UPSC CSE Prelims 2007
Plants primarily absorb light in the blue and red regions of the visible spectrum for photosynthesis. Chlorophyll a and b, the main photosynthetic pigments, exhibit strong absorption peaks in these wavelength ranges. Blue light (approximately 430-450 nm) is crucial for vegetative growth, while red light (approximately 640-680 nm) is significant for flowering and fruiting processes. Green light is largely reflected, which accounts for the characteristic green appearance of plants.
Option (A): While violet light is partially absorbed by plants, orange light is absorbed less effectively compared to red light, which is a primary absorption peak for chlorophyll.
Option (C): Indigo and yellow wavelengths are not strongly absorbed by chlorophyll pigments and contribute less significantly to the photosynthetic process compared to blue and red light.
Option (D): Yellow light is not efficiently absorbed by photosynthetic pigments. While violet light is absorbed, its absorption is generally less pronounced than that of blue light.