Our Environment-Notes

An ecosystem consists of two main components: biotic and abiotic. The biotic components include all living organisms such as plants, animals, microorganisms, and humans that interact with each other. The abiotic component consist of non-living physical factors such as temperature, rainfall, wind, soil, and minerals that form the environment around the living organisms. These components work together, interacting and maintaining a balance in nature, forming a functional unit called an ecosystem.

The biotic components are further classified into producers (plants that prepare their own food through photosynthesis), consumers (animals that feed on plants or other animals), and decomposers (microorganisms that break down dead organic matter). The abiotic components provide the necessary physical conditions for the survival and growth of the living organisms within the ecosystem.

Ecosystems can be natural, such as forests, ponds, and lakes, or artificial, such as gardens, crop fields, and aquariums. In any ecosystem, both components are interdependent, with energy flowing from producers to consumers and decomposers maintaining the nutrient cycle. This harmonious interaction sustains the ecosystem's balance and health.

Biotic components of an ecosystem are all the living organisms that interact with each other and their environment. These include plants, animals, fungi, microorganisms like bacteria, and even the waste products or remains of these organisms. Biotic components are essential for the functioning of the ecosystem as they perform different roles that maintain ecological balance.

Biotic components are classified into three main groups:

• Producers (autotrophs):
  These are mainly green plants and some bacteria that make their own food through photosynthesis, using sunlight to convert carbon dioxide and water into energy-rich nutrients.
• Consumers (heterotrophs):
  These organisms cannot produce their own food and depend on other organisms for nourishment. They include herbivores (plant-eaters), carnivores (meat-eaters), omnivores (eat both plants and animals), and parasites.
• Decomposers (saprophytes):
  These are mainly fungi and bacteria that break down dead plants and animals, recycling nutrients back into the soil, which supports producers and sustains the ecosystem.

Together, these biotic components form a complex web of interactions where energy flows from producers to various consumers and nutrients are recycled by decomposers, ensuring the continuity and balance of life in the ecosystem. Their interdependence makes the ecosystem stable and functional.

Abiotic components are the non-living physical and chemical factors in an ecosystem that influence the survival, growth, and distribution of living organisms. These include elements like sunlight, temperature, water, air, soil, minerals, pH levels, and wind, which provide the essential conditions for life to thrive. Without these factors, biotic components cannot function effectively, as they regulate processes like photosynthesis, respiration, and nutrient availability.​

Abiotic components interact closely with biotic ones; for instance, sunlight drives plant growth, while soil supplies minerals to roots and water supports metabolic activities. Variations in these factors, such as extreme temperatures or low rainfall, can limit species diversity and population sizes in an ecosystem. They act as limiting factors that determine the boundaries and productivity of different ecosystems, from deserts to forests.​

In a balanced ecosystem, abiotic components cycle through energy flows and nutrient exchanges, sustaining the overall harmony. For example, rainfall replenishes water bodies, enabling aquatic life, while atmospheric gases like oxygen and carbon dioxide facilitate breathing and photosynthesis. This interdependence ensures the ecosystem remains stable and self-sustaining.

Producers are living organisms in an ecosystem that can make their own food using sunlight, water, and carbon dioxide through a process called photosynthesis. They are also known as autotrophs because they produce organic food from inorganic substances. Green plants are the most common producers on land, while in aquatic ecosystems, producers include algae and phytoplankton. Producers form the base or first trophic level of any food chain and provide energy not only for themselves but also for all other organisms in the ecosystem.

Consumers, also known as heterotrophs, are organisms in an ecosystem that cannot produce their own food and must obtain energy by feeding on producers or other consumers. They occupy higher trophic levels after producers and are essential for transferring energy through the food chain. Examples include herbivores like deer and rabbits that eat plants, carnivores like lions and eagles that prey on other animals, and omnivores like humans and bears that consume both plants and animals.

