Chapter 15: Our Environment Notes

The ecosystem is derived from the Greek word ‘Oikos’ which means home and ‘systema’ means system i.e a limited space in which living beings interact or collaborate with each other and environmental factors like water, temperature, humidity, etc., and dependencies on these factors to survive. An ecosystem can be of various types depending on its size. For example

  • It can be small which is called a micro-ecosystem eg. Pond.
  • It can be of medium size ecosystem eg. A forest.
  • It can be of large size known as biome eg. A tropical rainforest.

Components of the Ecosystem

The ecosystem is made of 2 factors i.e., biotic and abiotic components. Biotic components are the factors that are living factors that affect the ecosystem. Abiotic factors are those factors that are nonliving and affect the environment and ecosystem. Both components maintain an equilibrium in the ecosystem.


Abiotic Components

It consists of non-living or physical components like water, light, temperature, humidity, soil, nutrients, etc. which affect living beings in terms of growth, development, maintenance, and reproduction. These are also known as ecological factors. These factors affect the life of species in all forms of environmental conditions such as in water or on land. Abiotic components change from one ecosystem to another. There are three types of abiotic components:

Edaphic Factors

Edaphic means floor or ground surface. This factor basically includes soil and substratum. The texture of the soil, its nutrient composition, and its density tell about the type of species or trees that will grow there.

Topographic Factors

This includes surface exposure altitude, slope, etc. Human activities lead to modification in these components. They have an impact on various biotic and abiotic factors. Such as farming, mining, and forest cutting.

Climate Factors

These factors are based on the atmosphere and include light, temperature, humidity, and wind. The speed of the wind and its direction influence the humidity of an area. Similarly, the temperature of the lives of many species for eg. Some species require a particular temperature to survive.

Effects of Abiotic Factors on Organism

An organism has many ways in which it responds to abiotic factors.

  • Decomposers: Many organisms can regulate their body temperature along with the environment but some organisms lack this ability so they have varying body conditions as per the new environment. Such organisms are called conformers.
  • Regulators: These are those organisms that maintain their body conditions irrespective of the environment. For eg., Humans maintain their body temperature at 37°C in both summer and winter.
  • Migrate: There are many organisms that can not able to maintain their body conditions according to their respective environment. Such organisms in order to survive migrate to a region that suits their body conditions. For eg., the Siberian crane migrates to India when the conditions are not supportive of its survival.
  • Diapause: It is a natural eruption in the development of some animals by the decrease of metabolic activity. Mostly found in insects, mites, a few crabs, and snails.
  • Suspend: When the condition is not according to the organisms instead of migrating they enter a stage of suspension where their growth and development are suspended for a particular period of time. For eg., Bears went into hibernation in winter.

Biotic Components 

Biotic means are related to living. It contains all living components such as fungi, bacteria, animals, plants, etc. As they use energy for their survival so on the basis of energy requirements they are divided into three parts:


Producers basically include trees that fulfill the requirements of other organisms for food and oxygen. Through photosynthesis, they gain the energy required by them under the presence of chlorophyll and sunlight.


It includes carnivores, herbivores and omnivores. Carnivores depend on flesh for their food requirements.  Herbivores eat plants and get energy from them.  Omnivores eat both plants and flesh. Consumers help in maintaining the balance in the ecosystem by following the food chain.


These are also called saprophytes. These are the organisms that feed on dead and decay and convert them into organic compounds. They are important for the nutrient content in the soil. With more will be nutrients more species and trees can able to grow.

FAQs on Ecosystem and its Components

Q1: What is an Ecosystem?


Ecosyem is the area where both the biotic and abiotic components interact to live.

Q2: What are the Components of an Ecosystem?


Ecosystem have 2 components on the basis of they are living or non-living. These components are:

  1. Biotic Components: All living organism in the ecosystem eg. bacteria, plant, animals etc.
  2. Abiotic Components: All abiotic factors which include soil, temperature, ph etc.

Q3: What are the different types of an ecosystem?


