Nucleus us an organelles present in eukaryotic organisms and both plant cells and fungal cells are eukaryotes.
Nucleus is housed or enclosed by nuclear membrane.
Nucleus contain the DNA or genetic material of the cell. Nucleus also help to coordinate cellular activities like metabolism, growth,protein synthesis, reproduction e.t.c
Genetic variation is essential for natural selection because natural selection can only increase or decrease frequency of alleles that already exist in the population. Genetic variation is caused by: mutation