Overview
This lecture explains the concept of the biosphere, its components, extent, and its role as the Earth's life-supporting layer.
Definition and Origin of Biosphere
- The term "biosphere" comes from Greek: "bio" meaning life and "sphera" meaning sphere.
- The biosphere is the sphere or zone where life exists on Earth.
Components of the Biosphere
- The biosphere consists of three components: lithosphere (land), hydrosphere (water), and atmosphere (air).
- Life originated and evolved due to the interaction of the lithosphere, hydrosphere, and atmosphere.
Extent and Characteristics of the Biosphere
- The biosphere extends up to 10 kilometers above sea level and down to more than 8 kilometers below sea level in the ocean.
- The layer containing life is relatively thin; upper atmosphere has little oxygen/low temperatures, ocean depths below 1000 meters are dark and cold.
- The biosphere is compared to an apple peel in relation to the apple's size, indicating its thinness.
Structure and Organization
- The biosphere is Earth's largest biological system.
- It contains smaller functional units called biomes.
Key Terms & Definitions
- Biosphere — The global zone where life exists, comprising land, water, and air.
- Lithosphere — The solid outer layer of Earth (land).
- Hydrosphere — All the water on Earth (lakes, rivers, oceans, etc.).
- Atmosphere — The layer of gases (air) surrounding Earth.
- Biome — A smaller functional unit within the biosphere, defined by climate and organisms.
Action Items / Next Steps
- Review the definitions and characteristics of each biosphere component.
- Be prepared to explain the biosphere and its layers to others.