Which wavelengths are predominantly absorbed by PSII?

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Multiple Choice

Which wavelengths are predominantly absorbed by PSII?

Light absorption by photosystems is wavelength-specific because the pigments have distinct energy gaps. In PSII, the primary pigment pair (P680) is tuned to red light and is excited most efficiently around 680 nm. This red region is where PSII captures photons to drive the initial steps of the electron transport chain. Among the options, light near 700 nm falls in that red region and best matches the light PSII is designed to use. The other wavelengths lie in blue, green, or far infrared, areas where PSII’s pigments absorb less strongly, so they’re not the dominant absorbed colors for PSII.

Light absorption by photosystems is wavelength-specific because the pigments have distinct energy gaps. In PSII, the primary pigment pair (P680) is tuned to red light and is excited most efficiently around 680 nm. This red region is where PSII captures photons to drive the initial steps of the electron transport chain.

Among the options, light near 700 nm falls in that red region and best matches the light PSII is designed to use. The other wavelengths lie in blue, green, or far infrared, areas where PSII’s pigments absorb less strongly, so they’re not the dominant absorbed colors for PSII.

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