⇒ Livings beings are made up of cells & their products

⇒ A cell is a mass of protoplasm having a nucleus 

⇒ Cells are similar in basic structure & metabolism

⇒ Cells are units of structure in body of living organisms

⇒ Cells are units of function in living organisms, ∵ the activities of the organism are some total of the activities of its cells

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The cell theory states that -

> All living cells arise from pre-existing cells by division.

> The cell is the fundamental unit of structure and function in all living organisms.

> The activity of an organism depends on the total activity of independent cells.

> Energy flow occurs within cells.

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