Practice question
Question
A photosynthetic prokaryote contains chlorophyll a, may form colonies surrounded by a gelatinous sheath and sometimes develops heterocysts. Which organism could belong to this group?
Explanation
The features identify cyanobacteria. Cyanobacteria are photosynthetic prokaryotes containing chlorophyll a. Forms such as Nostoc and Anabaena may fix atmospheric nitrogen in specialised cells called heterocysts.