The organisms lack secondary pit connections.

In a highly influential 1962 paper, Roger Stanier and C. B. van Niel first established the division of cellular organization into prokaryotes and eukaryotes, negatively defining prokaryotes as those organisms lacking a cell nucleus.

While P450-containing systems are found throughout all kingdoms of life, some organisms lack one or more of these redox domains.

In general, metazoans appear to have SR proteins and unicellular organisms lack SR proteins.

None of the fusing elements would be travelling at high velocity since biological organisms lack any mechanism to do this.

Since these simple organisms lack a complex neural network, computational modeling focuses on the various biochemical pathways of the cells, such as transcription, translation, post-translational modification, and protein-protein interactions.

The burrowing organisms lack a true foot; they have a large pair of jaws and a small radula, comprising a dozen rows of paired teeth.

The organism bears a very superficial resemblance to echinoderms, ctenophores and some of the other Ediacara biota, but lacks enough characters even to ascertain with certainty that it is indeed an animal.

Butterfield implies from the appearance of the fossils that the organisms may have lacked a cuticle: whilst this is also true of the nemerteans, these organisms lack a coelom and are thus unlikely to fossilise.

Polymerase chain reaction-analyses suggested that the organism lacks the DNA genes for polyketide synthesis, the type of toxins associated with most toxic dinoflagellates.