microbiology chapter 11 test bank

Correct Answer: A

Rationale: The correct answer is A: Agglutination. Agglutination is commonly used to identify Vibrio cholerae by clumping together the bacteria with specific antibodies. This reaction occurs when antibodies bind to antigens on the bacterial surface, leading to visible clumps. In contrast, Precipitation, Western blot, and ELISA are not typically used to identify Vibrio cholerae. Precipitation involves antigen-antibody complexes becoming insoluble, Western blot is used for protein detection, and ELISA is commonly used for detecting specific antigens or antibodies in a sample. Agglutination is the most appropriate choice for identifying Vibrio cholerae due to its specific interaction with the bacteria's surface antigens.

Correct Answer: A

Rationale: The correct answer is A: Streptococcus pneumoniae. The presence of Gram-positive cocci in pairs with a capsule is characteristic of Streptococcus pneumoniae. This bacterium is a common cause of bacterial pharyngitis, leading to a severe sore throat. Staphylococcus aureus (B) does not typically present in pairs or have a capsule. Neisseria meningitidis (C) is a Gram-negative diplococcus, not a Gram-positive cocci. Klebsiella pneumoniae (D) is a Gram-negative bacillus, not a cocci. Thus, based on the characteristics described in the question, Streptococcus pneumoniae is the most likely causative agent.

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.

Correct Answer: C

Rationale: The pertussis toxin inhibits the adenylate cyclase-mediated conversion of ATP to cyclic AMP, leading to decreased levels of cyclic AMP in the cell. This disrupts important cellular signaling pathways, affecting immune response and causing symptoms of pertussis. Choices A, B, and D are incorrect because the pertussis toxin does not directly affect protein synthesis, provoke overproduction of mucus in tracheal cells, or provoke release of electrolytes.

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.