Which of the following is a non–symbiotic nitrogen fixing bacteria?
1.  Rhizobium
2.  Mycorrhiza
3.  Azotobacter
4.  Nitrosomonas

Nitrogen-fixing bacteria converts:
1. $N_2$ $\to$ $N{H}_3$
2. $N{H}_4^{+}$ $\to$ $Nitrates$
3. $N{O}_2$ $\to$ $N{O}_3$
4. $N{O}_3$ $\to$ $N_2$

Select the mismatch:

1. Rhodospirillum - Mycorrhiza

2. Anabaena - Nitrogen fixer

3. Rhizobium - Alfalfa

4. Frankia - Alnus

Study the cycle shown below and select the option which gives correct words for all the four blanks A, B, C and D:
            

Thiobacillus is a group of bacteria helpful in carrying out:

The first stable product of fixation of atmospheric nitrogen in leguminous plants is
1. ${\mathrm{NO}}_2^{-}$
2. ammonia
3. ${\mathrm{NO}}_3^{-}$
4. glutamate

The free-living, anaerobic nitrogen-fixer is
1. Beijerinckia
2. Rhodospirillum
3. Rhizobium
4. Azotobacter

In Glycine max, the product of biological nitrogen fixation is transported from the root nodules to other parts as:

1. Ammonia

2. Glutamate

3. Nitrates

4. Ureides

A nitrogen fixing microbe associated with Azolla in rice fields is
1. Spirulina
2. Anabaena
3. Frankia
4. Tolypothrix

Which of the following bacteria reduces nitrate in soil into nitrogen?
1. Nitrobacter
2. Thiobacillus
3. Nitrococcus
4. Nitrosomonas