BIOL 1000 Lecture Notes - Lecture 2: Circadian Rhythm, Coevolution, Peppered Moth
Document Summary
What is light: the visible region of the electromagnetic spectrum that humans can detect with their eyes, light is described according to its wavelength but it behaves as particles called photons. How does light interact with matter: reflected off the object, transmitted through the object, absorbed by the object. A photosynthesizing organism could be: green, red, brown, purple, any of the above colours (a-d), only two of the above colours (a-d). Many organisms use light as a source of information. Many organisms exhibit phototaxis (movement in response to light): positive phototaxis - move towards a light stimulus. Dugesia: dugesia (a tiny flatworm) exhibits negative phototaxis. The eye: an organ used to sense light, important for vision, which distinguishes it from the eyespot, vision requires the brain to interpret signals sent to the brain from the eye. Slit-shell snail simple layer of photosensitive cells curved in eyecup.