Answer:
You either are referring to the fish Chordate, or the animal classification. In the case of the classification it is literally any animal that has developed any sort of dorsal fin, for example some snakes can fall under this classification.
Cells -> Tissues -> Organs -> Organs systems -> Organisms
Paleontologists can identify organisms that may be ancient relatives of those living today. By looking at fossils they can also suggest how these organisms lived together in an ancient habitat. Few organisms become fossilized because the circumstances that an organism has to be in is very specific.
Each cell expresses, or turns on, only a fraction of its genes. The rest of the genes are repressed, or turned off.
The turned on genes are then first transcribed into messenger RNA by the process of Transcription.
Then the mRNA is Translated into protein by the process called Translation.
This is how the specific genes are expressed.
C, it is absorbed by earths surface.
