Nokea
A bacteriophage is a(n) ____________ virus.
- A. helical
- B. icosahedral
- C. enveloped
- D. complex
Correct Answer: D
Rationale: The correct answer is D: complex. Bacteriophages are considered complex viruses because they have a complex structure consisting of a polyhedral head, a helical tail, and tail fibers. The head contains the viral genetic material, while the tail facilitates attachment to the host bacterial cell. This complexity distinguishes bacteriophages from simpler viruses like helical and icosahedral viruses. Helical viruses have a rod-like shape, while icosahedral viruses have a symmetrical, 20-sided structure. Enveloped viruses have a lipid bilayer envelope surrounding their capsid, which bacteriophages lack. Therefore, the unique and intricate structure of bacteriophages classifies them as complex viruses.
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Which of the following is not considered to be a vehicle transmission?
- A. Airborne
- B. Insect
- C. Foodborne
- D. Bodily fluid
Correct Answer: B
Rationale: The correct answer is B: Insect. A vehicle transmission refers to the mode by which a disease spreads from one host to another. Insects can transmit diseases, making them a vehicle for transmission. Airborne, foodborne, and bodily fluid transmissions are well-known modes of disease spread, while insects are also known vectors for diseases like malaria and Zika.
The process of bacterial conjugation involves:
- A. DNA transfer via bacteriophage
- B. Uptake of naked DNA from the environment
- C. Direct transfer of DNA between two bacterial cells
- D. Binary fission
Correct Answer: C
Rationale: The correct answer is C: Direct transfer of DNA between two bacterial cells. In bacterial conjugation, genetic material is transferred directly from one bacterial cell to another through a conjugative pilus. This process involves physical contact between the cells, followed by the transfer of plasmid DNA or chromosomal DNA. This mechanism allows for the exchange of genetic information between bacteria, leading to genetic diversity.
Explanation of why other choices are incorrect:
A: DNA transfer via bacteriophage - Bacteriophage is a virus that infects bacteria and transfers its genetic material, but this is not the mechanism involved in bacterial conjugation.
B: Uptake of naked DNA from the environment - This process is known as transformation, where bacteria take up free DNA from the environment, but it is not specific to bacterial conjugation.
D: Binary fission - Binary fission is a form of asexual reproduction in bacteria where a single cell divides into two identical cells, and it is not related to the process
The classic causative agent of croupous pneumonia is:
- A. Chlamydia pneumoniae
- B. Streptococcus pneumoniae
- C. Mycoplasmas pneumoniae
- D. Staphylococcus aureus
Correct Answer: B
Rationale: The correct answer is B, Streptococcus pneumoniae. This bacterium is the classic causative agent of croupous pneumonia due to its ability to infect the lungs and cause inflammation. Streptococcus pneumoniae is a common pathogen known for causing pneumonia in both adults and children. It is characterized by the presence of a capsule that helps it evade the host immune system.
Choice A, Chlamydia pneumoniae, is not the correct answer as it is more commonly associated with atypical pneumonia. Choice C, Mycoplasma pneumoniae, is also associated with atypical pneumonia and not croupous pneumonia. Choice D, Staphylococcus aureus, can cause pneumonia, but it is not the classic causative agent of croupous pneumonia.
Which of the following antibodies is synthesized by the infant soon after birth?
- A. IgA
- B. IgM
- C. IgG
- D. IgD
Correct Answer: B
Rationale: The correct answer is B: IgM. IgM is the first antibody synthesized by the infant soon after birth. It is produced by B cells in response to initial exposure to antigens. IgA is mainly found in mucosal areas, IgG is transferred from mother to fetus, and IgD functions in the early stages of B cell development. Therefore, IgM is the most suitable choice as the antibody synthesized by the infant soon after birth.
A 47-year-old male patient consulted a dentist about difficult mouth opening (lockjaw or trismus). The patient has a history of a stab wound of the lower extremity. What infection can be manifested by these symptoms?
- A. Tetanus
- B. Brucellosis
- C. Whooping cough
- D. Anaerobic wound infection
Correct Answer: A
Rationale: The correct answer is A: Tetanus. Tetanus is caused by the bacterium Clostridium tetani, commonly found in soil, dust, and animal feces. The patient's history of a stab wound increases the risk of tetanus infection as the bacterium can enter the body through the wound. Tetanus infection can lead to symptoms such as lockjaw or trismus, which are characterized by muscle stiffness and difficulty opening the mouth. This is due to the neurotoxin produced by Clostridium tetani affecting the muscles.
Summary of incorrect choices:
B: Brucellosis is a bacterial infection transmitted from animals to humans through consumption of unpasteurized dairy products. It does not typically manifest with symptoms of lockjaw.
C: Whooping cough (Pertussis) is a respiratory infection caused by Bordetella pertussis bacteria. It presents with severe coughing fits but does not cause lockjaw.
D: Anaerobic wound infection