Mineral Nutrition Question 48
48. A free living nitrogen-fixing cyanobacterium which can also form symbiotic association with the water fern Azolla is
[2004]
(a) Tolypothrix
(b) Chlorella
(c) Nostoc
(d) Anabaena
Show Answer
Answer : d
Hints & Solution
(d) The freshwater fern Azolla harbours Anabaena (a blue green alga) in its leaf cavities. Chlorella is simply a green alga. Nostoc is a free living cyanobacteria involved in $N_2$ fixation and so is Tolypothrix.