Consumers are classified based on their feeding habits

• Primary consumers (herbivores):
  They directly feed on producers, converting plant material into energy for the next levels.
• Secondary consumers (carnivores or omnivores) :
  They eat primary consumers, controlling their populations.
• Tertiary consumers (top carnivores):
  They prey on secondary consumers and act as apex predators, maintaining ecosystem balance.

Heterotrophs play a vital role in energy flow, with only about 10% of energy passing to the next trophic level due to losses as heat. Their interactions prevent overpopulation of any single species and support biodiversity. Without consumers, ecosystems would lack regulation and nutrient distribution.

Decomposers, also called saprophytes, are organisms that break down dead and decaying organic matter into simpler substances. These include fungi, bacteria, and certain insects, which play a vital role in recycling nutrients back into the soil and environment. By decomposing dead plants, animals, and waste, decomposers convert complex organic compounds into simpler inorganic molecules like carbon dioxide, water, nitrogen, and phosphorus that plants can absorb and use for growth.

Decomposers act as natural recyclers in an ecosystem by cleaning up dead material and preventing the accumulation of waste. They release enzymes to digest the dead matter externally and absorb the nutrients, which sustains the nutrient cycle and supports the food web. Without decomposers, essential nutrients would remain locked in dead organisms, disrupting ecosystem balance and growth of producers.

Thus, decomposers maintain the health and stability of ecosystems by ensuring continuous nutrient availability and enabling energy flow through the food chain. They complete the cycle of matter, making life sustainable for all organisms in the environment.

Biological magnification is the gradual increase in the concentration of non‑biodegradable, toxic substances at each higher trophic level of a food chain. Substances such as certain pesticides (for example DDT), industrial chemicals and heavy metals do not get broken down easily, so they remain in the bodies of organisms and are passed on when one organism is eaten by another.​

At the producer level, each plant may absorb only a very small amount of the toxin from soil or water, so the concentration in its body is low. However, a herbivore eats many such contaminated plants, so the total quantity of toxin in its body becomes higher; a carnivore that eats several herbivores accumulates an even greater amount. Thus, organisms at the top of the food chain, including humans, receive the maximum concentration of these harmful chemicals, which can damage their nervous system, reproductive capacity and overall health.​

This phenomenon is particularly dangerous because it cannot be easily reversed once persistent pollutants enter an ecosystem. To reduce biological magnification, the use of long‑lasting pesticides and industrial chemicals must be strictly controlled, and safer, biodegradable alternatives and biological methods of pest control should be encouraged.

Human activities affect the environment by disturbing its natural balance through pollution, excessive resource use, and careless waste generation. These actions change the quality of air, water, and soil, harm living organisms, and even influence global climate patterns.

Pollution and resource overuse

• Burning fossil fuels in vehicles, power plants, and industries releases harmful gases like carbon dioxide, sulphur dioxide, and nitrogen oxides, causing air pollution, respiratory diseases, and global warming.
• Discharge of untreated sewage, industrial effluents, and chemical fertilizers into rivers and lakes leads to water pollution, killing aquatic life and making water unsafe for human use.
• Overuse of natural resources such as forests, minerals, and fossil fuels leads to deforestation, habitat loss, and depletion of non-renewable resources, reducing biodiversity and disturbing ecosystems.

Ozone depletion and climate change

• Certain man-made chemicals, especially chlorofluorocarbons (CFCs) once used in refrigerators, air-conditioners, and aerosol sprays, rise up and damage the ozone layer, which protects us from harmful ultraviolet (UV) radiation. Thinning of the ozone layer increases the risk of skin cancer, eye problems, and harm to crops and marine life
• Excessive emission of greenhouse gases from burning coal, oil, and natural gas traps more heat in the atmosphere, leading to global warming and climate change. This causes melting of glaciers, rising sea levels, and more frequent extreme weather events like floods, droughts, and heatwaves.

