It is recommended that children eat foods high in calcium and iron as a way to reduce the accumulation of lead in their cells and enzymes. Explain why this is a scientifically valid recommendation.

a. the production of carbon dioxide through the process of photosynthesis

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.