noun. 1 The red liquid that circulates in the arteries and veins of humans and other vertebrate animals, carrying oxygen to and carbon dioxide from the tissues of the body: drops of blood.More example sentences. Synonyms. 1  Pressure is needed to pump the life giving, oxygen carrying blood around your body. The red liquid that circulates in the arteries and veins of humans and other vertebrate animals, carrying oxygen to and carbon dioxide from the tissues of the body: drops of blood. More example sentences. Synonyms. 1  Pressure is needed to pump the life giving, oxygen carrying blood around your body.
multi-cellular: an organism with 2 or more Cells (multi = many). A multicellular organism is an organism made up of more than one Cell, such as you, me, dogs, cats, birds, bugs, etc. They are complex. They are much much bigger than unicellular organisms and have more body functions. A unicellular organism (also called single cell organism) is an organism made up of only one Cell. Algae, some types of fungus, and bacteria are some examples. These organisms are not very complex, and all their body functions are carried out in that single tiny Cell.
The single-cell regulates all the activity of the organism. Unicellular organisms are small are mostly invisible to the naked eye. There are two general categories of unicellular organisms: prokaryotic and eukaryotic organisms. Prokaryotic unicellular organisms are protists and some fungi. Some of these unicellular prokaryotes live in colonies.