This is the 5923rd most frequent Portuguese word.
biológica
"Biológica" means "biological" in English.
Here, 'biológica' is functioning as an adjective describing the type of research, relating to biology.
A pesquisa biológica revelou novas informações sobre a biodiversidade marinha.
The biological research revealed new information about marine biodiversity.
In this sentence, 'biológica' is describing 'mãe' to specify her connection to Pedro as his mother by birth rather than adoption.
Ela é mãe biológica do Pedro, mas ele foi adotado por outra família.
She is Pedro's biological mother, but he was adopted by another family.
Here, 'biológica' qualifies 'evolução', indicating the process pertaining to biology.