Notes: Environment | People, Development and Environment for UGC NET PDF Download

Environment

The environment encompasses all elements surrounding and affecting an organism during its lifetime.

 The term "environment" is derived from the French word "Environ," meaning "our surroundings." It includes natural elements such as air, water, plants, and animals, all of which significantly impact our quality of life on Earth.

Components of Environment

The environment is comprised of two primary components:

Abiotic Components

• Definition: Non-living physical and chemical elements in the environment.
• Examples: Soil, wind, water, sunlight, temperature, minerals, and atmospheric gases.
• Importance: These components provide the essential resources and conditions needed for the survival and growth of living organisms. For example:
  • Soil: Provides nutrients for plant growth.
  • Water: Essential for all living organisms, involved in numerous biological processes.
  • Sunlight: Drives photosynthesis in plants, which is the foundation of most food chains.
  • Temperature: Affects metabolic rates and living conditions for organisms.

Biotic Components

• Definition: Living elements in the environment that interact with each other and with abiotic components.
• Examples: Plants, animals, fungi, bacteria, algae, and microorganisms.
• Importance: These components form the biosphere and are crucial for maintaining ecological balance and supporting life. They engage in processes such as:
  • Photosynthesis: Plants convert sunlight into energy, forming the base of the food chain.
  • Decomposition: Fungi and bacteria break down organic matter, recycling nutrients back into the ecosystem.
  • Predation and Herbivory: Animals consume other organisms, helping control population sizes and maintain balance.

Structure of Environment

The environment is structured into four main segments:

1. Lithosphere

   • Description: The solid, outermost layer of the Earth, including the crust and the upper mantle.
   • Composition: Made up of rocks, minerals, and soil.
   • Coverage: Accounts for about 29% of the Earth's surface.
   • Significance: It supports terrestrial life by providing habitat and resources such as minerals and nutrients. It also includes landforms like mountains, valleys, and plains.

2. Hydrosphere

   • Description: The domain of water, encompassing all forms of water on Earth.
   • Components: Oceans, seas, rivers, lakes, streams, glaciers, groundwater, and atmospheric moisture.
   • Significance: Essential for all living organisms as it regulates climate, supports aquatic life, and is involved in the water cycle. Only a small fraction (less than 1%) of the Earth's water is available as fresh water for human use.

3. Atmosphere

   • Description: The layer of gases surrounding the Earth.
   • Composition: A mixture of nitrogen (78%), oxygen (21%), and other gases like argon, carbon dioxide, and trace gases.
   • Layers of the Atmosphere:
     • Troposphere: The lowest layer, where weather phenomena occur. Temperature decreases with altitude.
     • Stratosphere: Contains the ozone layer, which absorbs harmful UV radiation. Temperature increases with altitude due to ozone absorption.
     • Mesosphere: Characterized by decreasing temperatures and the occurrence of meteors burning up.
     • Thermosphere: Temperature increases with altitude. Contains the ionosphere, which reflects radio waves.
     • Exosphere: The outermost layer, with very thin air. Light gases like helium and hydrogen escape into space from here.

4. Biosphere

   • Description: The zone of life on Earth, where living organisms interact with each other and with their physical environment.
   • Components: Includes all ecosystems, from forests and grasslands to oceans and deserts.
   • Significance: It is the sum of all ecosystems and includes all living beings and their relationships. It is a narrow zone where land (lithosphere), water (hydrosphere), and air (atmosphere) interact to support life.

Interactions Between Components

The components of the environment interact in complex ways to support life on Earth. These interactions include:

• Nutrient Cycles: Elements like carbon, nitrogen, and phosphorus cycle through the lithosphere, hydrosphere, atmosphere, and biosphere, supporting life processes.
• Energy Flow: Sunlight is the primary energy source, driving photosynthesis in plants. Energy flows through ecosystems via food chains and food webs.
• Water Cycle: Water moves through the environment via evaporation, condensation, precipitation, and runoff, supporting life and regulating climate.
• Climate and Weather: Atmospheric conditions influence weather patterns and climate, affecting all living organisms.