AP BIOLOGY

Detailed explanation-1: -Using single-lensed microscopes of his own design and make, van Leeuwenhoek was the first to observe and to experiment with microbes, which he originally referred to as dierkens, diertgens or diertjes (Dutch for “small animals” [translated into English as animalcules, from Latin animalculum = “tiny animal"]).

Detailed explanation-2: -Leeuwenhoek is universally acknowledged as the father of microbiology. He discovered both protists and bacteria [1]. More than being the first to see this unimagined world of ‘animalcules’, he was the first even to think of looking-certainly, the first with the power to see.

Detailed explanation-3: -In 1674, Leeuwenhoek discovered free living cells in the pond with the help of an improved version of microscope.

Detailed explanation-4: -About 350 years ago, lens grinder and scientist Anton van Leeuwenhoek peered into his microscope at a sample of pond water and discovered a whole world of creatures too small to see with the unaided eye. He thought these creatures were animals the size of molecules, so he termed them “animalcules”.