Complete Guide to Ecosystem Patterns & Energy Flow
💎 3 GOLDEN FACTS (NEET 2015-24)
⚖️ PYRAMIDS OF NUMBER vs BIOMASS vs ENERGY
| Feature | Number | Biomass | Energy | NEET Examples |
|---|---|---|---|---|
| Shape | Variable (upright/inverted) | Mostly upright | Always upright | 3 Q/yr |
| Units | Individuals | g/m² or g/m³ | kcal/m²/yr | 2 Q/yr |
| Exception | Tree ecosystem (inverted) | Ocean (inverted) | No exceptions | 1 Q/2yr |
🌳 Ecosystem Components
Structural Components:
- Abiotic: Inorganic substances (C, N, P), Organic compounds (proteins, carbs), Climate factors
- Biotic: Producers (plants), Consumers (herbivores, carnivores), Decomposers (bacteria, fungi)
Functional Components:
- Productivity: Rate of biomass production
- Decomposition: Breakdown of organic matter (5 steps: fragmentation, leaching, etc.)
- Energy Flow: Unidirectional flow (10% law)
- Nutrient Cycling: Biogeochemical cycles (C, N, P)
🧠 COMPONENTS Mnemonic
"ABCD": Abiotic, Biotic, Components, Decomposers
Remember all ecosystem components with this simple trick
🌱 Productivity & Decomposition
Productivity Types:
- Primary Productivity: Rate at which energy is converted by producers
- GPP (Gross Primary Productivity): Total photosynthesis
- NPP (Net Primary Productivity): GPP - Respiration (actual biomass)
- Secondary Productivity: Rate of new biomass by consumers
NEET Focus: NPP = GPP - R (appears frequently in PYQs)
Decomposition Process:
- Fragmentation: Breakdown by detritivores (earthworms)
- Leaching: Water-soluble nutrients percolate
- Catabolism: Enzymatic breakdown by bacteria/fungi
- Humification: Dark colored humus formation
- Mineralization: Release of inorganic nutrients
🎯 PYQ Highlights:
NEET 2022: Which ecosystem has highest NPP? Answer: Tropical rainforest
NEET 2020: Correct sequence of decomposition? Answer: Fragmentation → Leaching → Catabolism → Humification → Mineralization
NEET 2018: NPP formula? Answer: GPP - Respiration
⚡ Energy Flow in Ecosystem
Key Concepts:
- 10% Law (Lindeman): Only 10% energy transferred between trophic levels
- Food Chains: Grazing (plants → herbivores) and Detritus (dead matter → decomposers)
- Food Webs: Complex network of interconnected food chains
- Trophic Levels: Producers (1st), Herbivores (2nd), Carnivores (3rd/4th)
Energy Flow Diagram:
Sun → Producers (1%) → Primary Consumers (10%) → Secondary Consumers (1%) → Tertiary Consumers (0.1%)
NEET Must Know: Only 1% of solar energy is captured by plants (PYQ 2019, 2021)
🧠 ENERGY Mnemonic
"SUN 10% LAW": Sun → Unidirectional flow → Nutrients cycle → 10% transfer between levels → Loss as heat → Always upright pyramid → Webs more stable
📊 Ecological Pyramids
Types of Pyramids:
- Pyramid of Number: Count of individuals at each level (can be inverted)
- Pyramid of Biomass: Dry weight at each level (usually upright)
- Pyramid of Energy: Always upright, measured in kcal/m²/yr
Tree ecosystem (few trees support many insects → inverted)
Ocean (phytoplankton < zooplankton → inverted)
🎯 PYQ Highlights:
NEET 2021: Which pyramid is always upright? Answer: Energy pyramid
NEET 2019: Example of inverted pyramid? Answer: Pyramid of biomass in ocean
NEET 2017: Units for energy pyramid? Answer: kcal/m²/yr
Pyramid Comparison Mnemonic:
"NBE": Number (variable), Biomass (mostly upright), Energy (always upright)
📈 NEET 2025 Predictions
High Probability Topics (90% chance):
- 10% energy transfer law with calculations
- Comparison of pyramid types (number vs biomass vs energy)
- Productivity calculations (GPP, NPP, R relationships)
- Decomposition steps sequence
Dark Horse Candidates (Surprise Elements):
- Exceptions in ecological pyramids
- Energy flow in detritus food chain
- Standing crop vs biomass productivity
- Factors affecting decomposition rate
💡 NEET 2025 Master Strategy
- ✅ Memorize all pyramid types with examples (especially exceptions)
- ✅ Practice energy flow calculations (10% law applications)
- ✅ Solve all PYQs on productivity (2015-2024) focusing on NPP/GPP
- ✅ Create comparison charts for different ecosystem components
With these strategies, you'll dominate the 6-8 marks from Ecosystem section in NEET 2025! 🌍🌱
