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Mineral Nutrition

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CBSE Gujarat Board Haryana Board

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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.

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

Anaerobic.
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Name the best known symbiotic nitrogen fixing bacterium.

Rhizobium.
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Which pigment is present in the root nodules of legumes ?

Leghaemoglobin.
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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.
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