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What is the mechanism of action of the exotoxin C. Diphtheriae?
- A. Inhibits the release of acetylcholine
- B. Blocks the inhibitory neurotransmitters release
- C. Inhibits protein synthesis
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C: Inhibits protein synthesis. Exotoxin of C. Diphtheriae acts by inhibiting protein synthesis in host cells. This disrupts cellular functions and leads to tissue damage. Choice A is incorrect because acetylcholine release is not affected. Choice B is incorrect as it does not involve neurotransmitters. Choice D is incorrect as the exotoxin does have a specific mechanism.
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A Gram-stained sputum smear revealed Gram-positive rods in chains with central spores. The patient presented with severe pneumonia. What is the causative agent?
- A. Bacillus anthracis
- B. Clostridium tetani
- C. Streptococcus pneumoniae
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Bacillus anthracis. The presence of Gram-positive rods in chains with central spores on the Gram stain indicates Bacillus anthracis. This bacterium is known to cause severe pneumonia. Clostridium tetani does not typically cause pneumonia but rather tetanus. Streptococcus pneumoniae is a Gram-positive cocci, not rods. Klebsiella pneumoniae is a Gram-negative bacterium commonly associated with pneumonia, but it does not form central spores.
For treatment of Anthrax are used
- A. Penicillins, tetracyclins, macrolides
- B. anti-anthrax gamma-globulins
- C. anti-anthrax immune-serum
- D. all of the above
Correct Answer: D
Rationale: The correct answer is D because the treatment for Anthrax involves using antibiotics such as penicillins, tetracyclines, and macrolides to target the bacteria. Anti-anthrax gamma-globulins and immune-serum are used to provide passive immunity, but they are not the primary treatment. Therefore, options A, B, and C are incorrect as they do not encompass all the necessary components for treating Anthrax. Overall, using a combination of antibiotics and immune-based treatments like gamma-globulins and immune-serum provides a comprehensive approach to managing Anthrax infection.
For Parvovirus B19 is true that:
- A. Causes HBV
- B. Causes AIDS
- C. Causes erythema infectiosum
- D. Causes measles
Correct Answer: C
Rationale: The correct answer is C because Parvovirus B19 causes erythema infectiosum, also known as fifth disease. This virus primarily affects children and causes a distinctive red rash on the cheeks, arms, and legs. It is not associated with causing HBV (Hepatitis B Virus), AIDS, or measles. Parvovirus B19 specifically targets red blood cell precursors, leading to anemia in some cases. Understanding the characteristic clinical presentation and pathophysiology of the virus helps in selecting the correct answer.
In which phase of mitosis do the chromatids separate?
- A. Prophase
- B. Metaphase
- C. Anaphase
- D. Telophase
Correct Answer: C
Rationale: In anaphase, sister chromatids separate and move towards opposite poles of the cell. This is facilitated by the shortening of microtubules attached to the centromeres. Prophase is the phase where chromosomes condense and the nuclear envelope breaks down. Metaphase is when chromosomes align at the metaphase plate. Telophase is when the nuclear envelope reforms and chromosomes decondense. Therefore, anaphase is the correct phase for chromatid separation.
A laboratory received a food product that had been taken from the focus of food poisoning and presumably contained botulinum toxin. To identify the type of toxin, the neutralization reaction must be performed on white mice. What biological product is used in this reaction?
- A. Antitoxic serum
- B. Normal serum
- C. Antibacterial serum
- D. Diagnosticum
Correct Answer: A
Rationale: The correct answer is A: Antitoxic serum. In the neutralization reaction to identify botulinum toxin, antitoxic serum is used to neutralize the toxin in white mice. Antitoxic serum contains antibodies that specifically target and neutralize the botulinum toxin. Normal serum (B) does not contain the necessary antibodies to neutralize the toxin. Antibacterial serum (C) is not effective against toxins like botulinum. Diagnosticum (D) is a general term and does not specifically refer to the biological product required for this reaction.