Question

Which of the following gene clusters in bacteria is responsible for nitrogen fixation?

• A. nod, nif, fix
• B. nod, nd, nfx
• C. nod, nix, nfx
• D. ndx, nif, fix
• E. ndx, nif, nix

Answer 1

Answer: (A)

nod, nif, fix

The nod, nif and fix gene clusters in bacteria are responsible for nitrogen fixation. The nodulation genes are the nod genes. These genes are responsible for the development of nodules. The nif and fix genes are responsible for nitrogen fixation activity. In most of the nitrogen-fixing bacteria, there are a number of nod, nif and fix genes found clustered together in various groups.

So, the correct answer is option A.