Adichotomous key works on the principle of asking yes-or-no questions about the organism. to identify it, the answers for that organism are then compared to existing organisms to identify it. prepare a list of four to five questions about each of the organisms listed below to you create your own key. for each question, make sure the answer isn’t the same for all four organisms. for example, does the organism have cells? would be an inappropriate question, because all the organisms have cells. brewer’s yeast (saccharomyces cerevisiae) e. coli bacteria (escherichia coli) green hydra (hydra viridissima) house cat (felis catus)

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.

evidence and logical support is essential for a scientist to do in order to maintain credibility. this is because no one can believe without any logic and without any evidence.hence a scientist can maintain credibility by proving himself and by answering logically so experiments prove very beneficial. logical hypothesis give conclusion which is acceptable. therefore, there are two main factors to maintain credibility by a scientist is evidence and logical support.