Search results
Results From The WOW.Com Content Network
PAR as described with PPF does not distinguish between different wavelengths between 400 and 700 nm, and assumes that wavelengths outside this range have zero photosynthetic action. If the exact spectrum of the light is known, the photosynthetic photon flux density (PPFD) values in μmol⋅s −1 ⋅m −2) can be modified by applying different ...
Phototropism in Solanum lycopersicum. In biology, phototropism is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light contain a hormone called auxin that reacts when phototropism ...
Based on studies with action spectra, mutants and molecular analyses, it has been determined that higher plants contain at least 4, and probably 5, different blue light photoreceptors. Cryptochromes were the first blue light receptors to be isolated and characterized from any organism, and are responsible for the blue light reactions in ...
Absorbance spectra of free chlorophyll a (blue) and b (red) in a solvent. The action spectra of chlorophyll molecules are slightly modified in vivo depending on specific pigment-protein interactions. An action spectrum is a graph of the rate of biological effectiveness plotted against wavelength of light. [1]
This mismatch between absorption spectra and photochemical action plots has by now been observed in a wide array of photoreactive systems. [41] [42] [43] A prominent example is the photoinduced [2+2] cycloaddition of the stilbene derivative, styrypyrene, which exhibited an 80 nm discrepancy between the action plot and absorption spectrum. [33]
One study found that phototropins on the plasma membrane play a role in phototropism, leaf flattening, stomatal opening, and chloroplast movements, while phototropins on the chloroplasts only partially affected stomatal opening and chloroplast movement, [16] suggesting that the location of the protein in the cell may also play a role in its ...
Oat phytochrome absorption spectrum (Devlin, 1969). Phytochromes are a class of photoreceptor proteins found in plants, bacteria and fungi.They respond to light in the red and far-red regions of the visible spectrum and can be classed as either Type I, which are activated by far-red light, or Type II that are activated by red light. [2]
The visible-light part of the action spectrum was found to have a peak in the red-light region, suggesting that chlorophylls act as photoreceptors of photoinhibition. In the 1980s, photoinhibition became a popular topic in photosynthesis research, and the concept of a damaging reaction counteracted by a repair process was re-invented.