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Class 10 Class 12
What are the conditions necessary for fixation of atmospheric N2 by Rhizobium ? What is their role in N2 fixation.

Conditions for N2 fixation : There are following conditions necessary for N2 fixation :

(1) A strong reducing agent like NADPH : It supplies hydrogen to N2.

(2) ATP as source of energy : It provides energy. For fixation of NH3 molecules, 8 ATP molecules are needed.

(3) The enzyme system : Nitrogenase is necessary for N2 fixation.

(4) Compound for trapping ammonia : Ammonia is very toxic and needs to be trapped in the form of amino acids.

(5) Leghaemoglobin : It is O2 scavenger and maintains anaerobic environment otherwise in the presence of O2 the enzyme nitrogenase is toxicated.

What is Hidden hunger in the case of plants?

Hidden hunger refers to a situation in which a crop needs more of a given nutrient yet has shown no deficiency symptoms. The nutrient content is above the deficiency symptom zone but still considerably needed for optimum crop production

What type of condition is created by leghaemoglobin in the root modules of legumes ?

Anaerobic.

Name the best known symbiotic nitrogen fixing bacterium.

Rhizobium.

How is nitrogenase enzyme protected ?

The nitrogenase enzyme is very sensitive to the molecular oxygen. It requires anaerobic conditions to work. The leg-haemoglobin in the nodule acts as an oxygen scavenger just meainting the anaerobic condition needed by the enzyme.

Which pigment is present in the root nodules of legumes ?

Leghaemoglobin.

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