Question

The semi permeable membrane surrounding the cytoplasm of a cell

Answer 1

is known as plasmolemma or cell membrane or plasma membrane

Answer 2

The semi permeable membrane surrounding cytoplasm of a cell is called as "cell membrane or plasma membrane".

Explanation:

It is called as semi-permeable membrane because it acts as the watchman of the cells as the content entry and exit of the cell is monitored by this membrane.

It allows only the required material to enter cell and stops or prohibits the entry of unwanted substances. Apart from this it also provides a rigid structure as well as protection to the cell.