microbiology chapter 1 test bank

Correct Answer: B

Rationale: The correct answer is B: peak effect. When drug receptors are maximally activated, it means the drug has reached its highest effectiveness, resulting in the peak effect. This occurs when the drug concentration is at its highest level in the body, leading to the maximum response. Threshold level (A) refers to the minimum amount of drug needed to produce a response. Cessation effect (C) is when the drug's effect wears off. Latency time (D) is the time it takes for the drug to start producing an effect. So, the peak effect best describes the scenario where drug receptors are maximally activated.

Correct Answer: C

Rationale: The correct answer is C: Clostridium perfringens. This bacterium is the causative agent of gas gangrene due to its ability to produce gas and toxins in anaerobic conditions. Clostridium tetani causes tetanus, Clostridium botulinum causes botulism, and Bacillus anthracis causes anthrax, not gas gangrene. Clostridium perfringens stands out as the correct choice based on its specific association with gas gangrene and its pathogenic mechanisms.

Correct Answer: B

Rationale: The correct answer is B: peak effect. When drug receptors are maximally activated, it means the drug has reached its highest effectiveness, resulting in the peak effect. This occurs when the drug concentration is at its highest level in the body, leading to the maximum response. Threshold level (A) refers to the minimum amount of drug needed to produce a response. Cessation effect (C) is when the drug's effect wears off. Latency time (D) is the time it takes for the drug to start producing an effect. So, the peak effect best describes the scenario where drug receptors are maximally activated.

Correct Answer: A

Rationale: Rationale: 1. Listeria monocytogenes is a Gram-positive bacterium known for causing foodborne illnesses. 2. Gram-negative bacteria have a different cell wall structure than Gram-positive bacteria, making choice A correct. 3. Choice B is incorrect as Listeria monocytogenes is not encapsulated or sporulating. 4. Choice C is incorrect as Listeria monocytogenes does have a cell wall. 5. Choice D is incorrect as Listeria monocytogenes is indeed a Gram-positive coccobacilli.

Correct Answer: C

Rationale: Step 1: Anthrax causative agent is Bacillus anthracis, which forms spores. Step 2: Spores are highly resistant structures that can survive for a long time. Step 3: These spores can germinate into active bacteria when conditions are favorable. Step 4: The presence of spores in the powder makes it dangerous even long after being mailed. Summary: A: Incorrect - Anthrax does not form a protein capsule. B: Incorrect - Anthrax does not form a polysaccharide capsule. C: Correct - Anthrax forms spores that are highly resistant. D: Incorrect - Anthrax does not form flagella.