🌍 Chapter 15: Life on Earth
🌱 Biosphere
- The biosphere is the interrelationship of all plants, animals (including micro-organisms), and the environment around them.
- It is a vital component of our environment.
🧬 Ecology
- Origin of word: Greek words oikos (home) + logy (study) = Study of earth as home for plants, humans, animals, and micro-organisms.
- Definition: Study of the relationship between biotic (living) and abiotic (non-living) components.
- Scientist: German zoologist Ernst Hückel (1869) is known as the father of ecology.
🌿 Ecological Adaptation
- Different ecosystems have different conditions.
- Plants and animals gradually adapt to their environment → called ecological adaptation.
🌎 Biomes
- Definition: A community of plants and animals in a geographical area.
- Examples: Forests 🌳, Deserts 🏜️, Grasslands 🌾, Wetlands 🐸, Mountains 🏔️, Plateaus ⛰️, Estuaries 🌊, Coral Reefs 🐠, Swamps 🐊.
🔗 Ecosystem
- Definition: Interaction of living organisms with land, water, and air in a particular area.
- Features: Clear energy flow and nutritional chains.
🌱 Types of Ecosystem
- Terrestrial Ecosystem 🌳
- Aquatic Ecosystem 🌊
🌳 Terrestrial Ecosystem
- Can be divided into biomes (large communities of plants & animals).
- Factors determining biomes: Precipitation 🌦️, Temperature 🌡️, Humidity 💧, Soil 🪨.
- Examples: Forests, Grasslands, Deserts, Coasts, Tundra, Tidal Estuaries, Coral Reefs, Ocean Floor.
🌊 Aquatic Ecosystem
- Types:
- Marine Ecosystem: Ocean 🌊, Estuaries 🌅, Coral Reefs 🐠
- Freshwater Ecosystem: Lakes 🏞️, Ponds 🌾, Streams 🏞️, Marshes 🐸
⚡ Abiotic Factors
- Non-living factors affecting life:
- Temperature 🌡️
- Rainfall 🌧️
- Sunlight ☀️
- Humidity 💧
- Soil 🪨
- Inorganic elements: CO₂, Water 💦, Nitrogen, Calcium, Phosphorus, Potassium
🐾 Biotic (Biological) Factors
- Includes all living organisms:
- Micro-organisms 🦠
- Birds 🐦
- Mammals 🦁
- Aquatic animals 🐟
- Reptiles 🐍
- Humans 👨👩👧👦
- Interdependence: Divided into Producers, Consumers, Decomposers
🌿 Producers
- Organisms that make their own food via photosynthesis
- Also called: Autotrophic & Primary producers
- Examples: Plants 🌱, Algae 🌊, Grass 🌾
🐛 Consumers
- Depend on producers for food
- Types:
- Primary Consumers: Eat plants 🌿 → Grasshopper, Sheep 🐑, Goat 🐐, Rabbit 🐇
- Secondary Consumers: Eat primary consumers 🥩 → Wolf 🐺, Fox 🦊, Snake 🐍, Bird 🐦
- Tertiary Consumers: Eat primary & secondary consumers 🦁 → Lion, Hawk 🦅, Shark 🦈
⚰️ Decomposers
- Organisms that break down dead matter & recycle nutrients.
- Examples: Fungi 🍄, Bacteria 🦠, Earthworms 🪱
🌎 Functions of Ecosystem
Ecosystem ke main functions:
- Energy Flow ⚡
- Food Chain & Food Web 🍽️
- Biogeochemical Cycles 🔄
⚡ Energy Flow
- Energy flow in an ecosystem is represented by the food/energy pyramid.
- Producers are at the lowest level.
- Primary & secondary consumers come above them.
- 10% Rule:
- Producers make food via photosynthesis 🌱.
- Primary consumers get only 10% of producer’s energy.
- Secondary consumers get 10% of primary consumer’s energy.
- Only 10% energy passes from one trophic level to the next.
🍽️ Food Chain
- Definition: Flow of food energy from one organism to another in an ecosystem.
- Usually consists of 3–5 levels, with energy decreasing at each level.
🐛 Types of Food Chain
- Grazing Food Chain 🌿
- Begins from plants (producers) → herbivores → carnivores (tertiary consumers).
- Energy lost at each level via respiration, excretion, decomposition.
- Detritus Food Chain ♻️
- Based on dead organic matter from the grazing food chain.
- Decomposers recycle nutrients.
💀 Detritus Nutrients
- Consumer group that feeds on dead animals from the grazing food chain.
🔄 Biogeochemical Cycle
- Maintains balance of chemical elements in air, water, soil over millions of years.
- Process: Absorption by organisms → return to environment → cycle repeats
- Driven by: Solar energy ☀️
🌬️ Types of Biogeochemical Cycle
- Gaseous Cycle 🌫️: Source is atmosphere & oceans
- Sedimentary Cycle 🪨: Source is soil, sediments & rocks
🌬️ Oxygen Cycle
- Circulates in air, water, and earth
- Atmospheric oxygen: 21%
- Essential for respiration in humans & animals
🌱 Carbon Cycle
- Carbon is in all living organisms & organic compounds
- Flow: Air ↔ Land ↔ Plants ↔ Animals ↔ Fossil Fuels
- Humans & animals release CO₂, plants absorb CO₂ & release O₂
🌾 Nitrogen Cycle
- Atmosphere: 79% nitrogen
- Fixed by soil bacteria, blue-green algae, lightning & space radiation
- Nitrogen moves through plants → animals → decomposed → returned to soil/air
- De-nitrification: Bacteria convert nitrates back to free nitrogen
⚖️ Situational Balance
- Ecological Balance: Dynamic equilibrium between species & environment
- Stable when number of organisms & food relationships are balanced
❌ Ecological Imbalance
- Occurs when living organisms & physical environment are disturbed
🔹 Causes of Imbalance
- Population Growth 👥 → Pressure on natural resources
- Destruction of Forests 🌳 → Deforestation, floods, droughts
- Technological Progress 🏭 → Pollution & industrial waste
- Lack of Carnivorous Animals 🦁 → Overgrazing → soil erosion
🌱 Importance of Biosphere
- Supports all life 🌎
- Source of food 🍎
- Helps organisms survive, grow & develop 🌿
⚠️ Damage due to Environmental Imbalance
- Natural disasters 🌪️: floods, earthquakes
- Diseases 🦠
- Climatic changes 🌡️
