BIOL 2905 Lecture Notes - Lecture 22: Electromagnetic Spectrum, Opsin, Organism
25 Oct 2017
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Physical nature of light: 2 functions of light, source of energy that directly & indirectly sustains organisms, provides info about physical world that surrounds, ex: algae have chloroplast that harvests energy & uses it to make energy molecules. This excited e-, moving it from ground to excited state. Light energy: light is source of energy. Made accessible to organisms through ability of plants to convert light energy to chemical energy (photosynthesis: light -> sugar) This triggers events like electric signal: for vision, electrical signals are sent to brain. Light captured by eye involves photoreceptors (rods/cones) that line retinal. The eye: photoreceptor contains 1000s of photoreceptor molecules, worms orient themselves so amount of light on ocellus remains equal, organism that have ocelli are: flatworms, insects, arthropods, molluscs. Image forming eyes: compound & single-lens eyes: compound eyes, several units called ommatidia obtain part of visual field, w/light being focused to photoreceptor cells.
