The kingdom Prokarya.
Unicellular organisms with no nucleus are called prokaryotes; they do not have a kingdom classification, but have two domains: Archaea and Bacteria.
The kingdom Protista does not have a nucleus. It includes organisms like bacteria, which are prokaryotic and lack a membrane-bound nucleus in their cells.
There is no such thing as a bacterium with a nucleus. Single-celled organisms with a nucleus are in the kingdom protista.
A kingdom of one-celled organisms without a nucleus is known as Kingdom Monera or Prokaryotae. These organisms are called prokaryotes and include bacteria and blue-green algae. They lack a membrane-bound nucleus and have a simpler cell structure compared to eukaryotic organisms.
The animal kingdom that lacks a nucleus is the kingdom Monera, which includes bacteria. Bacteria are prokaryotic organisms, meaning they do not have a membrane-bound nucleus like eukaryotic organisms.
Bacteria and Archaea belong to the Kingdom Monera. This kingdom includes prokaryotic organisms that lack a true nucleus.
Monera or Moneran
Cells in organisms that are a part of the kingdom Animalia do have nucleus. Only cells that are prokaryotic cells do not have nucleus.
The kingdom that has only one cell and lacks a nucleus is Monera. Monera includes unicellular prokaryotic organisms such as bacteria, which have a simple cell structure without a membrane-bound nucleus.
Kingdoms that have prokaryotic organisms are Eubacteria and Archaebacteria. Their cells do not have any nucleus and they are simple in structure.
The Kingdom Monera contains prokaryotic organisms: the bacteria and bluegreen algae.
Probably Protista, because there are evidences that suggests they were the first eukaryotes to be developed.