Biological processes are the processes vital for a living organism to live. Biological processes are made up of any number of chemical reactions or other events that results in a transformation. Regulation of biological processes occurs where any process is modulated in its frequency, rate or extent. Biological processes are regulated by many means; examples include the control of gene expression, protein modification or interaction with a protein or substrate molecule. Physiological process, those processes specifically pertinent to the functioning of integrated living units: cells, tissues, organs, limbs, and organisms. Reproduction Digestion Response to stimulus: a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a stimulus. Interaction between organisms. the processes by which an organism has an observable effect on another organism of the same or different species. Also: cell growth, cellular differentiation, fermentation, fertilisation, germination, tropism, hybridisation, metamorphosis, morphogenesis, photosynthesis, transpiration.