This teacher's guide contains parts three and four of the four-part first year Portland Project, a three-year secondary integrated science curriculum sequence. Part three of the guide deals with topics such as the cell, reproduction, embryology, genetics, genetic diseases, genetics and change, populations, effects of density on populations, ecosystems, and communities. Part four deals with related topics. After studying about ecosystems in general terms, the emphasis is shifted to studying about the harmful effects of human activities in upsetting the balance of ecosystems. Topics include water pollution, air quality, and effects of air pollution. In both parts, laboratory exercises are suggested and lengthy lists of supplementary materials are included. Notes for the teacher, examples of data, and problem calculations are included. (SL)