Science Olympiad Dynamic Planet Practice Test

Which term describes the thin layer of gases surrounding the Earth?

1. Hydrosphere

2. Biosphere

3. Atmosphere

4. Geosphere

The correct answer is: Atmosphere

The term that describes the thin layer of gases surrounding the Earth is "atmosphere." The atmosphere is essential for life as it provides the air we breathe, protects us from harmful solar radiation, and regulates temperature through the greenhouse effect. Composed mainly of nitrogen and oxygen, along with trace amounts of other gases, the atmosphere creates the conditions necessary for weather, climate, and various ecological processes. In contrast, the hydrosphere refers specifically to all the water on Earth, including oceans, rivers, and glaciers. The biosphere encompasses all living organisms and their environments, while the geosphere consists of the Earth's solid parts, such as rocks and landforms. Understanding these concepts helps clarify the unique role that the atmosphere plays in sustaining life and influencing Earth's processes.