Bacterial capsules can be stained with one of the following staining methods:

Correct Answer: A

Rationale: The correct answer is A: Neisser. Bacterial capsules can be stained using the Neisser staining method because it specifically targets the capsule, making it visible under a microscope. Neisser staining involves using a combination of acidic and basic dyes to highlight the capsule structure. This method helps differentiate the capsule from the bacterial cell, aiding in the identification and study of capsules. Choices B, C, and D are incorrect because Cleat and Müller staining methods are not commonly used for staining bacterial capsules, and "None of the above" is incorrect as Neisser staining is a valid method for capsule staining.

Correct Answer: A

Rationale: The correct answer is A: BCG vaccine. Step 1: BCG vaccine is specifically designed to protect against tuberculosis, making it the appropriate choice for newborns. Step 2: STI vaccine is for sexually transmitted infections, not tuberculosis. Step 3: EV vaccine is not a recognized vaccine. Step 4: DPT vaccine protects against diphtheria, pertussis, and tetanus, not tuberculosis. In summary, BCG vaccine is the correct choice as it targets tuberculosis specifically, while the other options are designed for different purposes.

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.

Correct Answer: C

Rationale: The correct answer is C: Thick peptidoglycan layer. Gram-positive bacteria have a thick peptidoglycan layer in their cell wall, which retains the crystal violet stain in the Gram staining process, leading to a purple color. This thick layer is a defining characteristic of Gram-positive bacteria. Rationale: A: Thin peptidoglycan layer is incorrect because Gram-positive bacteria have a thick peptidoglycan layer. B: Presence of an outer membrane is incorrect because Gram-positive bacteria lack an outer membrane. D: Presence of lipopolysaccharides is incorrect because lipopolysaccharides are typically found in the outer membrane of Gram-negative bacteria, not Gram-positive bacteria.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Mycobacterium tuberculosis is the causative agent of tuberculosis. 2. Mycobacterium tuberculosis is a slow-growing, acid-fast bacterium. 3. It primarily infects the lungs and can spread to other parts of the body. 4. Bacillus anthracis causes anthrax, Clostridium tetani causes tetanus, and Treponema pallidum causes syphilis. 5. Therefore, choice A, Mycobacterium tuberculosis, is the correct answer for the bacteria responsible for tuberculosis.

Correct Answer: D

Rationale: The correct answer is D: Yersinia enterocolitica. This bacterium can contaminate foods and grow at refrigerator temperatures due to its psychrotrophic nature. Yersinia enterocolitica is known to cause foodborne illnesses even when stored at cold temperatures. Shigella sonnei is a human pathogen transmitted through fecal-oral route, Campylobacter jejuni is typically found in poultry and causes food poisoning, and E. coli can cause foodborne illnesses but does not grow well at refrigerator temperatures.

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: Janssen. In the 16th century, Hans and Zacharias Janssen were a father-and-son team from the Netherlands who are credited with inventing the compound microscope. They constructed a simple tube with lenses at each end, which allowed for magnification of small objects. Their invention significantly contributed to the development of microscopy. Van Leeuwenhoek is known for his contributions to microscopy but did not invent the compound microscope. Semmelweis is known for his work in handwashing and preventing infection. Hooke made significant contributions to microscopy but did not invent the compound microscope.

Correct Answer: D

Rationale: Step 1: Streptococcus pneumoniae is a common cause of community-acquired pneumonia. Step 2: Mycobacterium tuberculosis can lead to tuberculosis, which can manifest as pulmonary tuberculosis. Step 3: Escherichia coli is not typically associated with causing pneumonia. Step 4: Since Streptococcus pneumoniae and Mycobacterium tuberculosis are linked to pneumonia, and Escherichia coli is not, the correct answer is D - All of the above.