Reflexive locomotion toward (‘positive’) or away (‘negative’) fromlight in phototropic organisms (e.g., phototropic eukaryotes and prokaryotes) along a light gradientor vector. In such organisms, photoaxisis mediated by a pair of very simple eyes or eyespots involving type I sensory rhodopsin photoreceptors.
See Cones and rods, Eurkaryote cell (or organism), Prokaryote cell (or organism)