how does the number of cells relate to the functioning of the organism?

The number of cells in an organism is directly related to its functioning because the overall functional capacity of a tissue and the organism depends on the total biomass, which is influenced by cell number. Cells are usually constrained to specific sizes optimal for their functions, so the functional capacity is principally determined by the total number of cells in a tissue. There is an inverse relationship between cell size and cell number, meaning that organisms maintain a trade-off where the total cellular biomass is distributed across cells of varying sizes to support balanced growth and function. In multicellular organisms, cell number affects organ and organism size, with the size and number of cells influencing metabolic capacity, nutrient absorption, and biosynthetic functions. Disorders in cell size or number can indicate disease or affect organismal function. Different cell types have specialized sizes suited to their roles, such as neurons for signal transmission or muscle cells for movement. In summary, the number of cells, combined with their size, regulates the organism's growth, functional capacity, and health by determining total tissue biomass and specialized functions carried out by different cell types.