Answer:
Biology is the study of living things and their processes of life. Both Hooke and Van Leeuwenhoek made major, early contributions to biology.
Robert Hooke
Robert Hooke is best known for the discovery of the cell. Using a microscope, Hooke looked at the makeup of a piece of cork. Through the microscope, he saw box-like structures. What he saw would later be known as cell walls. He discovered that these structures were cells, the building blocks of all life.
His discovery and future research contributed greatly to the cell theory.
Anton van Leeuwenhoek
Leeuwenhoek made his discovery after Hooke, but it was still important. He is best known for the discovery of bacteria. Unlike Hooke, Leeuwenhoek did not study plant cells; instead, he focused on protists (like amoebas) and prokaryotes (like bacteria). For his work with unicellular organisms, he is often called the "Father of Microbiology."