Ecosystems & Planet Under Stress

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ACROSS 2   Removal of this species can have disastrous consequences on ecosystems, because they keep the population under check. 4   A local alteration in the atmosphere caused by human activity; mainly an urban problem that is often due to pollutants produced by fuel combustion. 7   A triatomic (O3) form of oxygen that is formed in the stratosphere when sunlight strikes oxygen atoms. This atmospheric ozone helps filter radiation from the sun. 8   The precipitation of sulfuric acid and other acids as rain. The acids form when sulfur dioxide and nitrogen oxides released during the combustion of fossil fuels combine with water and oxygen in the atmosphere. 14   (CFCs) Catalyze the conversion of ozone (O3) into oxygen (O2) without being used up. 18   All ecosystemes on Earth as well as the Earth's crust, waters, and atmosphere on and in which organisms exist; also, the sum of all living matter on Earth. 19   The first level in a food pyramid; consist of organisms that generate the food by photosynthesis; usually consist of plants 20   The aquatic biome consisting of water containing fewer salts than the waters in the marine biome.

DOWN 1   A complex network of feeding interrelations among species in a natural ecosystem; more accurate and more complex depiction of energy flow than a food chain. 3   The northernmost regions of North America and Eurasia, water is frozen most of the time, producing frozen soil or permafrost. 5   The aquatic biome consisting of waters containing 3.5% salt on average; includes the oceans and covers more than 70% of the Earth's surface; 6   The heating that occurs when gases such as carbon dioxide trap heat escaping from the Earth and radiate it back to the surface; so-called because the gases are transparent to sunlight but not to heat and thus act like the glass in a greenhouse. 7   Animals that eat both plants and animals 9   Increase in accumulation of a toxic material (like DDT) as they move up the food chain; also know as biomagnifications. 10   The most complex and diverse biome; found near the equator in South America and Africa; characterized by thin soils, heavy rainfall, and little fluctuation in temperature. 11   Feeding interrelations among species of who feed on whom in a natural ecosystem; very simplistic depiction of energy flow. 12   Characterized by dry conditions and plants and animals that have adapted to those conditions; found in areas where local or global influences block rainfall. 13   The place where an organism lives 15   The higher levels in a food pyramid; consist of primary consumers, which feed on the producers, and secondary consumers, which feed on the primary consumers. 16   The part of the physical environment that consists of all the liquid and solid water at or near the Earth's surface. 17   A large-scale grouping that includes many communities of a similar nature.