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- A group of yellow, orange, red, or brown
- pigments found in many living organisms,
- particularly in the chloroplasts of plants.
- There are two main types, the carotenes and
- the xanthophylls. Both types are long-chain
- lipids (fats). Some carotenoids act as
- accessory pigments in photosynthesis, and in
- certain algae they are the principal
- light-absorbing pigments functioning more
- efficiently than chlorophyll in low-intensity
- light. Carotenes can also occur in organs
- such as petals, roots and fruits, giving them
- their characteristic colour, as in the yellow
- and orange petals of wallflowers. They are
- also responsible for the autumn colours of
- leaves, persisting longer than the green
- chlorophyll, which masks them during the
- summer.
-