Artificial selection is
intentional breeding for certain traits.
a process that does not allow a species to reproduce.
a natural process.
when an organism passes on its traits because it is the strongest.

the cell theory states that all living things including animals, as well as plants, are made of cells.

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.