Photosystem II pigments exhibit peak light absorption at a wavelength of___________?
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Answer: A. 680 nm
Explanation
Photosystem II contains specialized reaction center chlorophyll a molecules designated as P680. These pigment molecules absorb light energy most efficiently at a wavelength of 680 nm. This peak absorption drives the initial photochemical splitting of water molecules. Chlorophyll molecules capture photons of light to power the reactions of photosynthesis. Light wavelengths determine the energy level delivered to electrons within pigments. Photosystems work together in chloroplast membranes to convert solar energy into chemical energy.
Understanding light absorption spectra helps agricultural scientists optimize artificial grow lighting. Photosystem II is the first protein complex in the light-dependent reactions of oxygenic photosynthesis. Damage to these reaction centers can impair plant growth under environmental stress conditions. One hundred m is a measurement of distance and bears no relation to light wavelengths. 700 nm is the peak absorption wavelength for Photosystem I reaction centers rather than Photosystem II. 670 nm is a general absorption band for chlorophyll but does not represent the reaction center peak.
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