Nokea
Which is NOT a property of interferon?
- A. Released from infected cells
- B. Acts extracellularly to inactivate virus
- C. Coded for by cellular DNA
- D. Not virus-specific but is cell-specific
Correct Answer: D
Rationale: Interferon is a cell-specific protein that is produced and released from infected cells in response to viral infections. It acts extracellularly to interfere with viral replication, not to inactivate the virus itself. Interferon is not coded for by cellular DNA, but by viral RNA during infection. Therefore, the correct answer, D, is that interferon is not virus-specific but is cell-specific. This is because interferon can be produced by various cell types in response to different types of viral infections, making it a broad-spectrum antiviral defense mechanism.
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Humoral factors of the natural resistance are:
- A. Macrophages and macrophages
- B. Lysozyme, lactoferrin, interferon, complement
- C. B and T lymphocytes, NK cells
- D. Immunoglobulins A, G and M
Correct Answer: B
Rationale: The correct answer is B because lysozyme, lactoferrin, interferon, and complement are all humoral factors involved in natural resistance. Lysozyme and lactoferrin are antimicrobial proteins that help defend against pathogens. Interferon is a signaling protein that inhibits viral replication, while complement is a group of proteins that enhance the immune response by promoting inflammation and opsonization.
Choices A, C, and D are incorrect:
- Choice A mentions only macrophages, which are not humoral factors but rather phagocytic cells.
- Choice C lists immune cells involved in adaptive immunity (B and T lymphocytes, NK cells) rather than humoral factors of natural resistance.
- Choice D includes immunoglobulins, which are part of adaptive immunity, not natural resistance.
A unique number that aids in finding additional toxicological information about a specific substance is the
- A. CAS number.
- B. atomic number.
- C. DOT ID number.
- D. RTECS number.
Correct Answer: D
Rationale: The correct answer is D: RTECS number. The Registry of Toxic Effects of Chemical Substances (RTECS) number is a unique identifier assigned to chemicals and substances known to cause toxicological effects. It aids in accessing detailed toxicological information such as acute toxicity, carcinogenicity, and mutagenicity. The CAS number (A) is a unique numerical identifier for chemical compounds, not specifically for toxicological information. The atomic number (B) is the number of protons in an element's nucleus, unrelated to toxicology. The DOT ID number (C) is used for hazardous materials transportation, not for toxicological information. Therefore, the RTECS number is the correct choice for finding toxicological information about a specific substance.
A patient with a sore throat had a throat smear revealing Gram-positive cocci in pairs with a capsule. What is the most likely causative agent?
- A. Streptococcus pneumoniae
- B. Neisseria meningitidis
- C. Haemophilus influenzae
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: Rationale:
1. Gram-positive cocci in pairs indicate Streptococcus pneumoniae.
2. Presence of a capsule points to S. pneumoniae as it has a polysaccharide capsule.
3. S. pneumoniae commonly causes sore throat.
4. Neisseria meningitidis, Haemophilus influenzae, and Klebsiella pneumoniae are not typically associated with sore throat.
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.
Which of the following bacteria is capable of surviving in extreme heat?
- A. Escherichia coli
- B. Bacillus subtilis
- C. Staphylococcus aureus
- D. Clostridium botulinum
Correct Answer: B
Rationale: The correct answer is B: Bacillus subtilis. Bacillus subtilis is a thermophilic bacterium capable of surviving in extreme heat due to its heat-resistant spores. It forms spores when exposed to unfavorable conditions, allowing it to withstand high temperatures. Escherichia coli (A), Staphylococcus aureus (C), and Clostridium botulinum (D) are mesophilic bacteria that do not have the same heat resistance mechanisms as Bacillus subtilis, making them unable to survive in extreme heat conditions.