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Earth as a System: Energy, Matter and Life - Explain interconnected Earth spheres: biosphere, geosphere, hydrosphere, atmosphere, and cryosphere

Grade 9CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Earth as a System: Earth is considered a closed system for matter but an open system for energy. Energy from the Sun enters the system as radiation, while matter is recycled within the four primary spheres.

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Atmosphere: The gaseous envelope surrounding the Earth. It is composed mainly of Nitrogen (N2≈78%N_2 \approx 78\%) and Oxygen (O2≈21%O_2 \approx 21\%). It regulates temperature and protects the biosphere from UV radiation.

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Geosphere: The solid part of the Earth, including the crust, mantle, and core. It provides the physical foundation for life and contains mineral resources.

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Hydrosphere: Includes all liquid water on Earth, such as oceans, rivers, and groundwater. Approximately 71%71\% of Earth's surface is covered by water.

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Cryosphere: The portion of the Earth's surface where water is in solid form, including glaciers, ice caps, and permafrost. It plays a critical role in Earth's albedo (reflectivity).

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Biosphere: The global ecological system integrating all living beings and their relationships, including their interaction with the elements of the geosphere, hydrosphere, and atmosphere.

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Interconnectivity: Spheres interact through biogeochemical cycles. For example, plants (biosphere) take CO2CO_2 from the atmosphere and water from the geosphere/hydrosphere to produce food.

📐Formulae

6CO2+6H2O+light energy→C6H12O6+6O26CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2

C6H12O6+6O2→6CO2+6H2O+Energy (ATP)C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy (ATP)}

Albedo=Reflected RadiationIncident Radiation\text{Albedo} = \frac{\text{Reflected Radiation}}{\text{Incident Radiation}}

💡Examples

Problem 1:

Describe the interaction between the Geosphere and the Atmosphere during a volcanic eruption.

Solution:

During a volcanic eruption, the Geosphere releases large amounts of particulate matter and gases like SO2SO_2 and CO2CO_2 into the Atmosphere.

Explanation:

The Geosphere (molten rock/magma) crosses the boundary into the Atmosphere, changing the atmospheric composition and potentially cooling the Earth's surface by reflecting solar radiation.

Problem 2:

In the context of the Carbon Cycle, how does carbon move from the Atmosphere to the Biosphere?

Solution:

Through the process of photosynthesis: 6CO2+6H2O→C6H12O6+6O26CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2.

Explanation:

Plants (Biosphere) absorb Carbon Dioxide (CO2CO_2) from the air (Atmosphere) to synthesize glucose, effectively moving carbon from a gaseous state into organic matter.

Problem 3:

Explain how the Cryosphere affects the Hydrosphere in the event of global warming.

Solution:

As temperatures rise, glaciers and ice caps in the Cryosphere melt, contributing to a rise in sea levels within the Hydrosphere.

Explanation:

The phase change of H2OH_2O from solid (ice) to liquid (water) transfers mass from the Cryosphere to the Hydrosphere, altering ocean volume and salinity.