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.
Gametes (sperm and ova) are haploid cells. The haploid gametes produced by most organisms combine to form a zygote with n pairs of chromosomes, i.e. 2 n chromosomes in total. The chromosomes in each pair, one of which comes from the sperm and one from the egg, are said to be homologous.Cells and organisms with pairs of homologous chromosomes are called diploid.or example, most animals are diploid and produce haploid gametes. During meiosis, sex cell precursors have their number of chromosomes halved by randomly choosing one member of each pair of chromosomes, resulting in haploid gametes.