The word equation for photosynthesis is: Light [IMAGE]Carbon Dioxide + Water Glucose + Oxygen Chlorophyll Although most of the glucose produced is converted into insoluble starch for storage in the stem, leaves or roots, some is used immediately by the plant to provide via respiration....
This desire to discover new ways of producing clean energy has lead scientists at Stanford University and other universities to discover a way to harness the electricity produced during the process of photosynthesis.
This article will examine photosynthetic efficiencies of various LEDs. Specifically, six light sources were tested for photosynthetic responses by zooxanthellae found in the stony coral (most likely of Clade C15.) The light sources include a black light (mostly UV-A produced by a fluorescent lamp), and LEDs radiating energy at peaks of 400nm (UV-A/violet), a 418nm LED (producing mostly violet with a small amount of UV-A), a blue/white LED combination peaking at white light with a peak 443nm and 457nm, a 'white' LED with a blue peak at 443nm, and red LEDs producing maximal light at 631nm and 657nm. All tests were performed when light intensity was at sub-saturating levels. Evidence suggests absorption by carotenoids is responsible for lessened photosynthetic efficiencies at 450 nm and 470 nm.
There are two broad classifications of carotenoids: carotenes and xanthophylls, said Premkumar. The difference between the two groups is chemical: xanthophylls contain oxygen, while carotenes are hydrocarbons and do not contain oxygen. Also, the two absorb different wavelengths of light during a plant’s photosynthesis process, so xanthophylls are more yellow while carotenes are orange.
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.
The radiometric power of a photon matters not in photosynthesis - a blue photon (with high radiometric power) will drive photosynthesis just as well as a photon of lesser energy (say, a red photon.) So, it would seem that the issue is settled. It is not. The adage 'a photon is a photon' is true when discussing light production by various light sources, but it is not correct when considering how different light wavelengths (or bandwidths) promote 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.
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!
Photopigments: Organic substances responsible for collecting light energy and hence the promotion of photosynthesis. Common photopigments in zooxanthellae are chlorophyll , chlorophyll peridinin, and -carotene.
State Transition: A redistribution of collected light energy from one photosystem to another, thus allowing photosynthesis to occur in an efficient manner. Redistribution is known to occur in some zooxanthellae clades, usually from Photosystem II to Photosystem I, and prevents a damaging traffic jam of electrons. State Transition is also known as 'spill-over.'
Carotenoids are a class of phytonutrients ("plant chemicals") and are found in the cells of a wide variety of plants, algae and bacteria. They help plants absorb light energy for use in photosynthesis. They also have an important antioxidant function of deactivating free radicals — single oxygen atoms that can damage cells by reacting with other molecules, according to the .
Yield: The amount of product produced (such as photosynthesis) by the interaction of two substances (such as light and chlorophyll), generally expressed as a percentage. Zooxanthellae typically have a Yield of 0.30 - 0.40, while terrestrial plants' Yields are much higher (~0.80.)
This process is also affected by the temperature surrounding the plant (the species of plant we experimented with, pond weed, photosynthesised best at around 20 degrees centigrade.) Light, temperature & CO2 are known as limiting factors, and each is as important as the next in photosynthes...