BIOL 341 Lecture Notes - Lecture 9: Violaxanthin, Cytosol, C3 Carbon Fixation
24 Feb 2017
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Document Summary
Light that is perpendicular to the leaf versus at an angle : light levels are reduced by the cosine of the angle . Photon irradiance: number of quanta striking the leaf (mol m-2s-1) Photosynthetically active irradiation (par): irradiance consisting of wavelengths between 400-700nm. Light compensation point: rate at which photosynthetic co2 uptake = co2 release (release due to mitochondria respiration: respiration rates lower in shade plants thus they reach compensation point sooner (have an overall lower compensation point) Allows shaded plants to utilize par at very low levels (ie. levels found in shaded environments) Maximum quantum yield: slope of linear portion of curve (ratio of # co2 assimilated/ # photons: quantum yield: with photorespiration. Varies with temp and [co2] due to te(cid:373)p"s effe(cid:272)ts o(cid:374) ru(cid:271)is(cid:272)o"s oxygenase:carboxylase activity (discussed more later) Acclimation: plants have sufficient plasticity to survive in sun and shade: each leaf can have certain biochemical & morphological characteristics depending on leaf-specific light conditions.
