A student observed an algae with chlorophyll a, b and phycoerythrin, it should belong to

Explanation

(b) : The algal Class Rhodophyceae contains a red pigment (r­phycocrythrin) and a blue pigment (r­phycocynin) in the chromatphores. These pigments can utilize those wavelengths of light (blue­green region of spectrum, i.e., 480­520 nm) that are not absorbed by chlorophyll. This enables red algae to grow at greater depths than other plants (upto 300ft. below water). In addition to these, chl.­a, chl.­ d, carotenes and xanthophylls are present. The student likely observed an alga belonging to Rhodophyta. Rhodophyta, commonly known as red algae, are characterized by the presence of chlorophyll a and chlorophyll d, chlorophyll b, and the red pigment phycoerythrin. The combination of these pigments gives red algae their characteristic reddish color. Among the options provided, only Rhodophyta fits this description. In phaeophyceae chromatophores are yellowish brown in colour possessing xanthophylls in abundance. Bacillariophyceae are called 'diatoms' due to presence of an accessory brown pigment called 'diatomin', other pigments are chl.-a, chl-­c (but not chl.-b), carotenes and xanthophylls. In chlorophyceae colouring pigments are just like higher plants, i.e., Chl.-a, Chl.-b, xanthophylls and carotenes.