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.
1 Polyploid species [species: Used in the classification of living organisms, referring to related organisms capable of interbreeding.] would be represented by 3n, 4n, etc. 2  Polyploids with even numbers of sets of chromosomes are fertile as the chromosomes can form as homologous pairs in meiosis.