Nokea
Viruses that are mainly transmitted through sexual contact are:
- A. Arenaviruses
- B. Togaviruses
- C. Papillomaviruses
- D. Polyomaviruses
Correct Answer: C
Rationale: The correct answer is C: Papillomaviruses. Papillomaviruses are primarily transmitted through sexual contact, as they infect the skin and mucous membranes of the genital area. This transmission route is well-documented through research and epidemiological studies. Arenaviruses (A) are primarily transmitted through contact with infected rodents, not sexual contact. Togaviruses (B) are mainly transmitted by mosquitoes and ticks. Polyomaviruses (D) are typically spread through respiratory secretions or contaminated urine, not through sexual contact. Therefore, the most appropriate choice for viruses transmitted mainly through sexual contact is Papillomaviruses (C).
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Which bacteria is responsible for causing the disease known as whooping cough?
- A. Clostridium botulinum
- B. Bordetella pertussis
- C. Streptococcus pneumoniae
- D. Neisseria meningitidis
Correct Answer: B
Rationale: The correct answer is B: Bordetella pertussis. This bacterium causes whooping cough by infecting the respiratory tract. It produces toxins that lead to severe coughing fits characteristic of the disease. Clostridium botulinum (A) causes botulism, Streptococcus pneumoniae (C) causes pneumonia, and Neisseria meningitidis (D) causes meningitis, not whooping cough. B. pertussis is the only bacterium specifically associated with whooping cough.
A bacteriological laboratory tests canned meat for botulinum toxin. Extract of the tested material and ABE botulinum antitoxin serum was introduced into the test group of mice; a control group of mice received the extract without antibotulinic serum. What serological reaction was used?
- A. Neutralization
- B. Precipitation
- C. Complement binding
- D. Double immunodiffusion
Correct Answer: A
Rationale: The correct answer is A: Neutralization. In this experiment, the ABE botulinum antitoxin serum is introduced along with the extract to neutralize the botulinum toxin. This is a specific type of serological reaction where the antitoxin serum binds to and neutralizes the toxin, preventing it from causing harm.
Summary:
- B: Precipitation involves the formation of visible insoluble complexes, which is not the case in this experiment.
- C: Complement binding involves the activation of complement proteins, which is not the main mechanism at play here.
- D: Double immunodiffusion is a technique to detect the presence of specific antigens or antibodies, but it is not directly related to the neutralization of toxins as seen in this experiment.
The main structure components of Viruses are:
- A. Glycoproteins and proteins
- B. Nucleic acids and lipids
- C. Nucleic acid and proteins
- D. Lipids and proteins
Correct Answer: C
Rationale: The correct answer is C: Nucleic acid and proteins. Viruses contain genetic material in the form of nucleic acids (DNA or RNA) surrounded by a protein coat. This genetic material carries instructions for viral replication. Proteins are also essential components of viruses, serving various functions like facilitating viral entry into host cells. Option A is incorrect as lipids are not main components of viruses. Option B is incorrect as lipids are not typically found in the main structure of viruses. Option D is incorrect as lipids are not primary components of viruses, and glycoproteins are not always present in the main structure of viruses.
Which of the following organisms produces toxins that target cholesterol?
- A. Streptococcus pyogenes
- B. Corynebacterium diphtheriae
- C. Escherichia coli
- D. Aeromonas hydrophila
Correct Answer: C
Rationale: Step 1: Escherichia coli is known to produce a toxin called colibactin that targets cholesterol.
Step 2: Colibactin disrupts cholesterol metabolism in host cells.
Step 3: This disruption can lead to various health issues.
Step 4: Streptococcus pyogenes produces different toxins, not specifically targeting cholesterol.
Step 5: Corynebacterium diphtheriae produces diphtheria toxin, not targeting cholesterol.
Step 6: Aeromonas hydrophila produces various toxins, but not known for targeting cholesterol.
Summary: Escherichia coli produces toxins that specifically target cholesterol, making it the correct choice over the other options.
Which organism is responsible for cholera?
- A. Salmonella typhi
- B. Vibrio cholerae
- C. Escherichia coli
- D. Shigella dysenteriae
Correct Answer: B
Rationale: The correct answer is B: Vibrio cholerae. Cholera is caused by this specific bacterium. Vibrio cholerae produces a toxin that leads to severe diarrhea and dehydration. Salmonella typhi causes typhoid fever, Escherichia coli can cause various infections but not cholera, and Shigella dysenteriae causes dysentery, not cholera. Therefore, the correct choice is B.