The antigen receptors on the surface of B-lymphocytes are made by proteins:

Correct Answer: A

Rationale: The correct answer is A: TRUE. B-lymphocyte antigen receptors are made by proteins called immunoglobulins. These proteins are essential for recognizing and binding to specific antigens. They play a crucial role in the immune response. Choice B is incorrect because B-lymphocyte antigen receptors are indeed made by proteins. Choice C is incorrect as well because in this case, the correct answer is that the receptors are made by proteins. Choice D is also incorrect as the receptors are made by proteins.

Correct Answer: D

Rationale: The correct answer is D: Imipenem. Imipenem is a carbapenem antibiotic effective against multiple-resistant microorganisms due to its broad spectrum and resistance to beta-lactamases. It is often used as a last resort for severe infections. Ampicillin (A) and Penicillin (B) are both beta-lactam antibiotics that are less effective against multiple-resistant microorganisms due to widespread resistance mechanisms. Augmentin (C) is a combination of amoxicillin and clavulanic acid, which may have limited efficacy against certain resistant strains but is not as effective as imipenem for treating infections caused by multiple-resistant microorganisms.

Correct Answer: C

Rationale: The correct answer is C because cultural characteristics of bacteria refer to their growth patterns on different culture media, including liquid and solid agars. Bacteria exhibit unique growth patterns that can be observed and studied on these media. Choice A is incorrect as it refers to isolation techniques, not cultural characteristics. Choice B is incorrect as it describes metabolic activities, not cultural characteristics. Choice D is incorrect as it dismisses the essential aspect of bacterial growth on culture media.

Correct Answer: A

Rationale: The correct answer is A because Legionellae are typically found in natural water sources such as lakes, rivers, and soil. Legionellae thrive in aquatic environments and can also be present in mud. Choice B is incorrect as Legionellae are not limited to infected humans but are also found in the natural environment. Choice C is incorrect as Legionellae are not primarily associated with infected animals. Choice D is incorrect as Legionellae do have natural reservoirs in water and soil.

Correct Answer: A

Rationale: The correct answer is A: Blood agar. Streptococcus pneumoniae is a fastidious bacterium that requires enriched media for growth. Blood agar provides the necessary nutrients and growth factors for the cultivation of S. pneumoniae, such as blood proteins and hemin. MacConkey agar (B) is selective for gram-negative bacteria and would not support the growth of S. pneumoniae. Peptone water (C) is a liquid medium that lacks the necessary nutrients for the growth of S. pneumoniae. Choice D is incorrect as blood agar is a suitable medium for cultivating S. pneumoniae.