The statement that all cells have a nucleus is false.
While many cells, particularly those in plants and animals, do contain a nucleus that houses their genetic material, there are also types of cells that do not. For instance, prokaryotic cells, such as bacteria, lack a nucleus entirely. Instead of a nucleus, their genetic material is located in a region called the nucleoid.
In summary, while a nucleus is a key feature of eukaryotic cells, it is not present in all cells. So the claim that all cells have a nucleus is incorrect.