Which fractions of the visible spectrum of solar radiations are primarily absorbed by carotenoids of the higher plants : -
A
Blue and green
B
Green and red
C
Red and violet
D
Violet and blue
The answer is D.
Solution
Carotenoids (carotenes and xanthophylls) are yellow, orange and red accessory pigments. They absorb light mainly in the violet-blue part of the spectrum (about 400–500 nm) and reflect yellow-orange light, which gives them their colour. They pass the absorbed energy to chlorophyll a and also protect chlorophyll from photo-oxidation. They do not absorb red light (absorbed by chlorophylls) or green light (reflected by plants). So carotenoids primarily absorb the violet and blue fractions.
ConceptAbsorption by carotenoids
Photosynthesis in Higher Plants in past papers
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