When you classify an organism it is important because you need to know the rules
details of the internal and external body structures :)
The most important basis for classifying living things is their genetic similarity.
I think it is the similarities and differences but I could be wrong.
Because, they use them for examining for helpful things
Hydrogen
homologous traits
Skeletal muscles and some fungal hyphae are not divided into cells but have a multinucleate cytoplasm. Some biologists consider unicellular organisms to be acellular
homologous traits
Scientists most likely consider KNOWN characteristics of KNOWN and named organisms when first classifying an unknown organism. They look for similarities and differences between what is known versus unknown. Major differences exclude known categories; strong similarities include the new organism into a known category. This is how scientists continually build a "family tree" of every organism.
phylum
Biologists do not consider crystals of salt to be alive for a few reasons. They do not contain cells or DNA, and they are inorganic since they do not contain hydrogen or carbon.
I think it is the similarities and differences but I could be wrong.
Genetic make up and consistancy in morphological features
you do not provide any choices, so it is impossible to answer your question as stated.
Bacteria is the most important organism because bacteria gets the nutrients from dead plants and animals, and then it provides the nutrients for the grass to be able to grow.
I consider that this information is the electronegativity.
Because, they use them for examining for helpful things
They consider where it lives it's mating patterns and it's fur or coverings....those are on,y some things the consider
Genetic make up and consistancy in morphological features