The following paragraph is related to nitrogen fixation. Complete the paragraph by selecting the correct word from those given in the box. You may use a term only once.
Rhizobium, Klebsiella, root nodules, atmospheric, Azotobacter
Certain bacteria are helpful in fixation of atmospheric nitrogen. Bacteria such as _______ and ______ are present in the soil and fix up the elemental nitrogen from the atmosphere. Species of _____________ bacteria are present in ______ of leguminous plants and they increase the nitrogen content of the soil by fixing up _______ nitrogen.

Explanation

To complete the paragraph on nitrogen fixation, we will fill in the blanks with the appropriate words from the given options.

1. **First Blank**: The first blank requires a type of bacteria that helps in nitrogen fixation. From the options provided, "Azotobacter" is a free-living bacterium in the soil that fixes nitrogen.

2. **Second Blank**: The second blank also requires another type of bacteria that is known for nitrogen fixation. "Klebsiella" is another bacteria that can fix nitrogen and is found in the soil.

3. **Third Blank**: The third blank refers to a specific group of bacteria associated with leguminous plants. "Rhizobium" is the correct term here, as it forms symbiotic relationships with the roots of leguminous plants.

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