29. Which of the following species of different genera of bacteria are not capable of transforming nitrate to nitrogen?
A.Achromobacter
B.Agrobacterium
C.Alcaligenes
D.None of these

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30. Some microorganisms have the ability to increase the nitrogen content of soils, are called as
A.nitrogen fixation
B.denitrification
C.nitrification
D.all of these

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31.  Nitrogen fixation
A.changes the free nitrogen (N2) to a form usable by plants
B.especially changes nitrogen compounds, mostly amines such as NH2
C.both (a) and (b)
D.fix the free nitrogen (N2) by which it should not be usable by plants

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32. For rapid decomposition by microbes, the substrate should have a C/N ratio of
A.10-20
B.20-30
C.30-40
D.60-80

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33. Which are the main source of biofertilisers?
A.Cyanobacteria
B.Bacillus
C.Streptococcus
D.None of these

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34. The organisms responsible for the characteristic musty or earth odor of a freshly plowed field is/are
A.Nocardia
B.Streptomyces
C.Micromonospora
D.all of these

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35.  Denitrification is
A.reduction of nitrate (NO3-) to nitrogen gas
B.reduction of nitrate to organic nitrogen compounds
C.both (a) and (b)
D.changing of atmospheric nitrogen (N2) to nitrogen compounds

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