Ecosystem are divided into 2 different ecosystem:

  1. Teerestial Ecosystem
  2. Aquatic Ecosystem

On the basis of ecosystem is made with aid or without aid:

  1. Natural Ecosystem
  2. Artificial Ecosystem

Q4: What are the functions of an ecosystem?


The main function of an ecosystem are:

  1. Productivity
  2. Nutrient cycling
  3. Decomposition
  4. Water dynamics

What is Food Chain?

The food chain is the straight chain of organisms that starts with the producer and then the energy is transferred from the producer to the carnivores and ends with the decomposer in the food web. The food chain explains the feeding relationship of organisms.

Those who produce their own food by changing the organic energy into chemical energy are known as autotrophs and in the process known as photosynthesis that organisms have chlorophyll for making food. Thus, they are called Producers or Autotrophs. Some organisms which are dependent on the producers as a source of food are termed, consumers. Consumers are also known as herbivores. Those who feed on the producers are known as primary consumers and place on the second trophic level and they occupy the second trophic level. Those who feed on primary consumers are known as small carnivores or secondary consumers and secondary consumers occupy the third trophic level. Large carnivores which feed on secondary consumers or small carnivores are known as tertiary consumers and they form the fourth trophic level.

The food chain has four main components those are:
  1. Sun: Plants use solar energy for the process of photosynthesis. 
  2. Producer: These are the organisms that produce food themselves through the process of photosynthesis. Producers are also known as Autotrophs. Solar energy is converted into chemical energy which transfers from one trophic level to the other as a source of energy. Producer Example-Algae, green plants, cyanobacteria, etc.
  3. Consumer: These are the organisms that consume the food produced by the producers, also known as heterotrophs. Heterotrophs are those organisms that cannot make their own food and depends on other for food. The consumer can be herbivores, i.e., that organism that feeds upon green plants, or carnivores i.e., organisms that feed upon another organism. Consumers are the largest part of any food chain. 
  4. Decomposers: Organisms that break down complex organic substances into simple inorganic substances, which then go into the soil and they are an important part of maintaining the nutrients cycle in the environment.

The food we consume acts as fuel to our body and it provides energy and helps in maintaining homeostasis. Due to the interactions among the components of the environment energy flows from one component of the system to another component. Autotrophs absorb energy from sun rays and convert it into chemical energy. It is this energy that supports all the activities. The energy pass in a unidirectional upward movement from producer to decomposer. When one form of energy is converted into another form of energy, some amount of energy or a huge amount of energy is lost to the environment and can’t be used again.

Another aspect of the food chain is that some chemicals enter our body through the food chain and start accumulating in the body this is known as Biomagnification. Humans use various chemicals and pesticides to protect crops from pests and other diseases. These chemicals reach soil or water bodies when they are washed off. On the one side, from the soil, these are absorbed by the plants along with water & minerals. On the other side, the water bodies, are taken up or consumed by aquatic plants & animals. In this way, chemicals enter the food chains. These chemicals are not degradable. So they go on accumulating at each trophic level. It’s human beings who occupy the topmost level of the food chain. It can also be defined as a  process in which the maximum concentration of chemicals gets accumulated in the body of organisms occupying the topmost trophic level. This is the reason wheat, rice, fruits, vegetables, and meat contains varying amount of chemicals.

Food Chain

Key Points

  • When sunlight falls on the leaves of green plants they capture 1% of the energy of sunlight and convert it into food energy.
  • When green plants are consumed by herbivores or primary consumers, a certain amount of energy is lost to the environment in the form of heat. The remaining energy would be used up by the herbivores for other activities like digestion, growth, and reproduction.
  • Around 10% of the food eaten is turned into its own body and would be made available for secondary consumers.
  • The food chain is generally up to 4-5trophic levels. A great amount of energy is lost at each trophic level as heat loss thus, very little energy remains for the consumers of the next trophic level. Consumers or organisms at third and fourth trophic levels receive less energy than the organisms at first and second trophic levels.
  • On a normal basis, we see the food web very commonly instead of the food chain.

Law of Leinweber

This is also known as the 10% rule.

