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.
Haploid is the term for a cell or an organism with only one set of chromosomes (n). If this is valid for all cells, the entire organism is regarded as being haploid. A haploÃ¯de cell remains in fact n after replication, but doubles from c to 2c. Each chromosome consists of two chromatids.