A function performance of a biosystem is maintained by its negative feedback and redundant pathways. The negative feedback response has been defined as a function-specific homeostasis (FSH) in the laboratory. A FSH non-essential subfunction (FNS) may be in its FNS-specific homeostasis (FNSH). A FSH-specific stress (FSS) disrupting the FSH may also be in its FSS-specific homeostasis (FSSH). A FSS in its FSSH is called successful stress, but a FSS far from its FSSH is just chronic stress. A stress disrupting a FNSH is called an ordinary stress. It was supposed that redundant genes/pathways may be activated partially in a chronic ordinary stress but completely in a successful ordinary stress after studying the deeper networks controlling function networks. Low level laser irradiation or monochromatic light has no direct effects on completely activated redundant genes/pathways, but can modulate partially activated redundant genes/pathways. The redundant hypothesis on redundant pathways is primarily supported by experimental studies, but the one on redundant genes should be further verified.