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The following is a breakdown of the energetics of the photosynthesis process from Photosynthesis by Hall and Rao: [6]. Starting with the solar spectrum falling on a leaf, 47% lost due to photons outside the 400–700 nm active range (chlorophyll uses photons between 400 and 700 nm, extracting the energy of one 700 nm photon from each one)
Chlorophyll a is very important in the energy phase of photosynthesis. Two electrons need to be passed to an electron acceptor for the process of photosynthesis to proceed. [5] Within the reaction centers of both photosystems there are a pair of chlorophyll a molecules that pass electrons on to the transport chain through redox reactions. [20]
Low-nutrient, low-chlorophyll (LNLC) regions are aquatic zones that are low in nutrients (such as nitrogen, phosphorus, or iron) and consequently have low rate of primary production, as indicated by low chlorophyll concentrations. These regions can be described as oligotrophic, and about 75% of the world's oceans encompass LNLC regions.
[21] [22] [23] In this way, the concentration of chlorophyll within a leaf can be estimated. [24] Methods also exist to separate chlorophyll a and chlorophyll b. In diethyl ether, chlorophyll a has approximate absorbance maxima of 430 nm and 662 nm, while chlorophyll b has approximate maxima of 453 nm and 642 nm. [25]
Typical examples include the Leaf Area Index, biomass, chlorophyll concentration in leaves, plant productivity, fractional vegetation cover, accumulated rainfall, etc. Such relations are often derived by correlating space-derived NDVI values with ground-measured values of these variables.
Chlorophyll-a concentration is sometimes used to measure water clarity, especially when suspended sediments and colored dissolved organic matter concentrations are low. Chlorophyll-a concentration is a proxy for phytoplankton biomass, which is one way to quantify how turbid the water is due to biological primary production .
Top: Absorption spectra for chlorophyll-A, chlorophyll-B, and carotenoids extracted in a solution. Bottom: PAR action spectrum (oxygen evolution per incident photon) of an isolated chloroplast. Chlorophyll, the most abundant plant pigment, is most efficient in capturing red and blue light.
Pheophytin a, i.e. chlorophyll a without the Mg 2+ ion.. Pheophytin or phaeophytin is a chemical compound that serves as the first electron carrier intermediate in the electron transfer pathway of Photosystem II (PS II) in plants, and the type II photosynthetic reaction center (RC P870) found in purple bacteria.