Answer:

1. A Dutch father-son team named Hans and Zacharias Janssen invented the first so-called compound microscope in the late 16th century when they discovered that, if they put a lens at the top and bottom of a tube and looked through it, objects on the other end became magnified.

2. The invention of and subsequent refinements of the microscope led to the eventual ability to see cells. ... Later that ,Almost all cells are too small to be seen without a microscope. So microscopes helped scientists to see that all living things are made of cells.

3. Plant cell needs cell wall whereas animal cell do not because the plants need rigid structure so that they can grow up and out . All cells have cell membranes, and the membranes are flexible. So animal cells can have various shapes, but plant cells only have the shapes of their cell walls.