gut. Therefore, they are not responsible for syphilis.
During a microbiology session, students observed flagellated protozoa with an undulating membrane in vaginal discharge samples. What is the causative agent?
- A. Trichomonas vaginalis
- B. Giardia lamblia
- C. Trypanosoma brucei
- D. Leishmania donovani
Correct Answer: A
Rationale: The correct answer is A: Trichomonas vaginalis. Trichomonas vaginalis is a flagellated protozoa that causes the sexually transmitted infection trichomoniasis. The presence of an undulating membrane in vaginal discharge samples is characteristic of Trichomonas vaginalis. Giardia lamblia causes gastrointestinal illness, not vaginal infections. Trypanosoma brucei causes African sleeping sickness transmitted by tsetse flies. Leishmania donovani causes visceral leishmaniasis transmitted by sandflies.
Which of the following bacteria are capable of forming spores?
- A. Staphylococcus aureus
- B. Clostridium botulinum
- C. Escherichia coli
- D. Neisseria gonorrhoeae
Correct Answer: B
Rationale: The correct answer is B, Clostridium botulinum. This bacterium is capable of forming spores, which are dormant, resistant structures that help bacteria survive harsh conditions. Staphylococcus aureus (A), Escherichia coli (C), and Neisseria gonorrhoeae (D) do not form spores. Staphylococcus aureus is a gram-positive bacterium that does not produce spores. Escherichia coli is a gram-negative bacterium that also does not form spores. Neisseria gonorrhoeae is a gram-negative bacterium and does not have the ability to form spores. Therefore, the only bacteria among the options that can form spores is Clostridium botulinum.
Which one is an example of an immunomodulator
- A. Pentaxim
- B. Hexacima
- C. Gamma-interferon
- D. Rifampin
Correct Answer: C
Rationale: Step-by-step rationale for why C is correct:
1. Immunomodulators regulate the immune response.
2. Gamma-interferon is a cytokine that enhances immune function.
3. It helps fight infections and regulate inflammation.
4. Pentaxim and Hexacima are combination vaccines.
5. Rifampin is an antibiotic, not an immunomodulator.
Summary:
- A and B are combination vaccines.
- D is an antibiotic.
- C is the correct answer as gamma-interferon is an immunomodulator that regulates the immune response.
Bacteriological examination of the urine of the patient with pyelonephritis revealed microorganisms that produced yellow-green pigment and a characteristic odor in meat-peptone agar. What are they called?
- A. Pseudomonas B.Escherichia C.Proteus D.Klebsiella E.Azotobacter
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas. Pseudomonas bacteria are known to produce yellow-green pigment and a characteristic odor, specifically in meat-peptone agar. This is due to the production of pyoverdin pigment by Pseudomonas. Other choices like Escherichia, Proteus, Klebsiella, and Azotobacter do not typically produce yellow-green pigment or have a characteristic odor in meat-peptone agar. Therefore, based on the specific characteristics mentioned in the question, Pseudomonas is the most appropriate choice.