1. In 1665, Robert Hooke, an English scientist, published his book Micrographia, in which he described that pieces of cork viewed under a microscope presented small cavities, similar to pores and filled with air.
Based on knowledge discovered later on, what do you think those cavities were composed of? What is the historical importance of this observation?
2. What are the two main groups into which cells are classified?
3. Do the cells of bacteria have a nucleus?
4. Are any bacteria made of more than one cell?