SSC CGL - Detailed Guide 2025
Self-Paced Course
Introduction to Environment & Ecology
Reference: NCERT Class 9-12, Lucent GK
1. Definition of Environment
The environment refers to the external conditions, resources, stimuli, etc., with which an organism interacts.
Exam Definition: The Environment is the sum total of all external conditions—biotic (living) and abiotic (non-living)—that affect the life and development of an organism.
2. Components of Environment
Environment is broadly divided into two interdependent components:
| Type | Description | Examples |
|---|---|---|
| Biotic | Living organisms and their interactions | Plants, Animals, Microorganisms, Fungi |
| Abiotic | Non-living physical and chemical elements | Sunlight, Temperature, Soil, Water, Air |
Note: Abiotic factors influence the survival, behavior, and evolution of biotic components.
3. Levels of Organization in Ecology
Ecology studies the interactions between organisms and their environments at various levels of biological hierarchy:
| Level | Description |
|---|---|
| Individual | A single organism (e.g., one tiger) |
| Population | Group of individuals of same species in a given area (e.g., deer herd) |
| Community | All living organisms in a particular area (e.g., forest life) |
| Ecosystem | Interaction between living (biotic) and non-living (abiotic) components in a defined area (e.g., pond ecosystem) |
| Biome | Large regional ecosystem defined by climate and vegetation (e.g., desert, tropical rainforest) |
| Biosphere | Global ecological system combining all living beings and their relationships with the lithosphere, hydrosphere, and atmosphere |
Mnemonic: I → P → C → E → B → B (Individual → Population → Community → Ecosystem → Biome → Biosphere)
4. Branches of Ecology
Ecology is a broad discipline with several branches focusing on specific aspects of interactions and environments.
| Branch | Focus Area |
|---|---|
| Autecology | Study of individual species in relation to its environment (e.g., tiger ecology) |
| Synecology | Study of groups of organisms (communities) and their interactions |
| Agroecology | Study of ecological processes applied to agricultural systems |
| Urban Ecology | Study of ecosystems in urban areas (human-dominated landscapes) |
| Restoration Ecology | Focuses on restoring damaged ecosystems |
| Microbial Ecology | Study of interactions of microorganisms with their environment |
Key: Autecology = Individual-level study; Synecology = Group-level study.
Quick Exam Tips
- • Biotic + Abiotic = Environment
- • Biosphere includes all ecosystems on Earth
- • Autecology & Synecology are the two classical branches of ecology
- • Agroecology helps in developing sustainable agriculture
- • Urban Ecology is vital due to increasing urbanization and climate change impact
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