Cyanobacteria are unicellular prokaryotic organisms. Besides, some primitive cellular cell organelles, they have photosynthetic lamellae where photosynthetic pigments are present. There are chlorophyll-a c, phycocyanin and phycoerythrih. These coloured pigments impart typical blue green colour to the bacteria and enable them to manufacture food for themselves and aquatic animals, Green plants are multi cellular organisms capable of making food by using carbon dioxide, water and light energy in special cell organelles called chloroplast. , So, bacteria and green plants make food for living organisms on earth.