Bacteria and yeast are unicellular organism …

Characteristics of Kingdom Monera:

(i) Kingdom Monera are one-celled without an organized nucleus. Examples: bacteria and blue-green "algae."

(ii) They are found in almost every imaginable habitat; in air, soil, and water and in extreme temperatures and harsh chemical environments.

(iii) There are no membrane bound "organelles".

(iv) Reproduction by asexual method.

(v) Monerans show either autotrophic or heterotrophic nutrition.

(vi) Cell wall may be present or absent.

Characteristics of Kingdom Protista:

1. This group includes many kinds of unicellular eukaryotic organisms such as unicellular algae, protozoans and unicellular fungi. 
2. They are found where there is moisture.
3. They are single celled, but many live in a colonial setting (more or less independently). 
4. Many are unicellular, but some are multicellular (Algae and fungus-like protists).
5.  Some can live in very harsh environments.
6. Reproduction can be sexual (conjugation), asexual (binary fission), or a combination of both.
7. Some of these organisms use appendages, such as hair-like cilia (e.g. Paramecium) or whip-like flagellum (e.g. Euglena).
8. Their mode of nutrition can be autotrophic or heterotrophic.