Questions: 24 of 68 Concepts completed (i) Multiple Choice Question Alexander Fleming is the scientist that first isolated tetracycline from Streptomyces first observed the antimicrobial effects of penicillin synthesized penicillin through a chemical process in the laboratory developed the antibiotic Salvarsan to treat syphilis

The answer is the second one: first observed the antimicrobial effects of penicillin.

Explanation for each option:

1. First isolated tetracycline from Streptomyces: This is incorrect. Tetracycline was first isolated by Lloyd Conover and his team, not Alexander Fleming.

2. First observed the antimicrobial effects of penicillin: This is correct. Alexander Fleming is famous for discovering the antimicrobial properties of penicillin in 1928 when he observed that a mold, Penicillium notatum, inhibited the growth of bacteria.

3. Synthesized penicillin through a chemical process in the laboratory: This is incorrect. Penicillin was not initially synthesized through a chemical process by Fleming. The mass production and chemical synthesis of penicillin were developed later by other scientists.

4. Developed the antibiotic Salvarsan to treat syphilis: This is incorrect. Salvarsan was developed by Paul Ehrlich and his team, not Alexander Fleming.

In summary, Alexander Fleming is best known for his discovery of the antimicrobial effects of penicillin.