They mustn't. That is, it's not actually required. Prokaryote cells, for example, don't have a nucleus.
A Eukaryotic Cell MUST contain a nucleus. A Prokaryotic Cell MUST NOT have a nucleus. A non-cell would be a virus.
eukaryoic cell
It must have a nucleus the nucleus is the brain of the cell
Plants are eukaryotic, so they must all have nucleus.
This statement is incorrect. Prokaryotic cells do not contain a nucleus. They have their genetic material located in the cytoplasm in a region called the nucleoid. Cells with a nucleus are eukaryotic.
No, it is eukariotic.
Kind of cell that does not have a nucleus?
A cell without a nucleus is called a prokaryotic cell. Prokaryotic cells are simpler in structure compared to eukaryotic cells, which have a defined nucleus that houses the genetic material. Bacteria are examples of organisms that have prokaryotic cells.
ribosomes
The nucleus of the cell contains much of the DNA of the cell, and it regulates the activities of that cell, whatever those activities are.
The nucleus of the cell contains the genome.
To find DNA a scientist must look inside a cell's nucleus.