Question

What is cell theory? Who propounded it and when?

Answer 1

Hint: Types of cells-
Prokaryotes are small cells that are enclosed by the plasma membrane and have a distinct cell wall that varies in composition depending on the organism. The nucleus and other membrane-bound organelles are absent in prokaryotes. The chromosomal area, which appears as fibrous deposits under the microscope, and the cytoplasm are both found in the protoplasm of a prokaryote.
Eukaryotes are the first complex cells, previously referred to as proto-eukaryotes. These cells grew a mitochondrial symbiont over time and eventually produced a nucleus. This, along with other developments, has created a considerable distinction between the two.

Complete answer:
In \[1855\], Virchow expanded the cell hypothesis by proposing that all cells originate from pre-existing cells. All animals and plants have cells that serve as structural and functional components, and all cells come from pre-existing cells. This is referred to as the Cell Theory. Matthias Schleiden and Theodor Schwann proposed it in \[1839\], and Rudolf Virchow added to it in \[1858\].
The first four statements of cell theory were:
All living organisms are made up of cells, which are the basic building components.
Pre-existing cells are used to create new cells.
All of the cells are the same. Last but not least, cells are the most basic building blocks of life.
In living organisms, cells are the basic units of functionality and structure.

Note:
Modern interpretation of cell theory-
One or more cells make up every known living thing.
By division, all live cells develop from pre-existing cells.
The cell is the primary structural and functional unit in all living organisms.
The activity of an organism is determined by the sum of the activities of individual cells.
Energy flow occurs within cells.