Which describes the hydrosphere?

• all of Earth's organisms and the environments in which they live
• a layer of Earth's atmosphere made up primarily of concentrated ozon
• all of the water in Earth's oceans, lakes, seas, rivers, and glaciers, plus the water in the atmosphere

Which best describes the importance of an aquifer?

• it holds uncontaminated ground water for human consumption
• it supplies all water for lakes and rivers
• it provides water for oceans

Which is the best estimate of how much of Earth's saltwater is contained in the given ecosystem?

• aquatic ecosystem, 25%
• swamp ecosystem, 50%
• marine ecosystem, 75%

Which is an area of land that drains to one place?

• river
• aquifer
• watershed
• reservoir

Which best describes the process by which water from the oceans enters the atmosphere?

• infiltration
• precipitation
• evaporation
• condensation

Approximately what percentage of the hydrosphere is represented by the oceans on Earth?

• 30%
• 70%
• 87%
• 97%

Of the 74% of Earth's surface that is coveredin water, which contains the most water?

• lakes
• rivers 
• oceans
• streams

Which is the majority of Earth's freshwater found?

• polar ice caps
• rivers 
• ponds
• lakes

Which is most likely the largest contributor to a decrease in NC water availability?

• evaporation
• global warming
• increase in population
• expansion of agricultural areas

Which best explains why freshwater in in such short supply?

• most of the freshwater is frozen in ice sheets
• most of the freshwater is trapped underground
• mos of the freshwater is cycling in the atmosphere
• most of the freshwater is in the bodies of plants and animals.