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.
Polygenic inheritance. Polygenic inheritance is a characteristic that is controlled by more than one gene (poly means many). An organismâs final appearance (phenotype) is a result of the interaction between the information held in its genotype and the effect of the environment acting on it during growth and development.