Our Environment

Eco-System – What are its Components?

We often hear about the “environment” on TV, in newspapers, and from people around us. Our elders say it has changed over time. Global meetings are held to discuss environmental issues. This chapter explores how different components of the environment interact and how we impact them.

What is an Ecosystem?

• Ecosystem: All living organisms (plants, animals, microorganisms, humans) and their physical surroundings interacting together.
• Components:
  • Biotic: Living organisms.
  • Abiotic: Non-living factors like temperature, rainfall, wind, soil, and minerals.

Examples of Ecosystems

• Garden: Different plants, animals, and their interactions.
• Natural Ecosystems: Forests, ponds, lakes.
• Human-made Ecosystems: Gardens, crop fields, aquariums.

Organisms in an Ecosystem

• Producers:
  • Make their food from sunlight (photosynthesis).
  • Examples: Green plants, some bacteria.
• Consumers:
  • Depend on producers or other consumers for food.
  • Types:
    • Herbivores: Eat plants.
    • Carnivores: Eat other animals.
    • Omnivores: Eat both plants and animals.
    • Parasites: Live off other organisms.
• Decomposers:
  • Break down dead organisms and waste.
  • Examples: Bacteria, fungi.
  • They recycle nutrients back into the soil.

Food Chains and Webs

What is a Food Chain?

• A food chain shows a series of organisms feeding on each other.
• Each level in a food chain is called a trophic level.
• The first level: Autotrophs (Producers) like green plants.
• The second level: Herbivores (Primary Consumers) like deer.
• The third level: Small Carnivores (Secondary Consumers) like frogs.
• The fourth level: Larger Carnivores (Tertiary Consumers) like lions.

How Energy Flows in a Food Chain

• Food provides energy to do work.
• Energy flows from the sun to plants, then to animals, and finally to decomposers.
• Green plants capture about 1% of sunlight and turn it into food energy.
• Only about 10% of energy is passed on to the next level because energy is lost as heat, used for digestion, and for doing work.

Important Points about Energy Flow

• Energy flow is one-way; it doesn’t go back to the previous level.
• Only a small amount of energy reaches the next level.
• Most food chains have only 3 or 4 levels due to energy loss.
• There are more producers than consumers.

Food Webs

• Food chains are not always straight lines. They can branch out.
• An organism can be eaten by multiple organisms and can eat several organisms.
• This creates a complex network called a food web.

Unidirectional Energy Flow

• Energy captured by plants doesn’t return to the sun.
• Energy passed to herbivores doesn’t go back to plants.
• Energy diminishes at each trophic level.

Biological Magnification

• Harmful chemicals like pesticides enter the food chain from polluted water or soil.
• These chemicals accumulate in plants and animals.
• They are not degradable and build up in higher levels of the food chain.
• Humans, being at the top, get the highest concentration of these chemicals.
• This is called biological magnification.

How Do Our Activities Affect the Environment?

We are part of the environment, and our actions change it. Two major problems are the depletion of the ozone layer and waste disposal.

Ozone Layer and Its Depletion

• What is Ozone?
  • Ozone (O3) is made of three oxygen atoms.
  • It is a poison at ground level but essential in the upper atmosphere.
  • It protects Earth from harmful ultraviolet (UV) radiation from the Sun.
• How is Ozone Formed?
  • UV light splits oxygen (O2) into single oxygen atoms (O).
  • These atoms combine with O2 to form ozone (O3).
• Ozone Depletion
  • Ozone levels began to drop in the 1980s.
  • Depletion is linked to chemicals like chlorofluorocarbons (CFCs) used in refrigerators and fire extinguishers.
  • In 1987, a global agreement was made to reduce CFC production.

Managing the Garbage We Produce

• Types of Waste
  • Daily waste includes kitchen waste, paper, medicine bottles, old clothes, and broken footwear.

Biodegradable vs. Non-biodegradable

• Biodegradable: Broken down by biological processes (e.g., vegetable peels).
• Non-biodegradable: Not broken down by natural processes (e.g., plastics).
• Non-biodegradable waste can harm the environment and persist for a long time.

Key Takeaways

• Ozone protects us from UV radiation but is depleted by CFCs.
• Waste management is crucial, with biodegradable waste breaking down naturally and non-biodegradable waste persisting and potentially causing harm.

Understanding Biodegradable and Non-biodegradable Waste

Garbage in Our Surroundings

• Common sights in towns and cities include heaps of garbage.
• Tourist spots often littered with empty food wrappers.
• Previous classes discussed dealing with garbage; now we explore it more deeply.

Impact of Lifestyle Changes on Waste Generation

• Improved lifestyles lead to more waste.
• Increased use of disposable items.
• Modern packaging often non-biodegradable.
• Consider the environmental impact of these changes.

Disposable Cups in Trains: A Case Study

• Historical Context:
  • Tea was once served in reusable plastic glasses.
  • Disposable cups were introduced for hygiene reasons.
• Alternatives and Their Impacts:
  • Clay cups (kulhads) could deplete fertile top-soil.
  • Disposable paper cups are now used.
  • Compare advantages of paper cups over plastic cups.

Key Takeaways

• Understanding the difference between biodegradable and non-biodegradable waste is crucial.
• Proper waste management practices at home and in communities are essential.
• Lifestyle changes significantly impact waste generation and environmental health.
• Continuous exploration and adaptation of waste management strategies can help mitigate environmental damage.

Chapter Summary:

• The various components of an ecosystem are interdependent.
• Producers make energy from sunlight available to the rest of the ecosystem.
• There is a loss of energy as we go from one trophic level to the next, which limits the number of trophic levels in a food chain.
• Human activities impact the environment.
• The use of chemicals like CFCs has endangered the ozone layer.
• The ozone layer protects against ultraviolet radiation from the Sun, and its damage could harm the environment.
• The waste we generate may be biodegradable or non-biodegradable.
• The disposal of the waste we generate is causing serious environmental problems.