Question

Yellowish color of autumn foliage is due to the presence of a type of xanthophyll pigment called as:
A. Lutein
B. Lycopene
C. Fucoxanthin
D. Zeaxanthin

Answer 1

The xanthophylls or phylloxanthins are yellow pigments which occur widely in nature. It forms one of two major divisions of the carotenoid group, the other being carotenes. The xanthophylls are mainly found in the leaves of most green plants. They act to modulate light energy and perhaps serve as a non-photochemical quenching agent which can deal with triplet chlorophyll that is overproduced at high light levels in photosynthesis.

Complete answer:
Option A. Lutein: The lutein is a xanthophyll which is one of the $600$ known naturally occurring carotenoids. Lutein is synthesized by plants, and are found in higher quantities in most green leafy vegetables such as spinach, kale and yellow carrots. Due to the presence of Lutein, autumn foliage is of yellowish color.
Hence option A is the correct answer.
Option B. Lycopene: With antioxidant properties, lycopene is a plant nutrient. This is the pigment that gives characteristic color for red and pink fruits such as tomatoes, watermelons and grapefruit. They give a characteristic red or pink color.
Hence option B is not correct.
Option C. Fucoxanthin: Fucoxanthin is a xanthophyll present as an accessory pigment in the chloroplasts of brown algae and most other heterokonts. This gives them a brown or olive-green color. They are not responsible for the yellowish color of autumn foliage.
Hence option C is not correct.
Option D. Zeaxanthin: A carotenoid that plays a role in protecting the eyes from harmful effects of oxidation and light-induced damage is called zeaxanthin. They are yellow colored pigments found in the center of the macula. Zeaxanthin does not give yellowish color for autumn foliage.
Hence option D is not correct.

Hence, Option A. Lutein is the correct answer.

Note:
Xanthophylls which are found in bodies of animals including the humans, and in dietary animal products are actually derived from plant sources. Looking into an example, the yellow color of chicken egg yolks, fat, and skin comes from ingested xanthophylls which is primarily lutein. And is added to chicken feed for this purpose. In all young leaves and in etiolated leaves, xanthophylls are found.