What I Have Learned 1. a 3. A species is information you've learned from this lesson. Activity: Fill in the blanks the needed word/ phrase to cornplete the 2. When the population of a species begins declining rapidly, the species is said to be occurs when the last member of a species dies. species. 4. The principal causes of deforestation are when its population is so low that it is nearly extinct. farming forest fires, and conversion of agricultural lands to housing projects, and typhoon 5. The effects of deforestation include floods, and depletion of wildlife resources. 6. The major cause of wildlife depletion is the 7. In nutrients are washed away from the land to enrich bodies of water. It causes excessive growth of aquatic plants and algae and results in which eventually die and decompose. The process depletes the oxygen dissolved in water, causing fish and other aquatic organisms to die. 8. is a result of air pollution mostly from factories and motor vehicles.​