Multicellular organisms can be described as an organism which is made up of multiple cells. A unicellular organism is made up of only a single cell. Multicellular organisms are complex organisms as they are made up of more than one cell. Unicellular organisms are simple organisms as they constitute of only a single cell.
Examples of a multicellular organism include humans, elephants, bats, rats, cats etc.
Multicellular organisms are organisms that consist of more than one cell, in contrast to unicellular organisms.[1]
All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- and partially multicellular, like slime molds and social amoebae such as the genus Dictyostelium.[2][3]
Multicellular organisms arise in various ways, for example by cell division or by aggregation of many single cells.[4][3] Colonial organisms are the result of many identical individuals joining together to form a colony. However, it can often be hard to separate colonial protists from true multicellular organisms, because the two concepts are not distinct; colonial protists have been dubbed "pluricellular" rather than "multicellular".[5][6]
The oxygen enters the bloodstream from the alveoli, tiny sacs in the lungs where gas exchange takes place (Figure below). The transfer of oxygen into the blood is through simple diffusion. ... While oxygen moves from the capillaries and into body cells, carbon dioxide moves from the cells into the capillaries.
