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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. Accessory pigments such as carotenes and xanthophylls harvest some green light and pass it on to the photosynthetic process, but enough of the green ...
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.
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] It is related to absorption spectrum in many systems.
The light from the lamp (1.) functions as a detectable change in the plant's environment. As a result, the plant exhibits a reaction of phototropism--directional growth (2.) toward the light stimulus. Auxin distribution controls phototropism. 1. Sunlight strikes the plant from directly above. Auxin (pink dots) encourages growth straight up. 2 ...
Tropisms are usually named for the stimulus involved; for example, a phototropism is a movement to the light source, and an anemotropism is the response and adaptation of plants to the wind. [2] Tropisms occur in three sequential steps. First, there is a sensation to a stimulus. Next, signal transduction occurs. And finally, the directional ...
For example, in green plants, the action spectrum resembles the absorption spectrum for chlorophylls and carotenoids with absorption peaks in violet-blue and red light. In red algae , the action spectrum is blue-green light, which allows these algae to use the blue end of the spectrum to grow in the deeper waters that filter out the longer ...
Typically, plants are responsive to wavelengths of light in the blue, red and far-red regions of the spectrum through the action of several different photosensory systems. The photoreceptors for red and far-red wavelengths are known as phytochromes. There are at least 5 members of the phytochrome family of photoreceptors.
Since the wavelengths compositions change in water with depth: Short (UV, violet) and long (red) wavelengths are lost first, [60] phototaxis and gravitaxis form a ratio-chromatic depth gauge, which allows the larvae to determine their depth by the color of the surrounding water. This has the advantage over a brightness based depth gauge that ...