  • This law states that the energy passed from one trophic level to the next level will only the 10% of the previous tropic level.
  • The flow of energy is unidirectional and always in the upward direction.
  • There is a max. loss of energy as heat loss so for the next level they have less amount of energy to transfer.
Energy Pyramid

Types of Food Chain

Food chains are of two types on the basis of the beginning of the food chain. Detritus and Grazing Food chain.

Grazing Food Chain

The food chain in which the producers are autotrophs i.e, they make their own food by photosynthesis. Autotrophs are later on consumed by herbivores. Herbivores by the carnivores. The energy is passed on with each tropical level. Primary energy is taken from the sun.

Sun-> Autotrophs-> Herbivores-> Small Carnivores-> Large Carnivores-> Top Predator

Detritus Food Chain

Detritus Food Chain

This food chain starts with dead organic material. The Detritus food chain starts with the different organisms i.e, bacteria, algaefungi, etc, which decompose the organic material like the detritus of plants, and decomposing animals. The decomposer gains energy from decomposition, the decomposer is later on eaten by the small carnivores and the energy is restored.

  • Primary consumers of the detritus food chain are decomposers
  • The Detritus food chain helps in regulating nutrient cycling.
  • They have larger energy transfers in terrestrial habitats.

Food Web

The length and complexity of the food chain differ greatly. In our environment, one organism can be eaten by two or more kinds of organisms which are then eaten by others. So instead of a straight-line food chain, this relationship can be shown as a series of branching lines, this graphical representation is known as the Food Web. The Food web also can be defined as an interconnection of food chains.

Food Web

The energy captured by producers or autotrophs is passed on to the secondary consumers, then to tertiary consumers, and so on. So the flow of energy is said to be unidirectional and it doesn’t revert back. As we already discussed, some amount of energy is lost from each trophic level in the form of heat loss to maintain their temperature. so for the next transfer, the energy is less and energy goes on decreasing. Thus, the top trophic level receives less energy than the previous ones.

FAQs on Food Chain

Question 1: What are the first organisms in a food chain?


The food chain starts with the producer. On the basis of producer, the food chain is classified into two types: Detritus and Grazing food chain.

Question 2: What is a Food chain? 


A food chain is a series of organisms which are dependent on the next as a source of food.These organisms take part at various biotic levels and form food chains.

Question 3: Define trophic level.


 A trophic level is formed by each step or level of the food chain.

Question 4: What are food web?


In our environment one organism can be eaten by two or more kind of organisms which are then eaten by others.So instead of a straight line food chain, this relationship can be shown as a series of branching lines,this graphical representation is known as Food web.

Question 5: What is the difference between a food chain and a food web?


The food chain is the linear line that represents the feeding relationship of the organisms. Whereas in the food web multiple food chains are interconnected and show how different plants and animals are connected. 

Question 6: Which organisms occupy the first trophic level and why?


The producers or autotrophs occupy the first trophic level. Because they produce food by themselves by the process of photosynthesis and autotrophs or producers fix up the solar energy and they are the one who make it available for consumers of the next trophic levels.

What is an Ozone Layer?

The ozone layer is found in the upper locales of the stratosphere where it protects the earth from the unsafe bright rays of the sun. These radiations can cause skin malignant growth in people. The ozone layer absorbs mostly 95-99% of rays emitted by the sun, if the rays are not absorbed it directly affect the living organisms present on the earth like- skin cancer in humans, and it also weakens the immune system.

Scientists found a hole having an area of approximately 23.2 million square kilometers present in the ozone layer over Antarctica on 13 October 2022. The primary reason for ozone depletion is Carbon tetrachloride, methylbromide, chlorofluorocarbons, and hydrofluorocarbons.

What is Ozone Layer Depletion?

The process in which the ozone layer starts depleting is because of some chemical substances release by industries or some human activities. This process is known as Ozone layer Depletion.

Ozone layer depletion is the diminishing of the ozone layer present in the earth’s upper atmosphere. This happens because chlorine and bromine particles in the climate interact with ozone and they affect the ozone atoms. One chlorine can break 100,000 particles of ozone.

