Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

Who was the scientist that first observed and described bacteria?

1. Andrea Vesalius

2. Anton van Leeuwenhoek

3. Robert Hooke

4. Carl Von Linnaeus

The correct answer is: Anton van Leeuwenhoek

The scientist who first observed and described bacteria was Anton van Leeuwenhoek. He is often referred to as the "father of microbiology," having made significant contributions to the field in the late 17th century. Using his own handcrafted microscopes, van Leeuwenhoek was able to observe single-celled organisms, which he famously called "animalcules." His meticulous observations laid the foundation for the field of microbiology and provided some of the earliest evidence of the existence of microorganisms, including bacteria. While other scientists, like Robert Hooke, made important contributions to the understanding of cellular structure (most notably the cork cells he described), they did not specifically observe bacteria in the way van Leeuwenhoek did. Andrea Vesalius is known for his work in anatomy, and Carl Von Linnaeus is celebrated for developing the system of taxonomy that classifies living organisms, but neither was involved in the discovery or description of bacteria as a separate organism. Thus, van Leeuwenhoek's pioneering work in using microscopes to observe these microscopic life forms uniquely qualifies him as the scientist who first described bacteria.