Physiology (grch. phýsis = nature and lógos = theory) is the study of the fundamentals of life, especially the life processes and functions in an organism. In detail these are the biophysical life processes in the cells, tissues and organs of all living beings in the interaction of all physical, chemical and biochemical processes. Plant physiology is the study of the life processes of plants with the central life process of photosynthesis. Further aspects are growth processes, differentiation of organs, reactions to environmental stimuli, substance transport and the communication between cells, tissues and organs. In the case of the vine, the term physiological ripeness, which is important during the grape harvest, is used. In contrast, morphology (grch. morphé = shape, form) is the study of forms and characteristics, and phenology (grch. phaíno = I appear) is the study of seasonal manifestations or the development cycle in organisms. See also a list of relevant keywords under vine.