Question

Why are some nostoc cells green?

Answer 1

Ranging from microscopic to walnut-sized, masses of Nostoc may be found on soil and floating in quiet water. ... Like most blue-green algae, Nostoc contains two pigments, blue phycocyanin and red phycoerythrin, as well as chlorophyll, and has the ability to fix nitrogen in specialized cells called heterocysts.

Answer 2

Many cyanobacteria in high-sulfide conditions photosynthesize as the green and purple sulfur bacteria do. They deposit sulfur in their cells. Yet all can produce oxygen gas. The production of oxygen gas distinguishes the cyanobacteria and the grass-green chloroxybacteria from other photoautotrophic Prokarya.