GEF

Unit 4   |  The Global Ecosystem 102 ASSESS YOUR UNDERSTANDING Select the best answer from the choices provided. 1. Species, such as sea otters, that have a huge impact on their ecosystem if removed are known as: a. Keystone species b. Biocentric c. Environmental species d. Endangered species 2. The hydrosphere refers to which Earth system? a. Water b. Air (gasses) c. Land (rock) d. Life 3. Which of the following “spheres” is the major source of our fossil fuels? a. Lithosphere b. Hydrosphere c. Geosphere d. Biosphere 4. Which of these cycles is most closely related to the greenhouse effect? a. Carbon b. Nitrogen c. Rock d. Water 5. Bacteria is an essential component of which Earth system? a. Water cycle b. Carbon cycle c. Nitrogen cycle d. Rock cycle