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Class 11 Geography Chapter 16 – Biodiversity and Conservation Notes in English | CBSE Exam Ready

 

🌱 Chapter 16 – Biodiversity and Conservation

🔰 Introduction

  • Biodiversity we see today is the result of 2.5 to 3.5 billion years of evolution.

  • With the arrival of humans 👨‍👩‍👧‍👦, biodiversity started declining rapidly due to overuse of species.

  • India 🇮🇳 → 66 National Parks, 368 Sanctuaries, 14 Biosphere Reserves 🌿

🌿 Biodiversity

  • Bio + Diversity = Biodiversity

  • Bio = Life, Diversity = Variety

  • Refers to the number & variety of organisms in a given area.

  • High in tropical regions 🌴, decreases towards polar regions ❄️.

📊 Levels of Biodiversity

  1. Genetic Biodiversity 🧬 → Variations in genes of a species.

  2. Species Biodiversity 🐒🐦🐟 → Variety of species in an area; hotspots show high diversity.

  3. Ecosystem Biodiversity 🌍 → Diversity of ecosystems, habitats, processes & distribution.

💰 Economic Importance of Biodiversity

  • Source of food 🍚, medicines 💊, cosmetics 💄, timber 🌳, fish 🐟

  • Basis of many resource disputes ⚖️

  • Provides agriculture crops, livestock, forest resources, pharma products

🌎 Ecological Importance of Biodiversity

  • Maintains energy flow & nutrient cycle 🔄

  • Controls climate & gases 🌫️

  • Greater diversity = more survival chances & stability

🔬 Scientific Importance

  • Helps us study origin & evolution of life

  • Understands role of species in ecosystem

🛡️ Conservation Measures (Convention on Biodiversity)

  • Protect endangered species 🦏

  • Proper planning & management

  • Conserve varieties of crops, fodder plants, timber, livestock

  • Protect wildlife habitats 🏞️

  • Ensure safe growth areas for species

  • Regulate trade of plants & wildlife 🌍

🚫 Measures to Stop Biodiversity Decline

  • Afforestation 🌲

  • Control pollution & pesticides ☢️

  • Protect wildlife habitats

  • Ban trade of endangered species 🚫

  • Save species from extinction

⚠️ Causes of Biodiversity Destruction

  • Habitat change 🏗️

  • Population growth 👥

  • Alien species 🌱

  • Pollution 🏭

  • Overexploitation 🌲

  • Hunting 🎯

  • Natural disasters 🌊🌋

🐾 Species

  • Group of organisms with similar characteristics.

  • Estimated 20 lakh – 100 million species exist, but only ~1 crore identified.

  • 99% extinct species once lived on Earth.

🌍 Great Diversity Centers

  • 12 countries with highest species richness 🌱

  • Mexico, Colombia, Ecuador, Peru, Brazil, Congo, Madagascar, China, India, Malaysia, Indonesia, Australia

🌐 IUCN (International Union for Conservation of Nature)

  • Established: 5 October 1948 (France)

  • Earlier name: International Union for Protection of Nature

  • Publishes Red List 📕 of endangered species

🏷️ IUCN Classification

  1. Endangered Species 🦏 → At high risk of extinction

  2. Vulnerable Species 🐅 → May soon become endangered if not protected

  3. Rare Species 🦜 → Very small population, found in limited regions

🇮🇳 Measures by Government of India

  • Wildlife Protection Act, 1972

  • Establishment of National Parks & Sanctuaries 🦌

  • Creation of Biosphere Reserves 🌿 for natural protection

🔥 Hotspots of Biodiversity

  • Areas with very high species richness

🌍 Ecological Hotspots by Continent

  • South & Central America: Central Highlands, Andes, Atlantic Forest (Brazil)

  • Africa: Eastern Madagascar, Tanzania Arc Mountains, Upper Guinea Forest

  • Asia: Western Ghats, Eastern Himalayas (India), Sri Lanka, Indonesia, Malaysia, Philippines

  • Australia: Queensland, Melanesia (New Caledonia)


Class 11 Geography Chapter 15 – Life on Earth Notes in English | CBSE Exam Ready

 

🌍 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

  1. Terrestrial Ecosystem 🌳

  2. 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:

    1. Marine Ecosystem: Ocean 🌊, Estuaries 🌅, Coral Reefs 🐠

    2. 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:

    1. Primary Consumers: Eat plants 🌿 → Grasshopper, Sheep 🐑, Goat 🐐, Rabbit 🐇

    2. Secondary Consumers: Eat primary consumers 🥩 → Wolf 🐺, Fox 🦊, Snake 🐍, Bird 🐦

    3. 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:

  1. Energy Flow ⚡

  2. Food Chain & Food Web 🍽️

  3. 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

  1. Grazing Food Chain 🌿

    • Begins from plants (producers) → herbivores → carnivores (tertiary consumers).

    • Energy lost at each level via respiration, excretion, decomposition.

  2. 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

  1. Gaseous Cycle 🌫️: Source is atmosphere & oceans

  2. 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

  1. Population Growth 👥 → Pressure on natural resources

  2. Destruction of Forests 🌳 → Deforestation, floods, droughts

  3. Technological Progress 🏭 → Pollution & industrial waste

  4. 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 🌡️


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