microbiology an evolving science test bank

Correct Answer: C

Rationale: The correct answer is C: Reaction type GRUBER. Agglutination reaction in GRUBER involves the clumping of particles due to specific antibodies binding to antigens on the surface. This reaction is commonly used in blood typing and serology tests. A: Western blot is a technique used to detect specific proteins in a sample, not related to agglutination. B: ELISA is an enzyme-linked immunosorbent assay used to detect antibodies or antigens, not based on agglutination. D: Ascoli ring test is a method to detect the presence of DNA in a sample, not related to agglutination.

Correct Answer: D

Rationale: The correct answer is D: Mycobacterium tuberculosis. This bacterium can be transmitted via droplets in the air through coughing or sneezing. It is spread through respiratory droplets containing the bacteria. Streptococcus pneumoniae (A) is transmitted through direct contact with respiratory secretions, not through droplets in the air. Escherichia coli (B) is commonly transmitted through contaminated food or water, not through the air. Clostridium botulinum (C) is typically transmitted through contaminated food, not via respiratory droplets. Therefore, the correct choice is D as it is the only bacterium listed that can be transmitted via droplets in the air.

Correct Answer: A

Rationale: The correct answer is A: Bordetella pertussis. This bacterium causes whooping cough by attaching to the respiratory tract and releasing toxins that lead to severe coughing fits. Clostridium tetani causes tetanus, not whooping cough. Haemophilus influenzae can cause respiratory infections but not specifically whooping cough. Staphylococcus aureus is known for causing skin infections and not respiratory diseases like whooping cough. Therefore, the presence of Bordetella pertussis and its specific mechanism of causing whooping cough makes it the correct answer.

Correct Answer: B

Rationale: Protein A is a virulence factor specific to Staphylococcus aureus. This protein binds to the Fc region of immunoglobulins, inhibiting opsonization and phagocytosis. Therefore, the correct answer is B. Coagulase negative staphylococcus (choice A) does not produce Protein A. Micrococcus (choice C) is a different genus and does not possess Protein A. Choice D is incorrect because Protein A is indeed found in Staphylococcus aureus.

Correct Answer: C

Rationale: The correct answer is C: Endospore. Endospores are dormant, tough, and non-reproductive structures formed by certain bacteria as a response to unfavorable conditions. They help bacteria survive harsh environments such as extreme temperatures, desiccation, and exposure to harmful chemicals. The other choices, Flagella (A), Capsule (B), and Pili (D), do not directly contribute to bacterial survival in adverse conditions. Flagella aid in bacterial movement, capsules provide protection from immune system attacks, and pili are involved in attachment to surfaces or other cells. Endospores are specifically designed for survival during unfavorable conditions, making them the correct choice in this scenario.