what are conditions necessary for fixation of atmospheric nitrogen by rhizome?what os the role in nitrogen fixation?
Answers
Answer:
The conditions necessary for nitrogen fixation by Rhizobium are :
(i) Presence of enzyme nitrogenase.
(ii)A protective mechanism for the enzyme nitrogenase against O2
(iii)A non-heme iron protein-ferrodoxin as an electron carrier.
(iv)The hydrogen donating system (viz, pyruvate, hydrogen, sucrose, glucoseetc).
(v) A constant supply of ATP.
(vi)Presence of thiamine pyrophosphate (TPP), coenzyme-A, inorganic phosphate and Mg++ as co-factors.
(vii)Presence of cobalt and molybdenum,
(viii) A carbon compound for trapping
released ammonia.
In the process of biological nitrogen fixation by free living and symbiotic nitrogen fixers, the dinitrogen molecule is reduced step by step to ammonia (NH3) by the addition of pairs of hydrogen atoms. The pyruvic acid mainly serves as an electron donor but in some cases hydrogen, sucrose, glucose, etc., have also been shown to operate. In leguminous plants, the glucose-6-phosphate molecule probably acts as a substrate for donating hydrogen. The overall process occurs in presence of enzyme nitrogenase, which is active in anaerobic condition. The enzyme nitrogenase consists of two sub-units – a non-heme iron protein (or dinitrogen reductase) and an iron molybdenum protein (Mo-Fe protein or dinitrogenase).
The Fe-protein component reacts with ATP and reduces Mo-Fe protein which then converts N2to ammonia. The ammonia is either directly taken by host or is converted to nitrates with the help of nitrifying bacteria (e.g., Nitrosomonas).
Hope it helps. Plz mark as brainliest.
Answer:
Following conditions are necessary for fixation of Nitrogen by Rhizobium.
Symbiotic relationship between Rhizobium and roots- necessary for the formation of root nodules.
Necessity of a reducing environment
Nitrogenase enzyme – synthesizes ammonia
ATP- is required for the synthesis of ammonia
NAD(P) H2 or FMNH2 is a source of reducing power
Ferredoxin – acts as an electron donor
Keto acids picks up amino group.
nitrate as a substrate – creates reduced availability of nitrate
Role of Rhizobium in N2 fixation:
They fix atmospheric nitrogen in a form that can be used by plants i.e., ammonia, using the nitrogenase enzyme.
Plant, in turn, deliveries bacteria with proteins, carbohydrates and enough oxygen so that they do not disturb the fixation process.
A plant protein – Leghaemoglobin assists in providing oxygen for respiration process while free oxygen concentration level is still low enough to not hinder the nitrogenase activity.