Photosynthesis: Pigments and absorption spectra

Xanthophylls (oxygenated carotenoids) are also found in zooxanthellae. Two xanthophylls (diadinoxanthin and diatoxanthin) play an important role in protecting symbiotic algae and coral hosts from excessive light energy. When light energy is sufficient enough to effect pH changes within the photosynthetic apparatus of zooxanthellae, diadinoxanthin is converted to diatoxanthin. This conversion shunts light energy away from photosynthesis. In darkness, the process reverses, and diatoxanthin becomes diadinoxanthin. Note that these xanthophylls both absorb some violet but most strongly blue wavelengths at ~450 - 490nm. See Figure 28.

The action spectrum of photosynthesis relates to the relative ..

and accessory pigments • Pigments and absorption spectra ..

(determining the action spectrum of photosynthesis):

Two techniques for measuring absorption have been used, . theseparate determination of the diffuse reflectance and the diffuse transmittancewith the leaf at a port of an integrating sphere and the direct determination ofthe non-absorbed fraction with the leaf in the sphere. In a cross-check bothmethods yielded the same results for the absorption spectrum.

Chlorophyll and the action spectrum of photosynthesis ..

Determination of efficient (photosynthetically speaking) light sources is important for several reasons. Economy in the costs of maintaining a coral reef aquarium certainly is a concern, but the health of zooxanthellae and hence their animal host should be of primary importance. Aesthetic concerns, such as the promotion of coral coloration through expression of fluorescent proteins and non-fluorescent chromoproteins, are of interest to many.

The photosynthetic action spectrum depends on the type of accessory ..

laboratory determination of action spectra is …

Action Spectrum: The rate of physiological activity (such as oxygen production resulting from photosynthesis) plotted against wavelength of light. See Figure X for an action spectrum of zooxanthellae from a stony coral.

Action spectrum of photosynthesis determined …

The absorption spectrum of a leaf is often thought to contain some clues tothe photosynthetic action spectrum of chlorophyll. Of course, absorption ofphotons is needed for photosynthesis, but the reverse, photosynthesis when thereis absorption, is not necessarily true. As a check on the existence ofabsorption limits we measured spectra for a few different leaves.

the action spectrum for photosynthesis does ..

Determination of Action Spectrum: 1.

A variety of research groups have prepared artificial reaction center molecules. These systems contain a chromophore, such as a porphyrin, covalently linked to one or more electron acceptors, such as fullerenes or quinones, and secondary electron donors. Following the excitation of the chromophore, photoinduced electron transfer generates a primary charge-separated state. Electron transfer chains spatially separate the redox equivalents and reduce electronic coupling, slowing recombination of the charge-separated state to the point that catalysts can use the stored energy for fuel production. Antenna systems, employing a variety of chromophores that absorb light throughout the visible spectrum, have been coupled to artificial reaction centers and have incorporated control and photoprotective processes borrowed from photosynthesis.

02/08/2012 · Bio 113 Absorption Spectrum of Plant Pigment Lab Report

The Photosynthetic Action Spectrum of the ..

PAM Fluorometer: A device capable of monitoring chlorophyll fluorescence, and is capable of calculating the fate of absorbed light energy, either through photosynthesis or two other dissipation pathways (including NPQ: Non-Photochemical Quenching of chlorophyll fluorescence by protective xanthophylls) or NO (dissipation by other pathways, including photoinhibition.) PAM stands for Pulse Amplitude Modulated light intensity. PAR (Photosynthetically Active Radiation): That visible light energy between 400 and 700nm. It is important to note that photosynthesis does not simply stop at wavelengths below 400nm - violet and some ultraviolet wavelengths can promote photosynthesis!

24/12/2017 · Determination of the Absorption Spectrum of a Pigment ..


Attempted determination of dose/response relationships for leaf disc inhibition provided inconclusive data from which to deconvolute an action spectrum.

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