Class 10 Ch 13 Our Environment

• All the interacting organisms in an area together with the non-living constituents form an Eco-system.
• किसी क्षेत्र के सभी जीव तथा वातावरण के अजैव कारक संयुक्त रूप से पारितंत्र बनाते हैं।
• Types: Natural (Forests, Lakes) & Artificial (Gardens, Crop-fields).

• Abiotic (अजैव): Physical factors like temperature, rainfall, wind, soil.
• Biotic (जैव): Living organisms, classified as:
  – Producers: Green plants & blue-green algae (make food from inorganic substances).
  – Consumers: Depend on producers (Herbivores, Carnivores, Omnivores, Parasites).
  – Decomposers: Microorganisms (Bacteria/Fungi) that break down dead remains.
• Role of Decomposers: They replenish the soil with nutrients by breaking down complex organic substances into simple inorganic ones. Without them, the earth would be covered in garbage! 🦠

• A series of organisms feeding on one another.
• जीवों की वह श्रृंखला जिसमें एक जीव दूसरे जीव को आहार के रूप में खाता है।
• Example (Forest): Grass $\to$ Deer $\to$ Tiger.
• Example (Pond): Phytoplankton $\to$ Insects $\to$ Fish $\to$ Crane.

• In nature, organisms are eaten by many other organisms.
• Instead of a straight line, the relationship is a branching line called a Food Web.

• Each step or level of the food chain is a Trophic Level.
• Level 1: Producers (Autotrophs).
• Level 2: Primary Consumers (Herbivores).
• Level 3: Secondary Consumers (Small Carnivores).
• Level 4: Tertiary Consumers (Large Carnivores).

• 1% Rule: Green plants capture only about 1% of sun’s energy.
• 10% Law: Only 10% of the energy is transferred to the next trophic level. Most is lost as heat/metabolic processes.
• Unidirectional Flow: Energy captured by autotrophs does not go back to the sun! Energy flow is one-way.

• Pesticides/chemicals enter the food chain through soil/water.
• Since they are non-biodegradable, they accumulate progressively at each trophic level.
• Because Humans occupy the top level, the maximum concentration of these chemicals is found in our bodies! ⚠️

• Ozone ($O_3$): Found at higher levels of atmosphere. Shield against harmful UV rays.
• Formation: $O_2 \xrightarrow{UV} O + O$; then $O + O_2 \to O_3$.
• Depletion: Caused by CFCs (Chlorofluorocarbons) used in refrigerators & fire extinguishers.
• UNEP (1987): Agreement to freeze CFC production.

जीवनशैली में परिवर्तन के कारण कचरे की मात्रा बढ़ गई है।

• Biodegradable: Substances broken down by biological processes (Fruit peels, Paper, Cotton).
• Non-biodegradable: Not broken down (Plastics, DDT, Glass). They persist and harm the environment.

• Increased use of disposables (like plastic cups in trains).
• Switch to Kulhads was tried but lead to loss of topsoil.
• Now paper cups are preferred as they are biodegradable.