Which scientist is associated with observing microorganisms using a simple microscope in the late 17th century?

• A. Antoni van Leeuwenhoek
• B. Robert Hooke
• C. Louis Pasteur
• D. Francesco Redi

Answer: (A)

Antoni van Leeuwenhoek is the scientist who first observed microorganisms using a simple microscope in the late 17th century. He built powerful single-lens microscopes and used them to examine samples like pond water and dental plaque, revealing bacteria, protozoa, spermatozoa, and other tiny life forms that he described in meticulous drawings and letters to the Royal Society. His work demonstrated that a world of microscopic life exists beyond what the naked eye can see, paving the way for microbiology.

Robert Hooke contributed early microscopy with a compound microscope and is famous for describing plant cells in cork, not microorganisms seen with a simple lens. Louis Pasteur’s pivotal ideas and experiments on germ theory and pasteurization come in the 19th century. Francesco Redi investigated spontaneous generation through macroscopic experiments on meat and maggots, not microscopic observations with a simple microscope.