Question

why is nucleus known as the director of the cell

Answer 1

Because it controls the cell.

Answer 2

The nucleus is called the "director" of the cell, because it has all of the info! DNA is stored in the nucleus, and this is what provides the cell with the instructions for making all of the proteins in our body. Without proteins, we would not be able to survive. The reason is that enzymes, the proteins that help speed up chemical reactions in our bodies, are probably only second to the importance of a semi-permeable membrane. (read:cell membrane) The ability of the cell to be able to choose what enters and leaves, and of enzymes to speed up reactions in our bodies make possible processes that normally could not occur except at temperatures so high they would threaten the well-being of the body, are the reason we are able to maintain our body temperature, blood sugar, etc.