Nokea
Pili are also called:
- A. fimbriae
- B. microvilli
- C. cilia
- D. flagella
Correct Answer: B
Rationale: The correct answer is B: microvilli. Pili are hair-like structures found on the surface of some bacteria, while microvilli are microscopic cellular projections that increase surface area for absorption in cells like intestinal cells. Pili are involved in bacterial adhesion, while microvilli are important for nutrient absorption. Therefore, the correct answer is B.
Incorrect choices:
A: Fimbriae are short, thin appendages found on the surface of some bacteria, mainly used for adhesion.
C: Cilia are hair-like structures found on the surface of some eukaryotic cells, often involved in movement or sensory functions.
D: Flagella are long, whip-like appendages used for bacterial motility.
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What clinical specimen can be analysed in the diagnosis of sexually transmitted infections:
- A. Genital ulcer secretion
- B. Lymph node punctate
- C. Serum
- D. All are correct
Correct Answer: D
Rationale: Certainly! The correct answer is D because all three options (A, B, and C) can be analyzed in the diagnosis of sexually transmitted infections. Genital ulcer secretions can reveal the presence of pathogens causing STIs, lymph node punctate can indicate systemic infection, and serum can be tested for specific STI antibodies. Therefore, all these clinical specimens are essential for a comprehensive diagnosis of sexually transmitted infections. The other choices (A, B, C) are incorrect as they individually represent important specimens used in the diagnosis process.
Which type of bacteria have an outer membrane containing lipopolysaccharides (LPS)?
- A. Gram-positive bacteria
- B. Gram-negative bacteria
- C. Both Gram-positive and Gram-negative bacteria
- D. Neither Gram-positive nor Gram-negative bacteria
Correct Answer: B
Rationale: The correct answer is B: Gram-negative bacteria. Gram-negative bacteria have an outer membrane containing lipopolysaccharides (LPS). In the Gram staining technique, these bacteria appear pink/red due to the thin peptidoglycan layer, which allows the crystal violet stain to be washed out, revealing the safranin counterstain. Gram-positive bacteria (choice A) have a thick peptidoglycan layer but lack an outer membrane with LPS. Choice C is incorrect since only Gram-negative bacteria possess LPS in their outer membrane. Choice D is incorrect as all bacteria can be classified as either Gram-positive or Gram-negative based on their cell wall structure.
Lysozyme acts on the bacterial:
- A. cytoplasm
- B. cell wall
- C. nucleus
- D. capsule
Correct Answer: B
Rationale: The correct answer is B: cell wall. Lysozyme is an enzyme that targets the cell wall of bacteria by breaking down the peptidoglycan layer, leading to bacterial cell lysis. This action disrupts the structural integrity of the bacteria, ultimately causing their death. Choices A, C, and D are incorrect because lysozyme does not target the cytoplasm, nucleus, or capsule of bacteria. The primary function of lysozyme is to act on the cell wall, making option B the correct answer in this context.
The sample used to proving epidemic meningitis is:
- A. CSF transported at 37°C (CSF sample, blood, nasopharyngeal secretion)
- B. Feces
- C. CSF transported at +4°C
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A because CSF (Cerebrospinal fluid) is the sample used for proving epidemic meningitis. It should be transported at 37°C to maintain its integrity. Blood and nasopharyngeal secretions are not typically used for diagnosing meningitis. Choice B, feces, is unrelated to the diagnosis of meningitis. Choice C, CSF transported at +4°C, is incorrect as it should be transported at 37°C to prevent degradation of the sample. Therefore, A is the correct choice for proving epidemic meningitis due to the specificity of the sample and the proper transport conditions.
Which bacteria are capable of surviving in anoxic (oxygen-free) conditions?
- A. Obligate anaerobes
- B. Facultative anaerobes
- C. Obligate aerobes
- D. Microaerophiles
Correct Answer: A
Rationale: The correct answer is A: Obligate anaerobes. These bacteria can only survive in the absence of oxygen as they lack the enzymes needed for aerobic respiration. They typically use fermentation or anaerobic respiration for energy production.
Incorrect choices:
B: Facultative anaerobes can switch between aerobic and anaerobic metabolism based on oxygen availability.
C: Obligate aerobes require oxygen for survival and cannot survive in anoxic conditions.
D: Microaerophiles require low levels of oxygen for growth and are not capable of surviving in completely anoxic conditions.