The main function of siderophores in bacteria is:

Correct Answer: B

Rationale: The correct answer is B: to sequester iron from the environment. Siderophores are molecules produced by bacteria to chelate and acquire iron, an essential nutrient for their growth and survival. By sequestering iron, bacteria can compete with host cells and other microbes for this vital resource. This enhances their ability to thrive and establish infections. Choices A, C, and D are incorrect because siderophores do not directly enhance antibiotic resistance, form capsules, or perform oxidative phosphorylation. These functions are unrelated to the primary role of siderophores in iron acquisition.

Correct Answer: C

Rationale: The correct answer is C because disinfectants are non-selective and can harm a wide range of microbial cells. Disinfectants work by disrupting cell membranes, proteins, and nucleic acids, affecting both harmful and beneficial microorganisms. Choices A and B are incorrect because disinfectants are designed to be potent and non-selective. Choice D is incorrect because the effects of disinfectants are often permanent and irreversible on microbial cells.

Correct Answer: A

Rationale: The correct answer is A: Morphologic features. Bacterial families are classified based on their morphologic features such as shape, size, and arrangement. This classification helps in identifying and studying different bacterial species. Choice B, Geographic features, is incorrect as bacterial classification is not based on their geographic distribution. Choice C, Historical features, is incorrect as it does not play a role in the classification of bacterial families. Choice D, Physiologic features, is also incorrect as physiological characteristics are used for further classification within bacterial families, not as a general characteristic.

Correct Answer: C

Rationale: The correct answer is C because F pili are proteins on the F+ donor cell that are attached to specific receptors on the recipient cell's cell wall. This is essential for the transfer of genetic material during conjugation. Choice A is incorrect because F pili are not made up of nucleotides, but rather proteins. Choice B is incorrect because F pili are not transferred to the recipient cell itself, but they facilitate the transfer of genetic material. Choice D is incorrect because F pili are not part of the recipient cell, but rather part of the donor cell for attachment to the recipient cell.

Correct Answer: A

Rationale: Step-by-step rationale for the correct answer (A: Epstein-Barr virus): 1. Epstein-Barr virus is a member of the Herpesviridae family, known for causing infectious mononucleosis. 2. Members of Herpesviridae have double-stranded DNA genomes and enveloped virions. 3. They establish latent infections in host cells and can reactivate periodically. 4. Poxvirus (B) belongs to the Poxviridae family, not Herpesviridae. 5. SARS (C) is caused by a coronavirus, not a herpesvirus. 6. HIV (D) belongs to the Retroviridae family, not Herpesviridae. Summary: The correct answer is A because Epstein-Barr virus is a member of the Herpesviridae family, exhibiting specific characteristics distinct from the other choices.