Gases are constantly consumed and produced by cellular and metabolic reactions in most living things, so an efficient system for gas exchange between, ultimately, the interior of the cell(s) and the external environment is required. Small, particularly unicellular organisms, such as bacteria and protozoa, have a high surface-area to volume ratio.
Polyploid. (genetics) an organism or cell having more than twice the haploid number of chromosomes.Of a cell or organism having more than twice the haploid number of chromosomes; a polyploid cell; a polyploid species .Organisms that possess two sets of each chromosome.
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.