Which organelle is like the brain of the cell

The nucleus, this is for Eukaryotic cells.

Nucleus

Explanation:

The nucleus is referred as the brain of the cell because it contains the genetic information necessary to carry out cellular functions.

Inside the nucleus, there is the genetic material called chromosomes, made of DNA that carry the necessary instructions to direct cell activities. Because, DNA carries information necessary for the synthesis of proteins that form tissues and perform various biological functions.  The functions of proteins are to maintain their integrity, defend themselves against external agents, repair damage, control and regulate functions, and others.

Practically, proteins are in charge of almost everything in the organism. And since they are made according to the information encoded in the genetic material inside the nucleus, this organelle is called the brain of the cell.

yes, because even though a theory has a  lot of evidence to support it, it is not always true