Carotenoids pick up nascent oxygen by means of their double bonds and change the same into harmless molecular state.Take a de-starched potted plant of Croton having variegated leaves (leaves with green and non-green patches).
They are of two types, carotenes and xanthophyll’s.Emerson (1957) excitation and fluorescence by chlorophyll, found a sharp reduction in the rate of photosynthesis when monochromatic beam of more than 680 nm was used alone.It is the phenomenon of re-radiation of absorbed energy. The non-green patches do not perform photosynthesis.The curve showing the amount of energy of different wavelengths of light absorbed by a substance is called graphic absorption spectrum. Emerson (1957) found that rate of photosynthesis can be enhanced if monochromatic beams of two different wavelengths (long and short) were applied simultaneously. Test both the leaves for starch.Action spectrum of photosynthesis corresponds closely to absorption spectra of chlorophylls a and b showing that the latter are the main photosynthetic pigments. Chlorophyll a is found in all photosynthetic plants except bacteria. In illuminated leaf only green or chlorophyll bearing Parts appear bluish-black showing that chlorophyll is necessary for photosynthesis. It occurs in all photosynthetic organisms except photosynthetic bacteria. It is studied with the help of spectrophotometer. Chl are primary photosynthetic pigments in plants and other photoautotrophs. After two hours, pluck the un-illuminated leaf and one illuminated leaf. Photosystems The pigments are arranged in funnel shaped photosystems that sit on the thylakoid membranes in the chloroplasts. (v) By their colour, the carotenoids make the flowers and fruits conspicuous to animals for pollination and dispersal. There is some delayed emission or phosphorescence but the same seems to be chemiluminescence or bioluminescence.Before sharing your knowledge on this site, please read the following pages:(ii) Presence of two interconnected pigment systems with some common pigments.Presence of bluish-black patches in illuminated leaf and their absence in darkened leaf clearly indicates that light is necessary for photosynthesis. Chloroplasts contain chlorophyll, a green pigment which absorbs light energy for photosynthesis. This process results in changes of coloration toward the appearance characteristics of ripe fruit.ScienceDirect ® is a registered trademark of Elsevier B.V.Carotenoids have a dual role in cyanobacteria; they are active photosynthetically and provide protection against photooxidation. However, sufficient photosynthesis occurs in the mid part of the light spectrum where carotenoids (carotenes and xanthophyll’s) are active.The first action spectrum was studied by Engelmann (1882) by using a green algae which liberated oxygen according to the rate of photosynthesis in different wavelengths of light. They absorb radiant energy in the mid region of visible spectrum and hand over the same to chlorophyll.There was an error submitting your subscription. The longer light wavelengths have less quantum energy.