Agriculture Microbiology MCQ tribhuvan University 2

11. Dissolution of rocks is due to
a. Carbonic acid b. Organic acid c. freezing and thawing d. all of the above
12. In which depth in a garden soil does the maximum number of microorganisms per gram occur?
a. at a depth of 3-8 cm. b. at a depth of 1-3 cm c. at a depth of 8-12 cm d. at a depth of 12-25 cm
13. compound responsible for the distinctive “earthy” odor of soil is
a. Phytoalexins b. root exudates c. cellulose d. Geosmin
14. ………… is a common denitrifying bacteria?
a. Pseudomonas b. Nitrobacter c.frankia d. azospirillum
15. dissimilatory sulfur- reducing bacteria……………
a. can reduce elemental sulfur to sulfide but are unable to reduce sulfate to sulfide
b. cant reduce elemental sulfur to sulfide but can reduce sulfate to sulfide
c. can reduce both elemental sulfur and sulfate to sulfide
d. cant reduce both elemental sulfur and sulfate
16. Desulfuromonas is ………………..
a. obligate anaerobes b. sulfate reducing bacteria c. both of above d. facultative aerobe
17. Formation of “infection thread” in certain root hairs is due to
a. Rhizobium bacteria b. pathogenic bacteria c. pathogenic fungi
18. Organisms involved in non symbiotic nitrogen fixations are the species of;
a. Spp of Azotobacter b.Cyanobacteria c. Clostridium Pasteurianum d. all of the above
19. The amount of nitrogen fixed by the non symbiotic process ranges between
a. 20-50lb/acre annually b 50-100 lb/ acre annually c. >200 lb/acre annually
20. Nitrogenase enzyme complex contains component I an II……….
a. Nitrogenase and Nitrogenase reductase b. MoFe protein and Fe protein
c. Both of the above d. None of the above