Nokea
Transduction is:
- A. Transformation
- B. Transfer of genetic material between donor and recipient bacterial cells with the help of latent phage
- C. Transfer of large plasmids from a donor cell to a recipient cell
- D. None of the above
Correct Answer: B
Rationale: Transduction is the transfer of genetic material between bacterial cells with the help of a phage (virus). This process involves a phage infecting a bacterial cell, replicating inside it, and then transferring bacterial DNA along with phage DNA to another bacterial cell. This is different from transformation (choice A) which involves the uptake of naked DNA by a bacterial cell and plasmid transfer (choice C) which involves the transfer of small, circular DNA molecules. Therefore, the correct answer is B because it specifically describes the process of transduction in bacteria, while choices A and C describe different mechanisms of genetic transfer.
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Which of the following best describes bacterial conjugation?
- A. Transfer of DNA through a sex pilus
- B. Uptake of free DNA from the environment
- C. Transfer of DNA by bacteriophages
- D. Binary fission
Correct Answer: A
Rationale: The correct answer is A because bacterial conjugation involves the transfer of genetic material through a sex pilus from a donor bacterium to a recipient bacterium. This process allows for the exchange of genetic material and can lead to increased genetic diversity within bacterial populations.
Option B is incorrect because the uptake of free DNA from the environment is known as transformation, not conjugation. Option C is incorrect as transfer of DNA by bacteriophages is called transduction, not conjugation. Option D is incorrect because binary fission is a form of asexual reproduction in bacteria, not a mechanism for genetic exchange.
Which of the following viruses does not belong to family Paramyxoviridae:
- A. Measles virus
- B. Respiratory syncytial virus
- C. Mumps virus
- D. Rubella virus
Correct Answer: D
Rationale: The correct answer is D: Rubella virus. Rubella virus does not belong to the family Paramyxoviridae because it belongs to the Togaviridae family. The other choices, A (Measles virus), B (Respiratory syncytial virus), and C (Mumps virus) are all members of the Paramyxoviridae family. This classification is based on the genetic and structural characteristics of the viruses. Rubella virus is distinct in its genetic composition and replication cycle compared to the Paramyxoviridae family, making it the correct choice.
A patient presents with a history of diarrhea of several weeks duration. Which of the following may be the cause?
- A. Yersinia enterocolitica
- B. Bordetella pertussis
- C. Neisseria meningitidis
- D. Corynebacterium diphtheria
Correct Answer: A
Rationale: Rationale:
- Yersinia enterocolitica is a common cause of diarrhea due to contaminated food or water.
- It typically presents with symptoms such as abdominal pain, fever, and diarrhea.
- The other choices are unlikely causes of prolonged diarrhea, as Bordetella pertussis causes whooping cough, Neisseria meningitidis causes meningitis, and Corynebacterium diphtheria causes diphtheria.
Which bacteria are most commonly associated with hospital-acquired infections?
- A. Staphylococcus aureus
- B. Escherichia coli
- C. Klebsiella pneumoniae
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D: All of the above. Hospital-acquired infections can be caused by a variety of bacteria commonly found in healthcare settings. Staphylococcus aureus is a common cause of surgical site infections. Escherichia coli can cause urinary tract infections. Klebsiella pneumoniae is associated with pneumonia and bloodstream infections. Therefore, all three bacteria are frequently implicated in hospital-acquired infections due to their prevalence and ability to cause different types of infections in healthcare settings. Thus, the correct answer is D, as all of the listed bacteria are commonly associated with hospital-acquired infections.
Which bacteria is known for producing a neurotoxin that causes botulism?
- A. Clostridium botulinum
- B. Clostridium tetani
- C. Streptococcus pneumoniae
- D. Escherichia coli
Correct Answer: A
Rationale: Step-by-step rationale:
1. Clostridium botulinum is known for producing the neurotoxin causing botulism.
2. Botulinum toxin paralyzes muscles, leading to symptoms of botulism.
3. Clostridium tetani produces tetanus toxin causing muscle rigidity, not botulism.
4. Streptococcus pneumoniae causes pneumonia, not botulism.
5. Escherichia coli can cause food poisoning, but not botulism.
Summary:
Choice A is correct (Clostridium botulinum) due to its association with botulism and neurotoxin production. Choices B, C, and D are incorrect as they are associated with different diseases and toxins.