Q66. Antonie van Leeuwenhoek observed several microscopic organisms under
his hand–made microscope. He described them as
(A) Bacteria.
(B) Fungi.
(C) Animalcules.
(D) Bacteriophages.
Antonie van Leeuwenhoek observed several microscopic organisms under his hand-made microscope and described them as animalcules. This is the correct choice for Q66, as historical records confirm he used the term “animalcules” for the bacteria, protozoa, and other microbes he first saw in samples like pond water and dental plaque.
Option Analysis
(A) Bacteria. Leeuwenhoek did observe bacteria, such as in tooth scrapings around 1676, but he did not use the modern term “bacteria,” which entered scientific use over a century later with Otto Friedrich Müller in 1773.
(B) Fungi. He noted mold in 1673, but his key observations of motile microbes in water were not fungi, which are typically non-motile and multicellular at the scales he described.
(C) Animalcules. This matches exactly; Leeuwenhoek called the tiny, moving organisms “animalcules” (Dutch “dierkens” or “little animals”) in letters to the Royal Society starting 1674, describing their shapes, motions, and abundance.
(D) Bacteriophages. These viruses that infect bacteria were discovered in 1915 by Frederick Twort and Félix d’Herelle, long after Leeuwenhoek’s time and beyond his microscope’s resolution.
Antonie van Leeuwenhoek observed microscopic organisms as animalcules using his superior hand-made microscopes, marking a pivotal moment in microbiology history. This discovery, often tested in exams like CSIR NET Life Sciences Q66, highlights his role as the father of microbiology.
Historical Context
A Dutch draper born in 1632, Leeuwenhoek crafted over 500 lenses magnifying up to 500x, far exceeding contemporaries. In 1674, examining pond water, he saw motile “animalcules” – protozoa and bacteria – which he detailed in letters to the Royal Society. These observations refuted spontaneous generation and founded bacteriology and protozoology.
Why “Animalcules”?
Leeuwenhoek chose “animalcules” for their animal-like movement, describing oval shapes with “thin feet” (cilia), spinning motions, and vast numbers making water “seem alive.” He viewed them in rainwater, wells, mouth scrapings, and intestines, estimating thousands per drop.
Exam Relevance for CSIR NET
In Q66, option (C) Animalcules is correct, as sources confirm the term; bacteria (A) fits what they were but not his description, fungi (B) mismatch motility, and bacteriophages (D) are anachronistic. CSIR NET aspirants note this for history of life sciences units.
