When microorganisms enter the circulatory system through the lymphatic drainage and cause an infection, the condition is called:

Correct Answer: C

Rationale: The correct answer is C: microbemia. When microorganisms enter the circulatory system via the lymphatic drainage, the condition is specifically termed microbemia. This term focuses on the presence of microorganisms in the bloodstream. Rationale: 1. Bacteremia (choice A) refers to the presence of bacteria in the bloodstream, not specifically microorganisms as a whole. 2. Septicemia (choice B) is a severe infection causing systemic inflammation due to the presence of pathogens or their toxins in the blood, not limited to microorganisms entering via lymphatic drainage. 3. Viremia (choice D) is the presence of viruses in the bloodstream, not a term used for microorganisms entering through the lymphatic drainage. In summary, the term microbemia accurately describes the scenario of microorganisms entering the circulatory system through lymphatic drainage, making it the correct choice over the other options.

Correct Answer: B

Rationale: The correct answer is B: adolescents. Infectious mononucleosis is commonly caused by the Epstein-Barr virus, which is transmitted through saliva. Adolescents are more likely to engage in activities like kissing and sharing drinks, increasing the chances of virus transmission. Infants have maternal antibodies for protection, young adults may have developed immunity, and the elderly have had more exposure to the virus and may have built immunity over time.

Correct Answer: C

Rationale: The correct answer is C: acetyl-CoA. Acetyl-CoA is the compound that combines with oxaloacetic acid at the beginning of the Krebs cycle to form citric acid. This step is essential for the cycle to proceed, making acetyl-CoA the correct choice. A: Citric acid is formed after acetyl-CoA combines with oxaloacetic acid, so it is a product of the reaction, not the compound that enters the cycle. B: Pyruvic acid is converted to acetyl-CoA in a separate process before entering the Krebs cycle. D: Phosphoglyceraldehyde is not involved in the Krebs cycle; it is a compound in glycolysis.

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.

Correct Answer: B

Rationale: The correct answer is B: 1971. OSHA, the Occupational Safety and Health Administration, was established in 1971 under the Occupational Safety and Health Act signed by President Richard Nixon. This act aimed to ensure safe and healthy working conditions for employees by setting and enforcing standards. Choices A, C, and D are incorrect as OSHA was not established in those years. Option A (1921) is too early, option C (1980) is after OSHA was already established, and option D (1985) is also too late. Therefore, the correct answer is B, 1971, as it aligns with the historical establishment of OSHA.