Why do negative essay results not always mean Michael is absent

I think you mean molecule not Michal so the answer is: the concentration of the molecule may be too low to be detected

Explanation:

linnaeus is the father of taxonomy

explanation:

which is the system of classifying and naming organisms. one of his contributions was the development of a hierarchical system of classification of nature. today, this system includes eight taxa: domain, kingdom, phylum, class, order, family, genus, and species.