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.
Euploidy is the state of a cell or organism having the same number of each homologous chromosome, possibly excluding the sex-determining chromosomes. For example, most human cells have 2 of each of the 23 homologous monoploid chromosomes, for a total of 46 chromosomes.