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Class 10 Class 12
Write the various natural methods involved in the replenishment of the soil fertility.

Natural methods involved in the replenishment of the soil ferility are :

(1) Weathering of rocks.

(2) Decomposition of fallen leaves, twigs, dead plants and animals and excreta and their convertion to humus.

(3) Biological nitrogen fixation.

Which pigment is present in the root nodules of legumes ?

Leghaemoglobin.

Name the best known symbiotic nitrogen fixing bacterium.

Rhizobium.

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.

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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