31) By whom was the concept of survival of the fittest—- Darwin
32) From which is a litmus obtained—-Lichen
33) Who discovered bacteria— A.V.Leeuwen hock
34) What is AIDS virus—-Single-strained RNA
35) From which antibiotic penicillin is extracted—–Fungus
36) What does the virus contain—-Nucleic acid and protein
37) Which are the free-living bacteria—– Azoto bacteria
38) Who was the first creature that released oxygen in our atmosphere—- Cyanobacteria
39) Which gas is generally used to kill the bacteria— Chlorine
40) Which crop can make soil fertile with nitrogenous compound— Pulse