Unicellular are the organisms which are made of single cell. The single perform all the necessary vital functions of life. Mostly unicellular organisms are prokaryotes such as bacteria, but some are eukaryotes like fungi, and protozoans.
No, mushrooms are multicellular organisms.
They are unicellular organisms.There are eukariyotic and prokariyotic unicellulars.
Unicellulars don't have any vascular system they take food by diffusion. Small animals such as some invertebrates have open circulatory system, larger animals like vertebrate have a closed circulatory system.
Being unicellular means that an organism is made up of a single cell that carries out all necessary functions for life. These cells are capable of going through processes like growth, reproduction, and responding to their environment independently. Examples of unicellular organisms include bacteria and protists.
I think you might want to look at your question again. A unicellular organism doesn't have a job in a cell because they are a cell. Unicellular organisms consist of only one cell (such as an amoeba) and the cell has to carry out all necessary life functions. Multicellular organisms are composed of more than one cell, or more than one type of cell. In this case, cells can become specialized and carry out different functions. There are many individual parts of a cell, such as a nucleus, cell membrane, ribosomes, endoplasmic reticulum, Golgi apparatus, etc. These are found in unicellular organisms and cells of multicellular organisms.