Question

Which of the following is a free-living nitrogen fixing cyanobacteria?

• A. Cylindrospermum
• B. Nostoc
• C. Rhodospirillum
• D. Both (a) and (b)

Answer 1

Answer: (D)

Both (a) and (b)

D. Both (a) and (b)

Solution : Cylindrospermum and Nostoc both are free living nitrogen fixing cyanobacteria. But Rhodospirillum is a gram negative, spiral shape, facultative anaerobic bacteria.

So the correct answer is "Both (a) and (d)".