Answer:
Cell
Explanation:
Robert Hook is considered to be a pioneers in the field of Micro and cell biology. He was the person who discovered miscroscope that was a source of helping in discovery of several future breakthrough researches in the field of cell biology. During his experiment that lead to the invention of microscope, Hook carefully controlled the height and angle of the microscope by giving it the right illumination sources. He first of all examined the bark of trees where he could see small structures which he named as cell. In subsequent years after the discovery of microscope, scientists were able to learn more about cell and even subcellular organelles with their functions.
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