The first scientist to observe bacteria and other microscopic organisms was: September 2004

Ans. D i.e. Van Leeuwenhoek Leeuwenhoek October 24, 1632 - August 26, 1723 He was a Dutch tradesman and scientist from Delft, Netherlands. He is best known for his work on the improvement of the microscope and for his contributions towards the establishment of microbiology. Using his handcrafted microscopes, he was the first to observe and describe single-celled organisms, which he originally referred to as animalcules, and which are now referred to as microorganisms.