Who is credited with first observing microorganisms using a microscope?

• A. Antonie van Leeuwenhoek
• B. Joseph Lister
• C. Louis Pasteur
• D. Robert Koch

Answer: (A)

Verified step by step guidance

1. Understand the historical context of microbiology and the development of the microscope.
2. Recall that the first person to observe microorganisms was a pioneer in microscopy during the 17th century.
3. Identify Antonie van Leeuwenhoek as the scientist who improved the microscope and was the first to describe microorganisms, which he called 'animalcules'.
4. Recognize that Joseph Lister, Louis Pasteur, and Robert Koch made significant contributions later, such as antiseptic techniques, germ theory, and microbial culture methods, but did not first observe microorganisms.
5. Conclude that Antonie van Leeuwenhoek is credited with the first observation of microorganisms using a microscope.