Unicellular beings are characterized because, with a single cell, they are capable of carrying out their vital functions. Remember that prokaryotes and some eukaryotes of the protoctist kingdom (protozoa and algae) and the fungal kingdom (yeasts) are unicellular.
Multicellular beings, on the other hand, are made up of a set of cells that have originated from the egg or zygote cell. From this cell, the others have arisen, all with the same DNA but, through cell differentiation, they have specialized to give rise to the different types of cells existing in the body .
Interactive activity: Tissues, organs and devices or systems.
A tissue is made up of a set of cells that work together to carry out a function in an organism. Different tissues associate with each other to perform even more complex functions, and form the organs. In turn, the bodies that collaborate to perform the same function constitute an apparatus or system.
Interactive activity: The tissues.
The histology is the part of biology that is responsible for the study of tissues. Animal tissues are classified into four types: