Question

Gene responsible for nitrogen fixation is
A.Nif
B.Nitrogenase
C.Yeast alanine tRNA synthetase
D.RNA synthetase

Answer 1

Hint:We know that molecular nitrogen is converted to ammonia in the process of nitrogen fixation. In the atmosphere, nitrogen is present as molecular dinitrogen which is converted to ammonia by several means.

Complete step by step answer: We know that if the nitrogen fixation is done by living organisms, then it is known as biological nitrogen fixation. Nitrogen-fixing bacteria or cyanobacteria are either free-living or symbiotic in nature.
In leguminous plants, a special structure is formed in the roots for nitrogen fixation. It is called a root nodule. It is formed by the curling of root hair when the plant gets in contact with bacteria Rhizobium. Infection thread is formed and the bacteria invade the root hair. Some bacterias among this are modified into rod-shaped structures called bacteroids. In the final step, a vascular connection is also enabled between the nodule and the host.
Root nodules primarily contain the enzyme Nitrogenase. It catalyzes the conversion of nitrogen to ammonia. This ammonia produced is used for the synthesis of amino acids and finally into proteins by joining several amino acids.
The gene responsible for nodule formation in legumes is known as plant nod genes. Nitrogen fixation occurs under the control of plant nod genes, bacterial nod genes, nif genes, and fixes genes. Note that three bonds between nitrogen atoms are broken and ammonia is formed in this process.
Hence the correct option is A.

Note: Root nodule also contains a special molecule called leghemoglobin. Know that enzyme nitrogenase is highly sensitive to oxygen. It needs anaerobic conditions for its function. Leg hemoglobin acts as an oxygen scavenger and protects the enzyme by providing an anaerobic environment.