Question

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

• A. phaeophyta
• B. rhodophyta
• C. chlorophyta
• D. bacillariophyta.

Answer 1

The Correct Option is B

The algal class rhodophyceae contains a red pigment (r-phycocrythrin) and a blue pigment (r-phycocynin) in the chromatphores. These pigments can utilize those wavelengths of light (blue-green region of spectrum, i.e., 480-520 nm) that are not absorbed by chlorophyll. This enables red algae to grow at greater depths than other plants (upto 300 ft. below water). In addition to these, chi.-a, chl.- d, carotenes and xanthophylls are present. 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 chi.-a, chi.-c (but not chi.-6), carotenes and xanthophylls. In chlorophyceae colouring pigments are just like higher plants, i.e., Chi.-a, Chi.-6, xanthophylls and carotenes.

So, the correct option is (B): rhodophyta.

Answer 2

The pigment phycoerythrin, which reflects red light and absorbs blue light, is what gives red algae their red color. These pigments enable red algae to photosynthesize and survive at somewhat deeper depths than the majority of other "algae" because blue light can penetrate water to a greater depth than light with longer wavelengths. Because of the chlorophyll and other pigments they contain, certain rhodophytes may seem green or bluish even when they contain very little phycoerythrin. 
Therefore, choice B is the right response.