Cell theory

Avichal

I recently started studying biology because suddenly I started getting curious about this subject. I read about the cell theory which states that all living things have cells.
Is this necessary - that all living things have cells? Can't they have some different structure?

Also these type of questions are repeatedly occurring like - Why this organism has this kind of structure? Why does this membrane exist?...and more. How do I answer such questions?

bobze

For life on earth, part of the definition of "living" we use is typically "has cell/s". Its important to remember that we are defining life here. There are things, like say a virus, which are excluded by this definition. Its very possibly somewhere out there, non-earth life isn't made of cells, but here at home cells are the theme for the most part.

Read about evolution. It is what unifies the main axioms of biology.

cavinmozarmi

Well, keep in mind there are many different types of cells. There are prokaryotes and eukaryotes and so on.