ATI RN
microbiology an evolving science test bank Questions
Question 1 of 5
The cell envelope in gram positive bacteria is:
Correct Answer: A
Rationale: The correct answer is A: Two-layer. In gram-positive bacteria, the cell envelope consists of two layers: the thick peptidoglycan layer and the cytoplasmic membrane. The peptidoglycan layer is much thicker compared to gram-negative bacteria, providing structural support and protection. The cytoplasmic membrane is located beneath the peptidoglycan layer and serves as a barrier between the cytoplasm and the external environment. The other choices are incorrect because gram-positive bacteria do have a cell envelope, it is composed of two layers, not three layers, and it is not just a single layer. Choice D is incorrect as it states that there is no cell envelope in gram-positive bacteria, which is not true.
Question 2 of 5
Protein A is located in the cell wall of:
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.
Question 3 of 5
Specify the most commonly used parameters for autoclaving sterilization:
Correct Answer: A
Rationale: The correct answer is A because it specifies the commonly used parameters for autoclaving sterilization: 1.0 atm pressure, 120º C temperature, and 15-20 minutes duration. This combination ensures effective sterilization by providing the necessary heat and pressure for killing microorganisms. Rationale: 1. Pressure of 1.0 atm: Standard atmospheric pressure commonly used in autoclaving. 2. Temperature of 120º C: Optimal temperature for sterilization without causing damage to heat-sensitive materials. 3. Duration of 15-20 minutes: Time required for heat and pressure to penetrate and kill microorganisms effectively. Summary of Incorrect Choices: B: Incorrect temperature and duration, too high and long, may damage materials. C: Incorrect pressure and temperature, higher pressure and temperature not commonly used. D: Incorrect temperature, too high, can damage materials, and duration is longer than necessary.
Question 4 of 5
What type of immunity is responsible for the agglutination of viruses:
Correct Answer: B
Rationale: The correct answer is B: Humoral immunity. Humoral immunity involves the production of antibodies by B cells that can bind to antigens on viruses, leading to their agglutination. This process prevents the spread of the virus in the body. Passive immunity (A) involves receiving pre-formed antibodies, not the production of antibodies. Cell-mediated immunity (C) involves the activation of T cells, not the direct agglutination of viruses. Non-specific immunity (D) refers to general defense mechanisms like inflammation and fever, not targeted agglutination of viruses.
Question 5 of 5
Agglutination reaction is one of the following:
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.