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

Show Answer

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

Show Answer

33. Which are the main source of biofertilisers?

A. Cyanobacteria
B. Bacillus
C. Streptococcus
D. None of these

Show Answer

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

Show Answer

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

Show Answer