| Answer | Crossword Clue |
|---|---|
| metapsychology | speculation on the origin, structure and function of the mind |
| gene | a specific sequence of nucleotides in DNA or RNA that is located usually on a chromosome and that is the functional unit of inheritance controlling the transmission and expression of one or more traits by specifying the structure of a particular polypeptide and especially a protein or controlling the function of other genetic material |
| homologous | (of organs) Similar in position, structure, and evolutionary origin but not necessarily in function |
| keystone | species of plant or animal that produces a major impact (as by predation) on its ecosystem and is considered essential to maintaining optimum ecosystem function or structure |
