Class 11 Biology - Chapter Mineral Nutirtion NCERT Solutions | What are the conditions necessary for fi
What are the conditions necessary for fixation of atmospheric nitrogen by Rhizobium. What is their role in N2 -fixation?
Rhizobium is a symbiotic bacteria present in the root nodules of leguminous plants. The basic requirements for Rhizobium to carry out nitrogen fixation are as follows:
(a) Presence of the enzyme nitrogenase
(b) Presence of leg-haemoglobin
(c) Non-haem iron protein, ferrodoxin as the electron-carrier
(d) Constant supply of ATP
(e) Mg2+ions as co-factors
Rhizobium contains the enzyme nitrogenase – a Mo-Fe protein – that helps in the conversion of atmospheric free nitrogen into ammonia.
The reaction is as follows:
N2 + 8e– + 8H+ + 16 ATP→ 2 NH3 + H2 + 16ADP + 16Pi
The Rhizobium bacteria live as aerobes under free-living conditions, but require anaerobic conditions during nitrogen fixation. This is because the enzyme nitrogenase is highly sensitive to molecular oxygen. The nodules contain leg-haemoglobin, which protects nitrogenase from oxygen.
More Questions From Class 11 Biology - Chapter Mineral Nutirtion
- Q:-
What are the steps involved in formation of a root nodule?
- Q:- Explain with examples: macronutrients, micronutrients, beneficial nutrients, toxic elements and essential elements.
- Q:- Why is purification of water and nutrient salts so important in studies involving mineral nutrition using hydroponics?
- Q:- All elements that are present in a plant need not be essential to its survival. Comment.
- Q:- Which of the following statements are true? If false, correct them:
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(b) Every mineral element that is present in a cell is needed by the cell.
(c) Nitrogen as a nutrient element, is highly immobile in the plants.
(d) It is very easy to establish the essentiality of micronutrients because they are required only in trace quantities. - Q:- How are the minerals absorbed by the plants?
- Q:- Name at least five different deficiency symptoms in plants. Describe them and correlate them with the concerned mineral deficiency.
- Q:- Why is that in certain plants deficiency symptoms appear first in younger parts of the plant while in others they do so in mature organs?
- Q:- If a plant shows a symptom which could develop due to deficiency of more than one nutrient, how would you find out experimentally, the real deficient mineral element?
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