When using scientific methods to solve a problem, which of the following is a scientist most likely to do after forming a hypothesis?
a) analyze date
b) draw conclusions
c) state a problem
d) perform an experiment

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.

layer 3 is younger than layer 6.