Question

Anabaena is member of the phylum

Answer 1

anabaena.. is a cyanobacteria or called eubacteria, which is capable for nitrogen fixation....
In cyanobacteria have some specialised cells called heterocyst , which responsible for nitrogen fixation....
for Your knowledge one more cyanobacteria have heterocyst called nostoc.
This type of bacteria covered mucilaginous sheath

Answer 2

Anabena belongs to --
kingdom-monera/bacteria
Phylum-blue green bacteria