41. The diagnostic enzyme for nitrogen-fixing organisms is
A. nitrogenase
B. nitrate reductase
C. nitrate oxidase
D. none of these
42. Which of the following fungi on infecting crop roots can improve their uptake of phosphorus and other nutrients?
A. Saccharomyces cerevisiae
B. VA Mycorrhiza
C. Candida torulopsis
D. Aspergillus niger
43. Syntrophism involves
A. exchange of nutrients between two species
B. exchange of nutrients among species
C. no exchange of nutrients between two species
D. no exchange of nutrients among species
44. Assimilative denitrification is done by
A. plants
B. fungi
C. prokaryotes
D. all of these