_____16. Which of the following is not a source of nitrogen that is available in plants? A. Decaying plant and matter B. Nitrogen oxides released into the atmosphere by burning fossil fuels and o organic matter. C. Synthetic nitrogen containing fertilizers D. Animal waste product. _____17. It is consists of all the organisms that feed at a particular level in a food chain. A. Niche B. Food pyramid C. Trophic level D. Habitat _____18. Secondary consumes belong to ______. A. Fourth trophic level C. Third trophic level B. Second trophic level D. First trophic level _____19. Which is not an abiotic component of the environment? A. Gases B. Light C. Bacteria D. Soil _____20. After the 1992 Rio Summit, it became a buzzword for measuring the health of the planet. And for referring to number of species found there. A. Biodiversity C. Ecological Footprint B. Conservation D. Sustainable development
