The main objective of this CU is to supply the biological knowledge essential to an environmental engineer, specifically: i) the understanding of the basic processes that attend evolution and functioning of plant and animal species; ii) the understanding of the complex role of biota in the environment and related social-economic aspects, providing the science-base for decision making; iii) the development of biodiversity concepts and of conservation and restoration relevance. The knowledge acquired in this CU is crucial for the areas of ecology, environmental quality, ecotoxicology, environmental health, environmental impact assessment and ecological modelling.