Waste generation and non-biodegradable materials

• Our lifestyle produces large amounts of solid waste such as plastics, metals, glass, and electronic waste; much of it is non-biodegradable and remains in the environment for a very long time. Open dumping and burning of garbage pollute land, air, and water, and can spread diseases.
• Plastic bags and packaging choke drains, harm animals that accidentally eat them, and break into microplastics that contaminate soil and water bodies. Improper disposal of chemical and biomedical waste can poison ecosystems and enter food chains.

Impact on ecosystems and biodiversity

• Deforestation for agriculture, cities, and industries destroys natural habitats, leading to the disappearance of many plant and animal species and reducing biodiversity. Loss of biodiversity weakens ecosystem stability and makes it harder for nature to recover from disturbances.
• Overfishing, hunting, and introduction of invasive species by humans disturb food chains and food webs, sometimes causing the collapse of local ecosystems. When one species is removed or drastically reduced, many others depending on it are also affected.

Need for eco-friendly practices

• To reduce our negative impact, it is important to adopt eco-friendly habits such as using public transport, saving electricity and water, avoiding single-use plastics, and practising the 3Rs – reduce, reuse, and recycle.
• Planting trees, protecting forests and wildlife, treating sewage and industrial waste, and encouraging the use of cleaner energy sources like solar and wind can help restore environmental balance and ensure a healthier future.

Managing the garbage we produce means dealing with our daily waste so that it harms the environment as little as possible and keeps us healthy. Instead of just throwing everything in one bin, we handle it step by step in a smart and scientific manner.

What does “managing garbage” mean?

• It is the planned handling of waste from homes, schools, markets and industries so that land, air and water do not get polluted.
• Good management reduces bad smell, spread of flies and diseases, and the pressure on landfills and dumping grounds.

Reduce – create less waste

• Prefer items with minimum packaging, carry your own water bottle and lunch box instead of buying disposables.
• Say “no” to single‑use plastics like straws, thin carry bags and plastic cutlery; this directly cuts down the quantity of garbage.

Reuse – use things again

• Use cloth bags instead of new plastic bags each time; reuse glass jars and boxes for storage at home.
• Repair and reuse notebooks, toys or electronic gadgets whenever possible instead of throwing them away quickly.

Recycle – give materials a new life

• Separate paper, cardboard, metals, glass and some plastics and send them to recycling centres or kabadiwalas.
• Recycling saves raw materials, energy and space in landfills because the same material is converted into new products.

Segregate biodegradable and non‑biodegradable waste

• Keep a green bin for biodegradable waste (vegetable peels, leftover food, garden leaves, paper) and a blue bin for non‑biodegradable waste (plastics, metals, glass).
• When waste is mixed, it is dirty and difficult to treat; when it is separated, each type can be handled properly.

Compost and biogas from biodegradable waste

• Kitchen and garden waste can be collected in a pit or compost bin and allowed to rot with the help of microbes to form nutrient‑rich compost for plants.
• In some places, biodegradable waste is fed into biogas plants to produce a clean fuel for cooking and lighting along with manure as a by‑product.

Safe handling of non‑biodegradable and hazardous waste

• Non‑biodegradable waste that cannot be recycled, like certain plastics, should be sent to engineered landfills or special treatment facilities instead of open dumping.
• Hazardous waste such as old batteries, medicines, paints and e‑waste must be collected separately and processed in specialised plants so that poisonous chemicals do not leak into soil and water.

Our role as responsible citizens

• Follow the 3Rs (Reduce - Reuse - Recycle) in daily life, participate in cleanliness drives, and support door‑to‑door segregated waste collection in the neighbourhood.
• When each family manages its own garbage carefully, the total load on the city decreases and the environment remains cleaner, greener and safer for everyone.

• The various components of an ecosystem are interdependent.
• The producers make the 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, this limits the number of trophic levels in a food-chain.
• Human activities have an impact on the environment.
• The use of chemicals like CFCs has endangered the ozone layer. Since the ozone layer protects against the ultraviolet radiation from the Sun, this could damage the environment.
• The waste we generate may be biodegradable or non-biodegradable.
• The disposal of the waste we generate is causing serious environmental problems.