Which of the following statements is the best description for the overall reaction that occurs during photosynthesis? a. oxygen + sugar *insert arrow pointing right* carbon dioxide + water b. water + carbon dioxide *insert arrow pointing right* sugar + oxygen c. sugar + oxygen *insert arrow pointing right* water + carbon dioxide d. water + oxygen *insert arrow pointing right* sugar + carbon dioxide

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.