Final answer:
Bacteria cannot be classified using the biological definition of a species due to their lack of se-xual reproduction and limited morphological features. Instead, they are classified based on their traits and genetic sequences.
Step-by-step explanation:
Bacteria cannot be classified using the biological definition of a species because they do not reproduce se-xually, making it impossible to classify them based on interbreeding.
In addition, many bacterial species can't be cultured in the lab due to unknown growth requirements or because they are obligate intracellular parasites that need a host cell to grow.
Taxonomy of bacteria is traditionally based on characteristics like shape, staining patterns, and biochemical or physiological differences, and more recently, genetic analysis has become an important tool.