While ozone depletion happens generally in the stratosphere, the consumption is particularly set apart over the Antarctic area. This added to the making of a wide area of the thin ozone layer, well known as the ozone opening. Industries release some harmful chemical substances which release chlorine and bromine which on exposure with the Uv rays start depleting the ozone layer. The harmful substance that causes ozone layer depletion is known as Ozone Depleting Substances (ODS)

Chlorine ozone-depleting substances include- Chlorofluorocarbon, hydrofluorocarbons, methyl chloroform, and carbon tetrachloride. While bromine ozone-depleting substances include methyl bromide, halons, and hydrofluorocarbons. Chlorofluorocarbon is the main factor present in the large amount that causes ozone layer depletion. 

Ozone Layer Depletion

In response to these concerns, the international community has taken action through the Montreal Protocol to reduce the production and consumption of ozone-depleting substances, resulting in a slow recovery of the ozone layer. In this article, we will discuss the causes, effects, and solutions to ozone layer depletion, and how it affects our planet’s health and well-being.

Causes of Ozone Layer Depletion 

Ozone layer depletion is a prime concern and ozone layer depletion is caused by multiple factors. The different factors that cause ozone layer depletion are listed below:


The primary factor of ozone depletion and ozone opening is chlorofluorocarbons also known as CFCs, particularly produced by halocarbon refrigerants, solvents, aerosols, sprays, AC, and froth-blowing specialists. CFCs released by them travel to the atmosphere, and their UV rays break the CFC molecule and Chlorine is released. Chlorine reacts with the ozone layer molecule and starts reacting with them.

Nitrogenous Compounds

Different nitrogen compounds like NO2, NO, and N2O also cause ozone layer depletion.

Unregulated Rocket Launches

Rocket launches are also the major cause of ozone layer depletion. Research shows that this is the major factor that causes ozone layer depletion more than chlorofluorocarbon.

Natural Causes

Due to sun spots or stratospheric wind also cause ozone layer depletion. But natural causes are not the prime cause of ozone depletion.

Ozone Depleting Substances

Ozone-depleting substances are chemicals that affect or cause ozone layer depletion. For example-Halons, Chlorofluorocarbons, hydrofluorocarbons, etc. 

Following are the Ozone depleting substances which cause ozone layer depletion.

Ozone Depleting substanceSource of ODS
HydrofluorocarbonAC, Solvents, Fire-extinguishers.
Carbon tetrachlorideFire extinguishers, and Solvents
ChlorofluorocarbonsRefrigerators, AC, Solvents, etc.
Methyl ChloroformAerosols, and Adhesives

Effects of Ozone Layer Depletion

Ozone layer depletion directly affect all living organisms. Due to ozone layer depletion, the UV rays direct come to the earth’s surface and do harmful effects on mankind and the environment.

Effect on Humans

Due to ozone depletion UV rays do not absorb and they came directly to the earth’s surface. Humans directly came in contact with UV rays which cause skin cancer, Skin disease, UV rays affect eye cataracts, and mutation in the genome.

Effects on Animals

If animals come in direct contact with UV rays that leads to skin cancer ad eye cancer.

Effect on Environment

When plants came in direct contact with UV rays it affects the photosynthesis rate, growth, and flowering of a plant. The whole first also effect if it gets direct exposure to UV rays.

Effect on Marine Ecosystem

Planktons are the most abundant food present in the aquatic ecosystem food chain. UV rays directly affect the plankton which affects the aquatic food chain directly.

Prevention for Ozone Layer Depletion

Ozone depletion affects living organisms in a harmful way. There are some preventive measures to control ozone layer depletion. Such methods are:

Minimize the use of vehicles

Vehicles cause air pollution: release greenhouse gases which are a major factor in global warming and also lead to ozone depletion. Minimizing the use of Vehicles helps to control ozone depletion.

Also read: Greenhouse Effect

Stop using ODS

Avoiding using appliances that release ozone-depleting substances such as AC, refrigerators, etc. Replacing the fire extinguishers with halons-free extinguishers.

Prohibition of Nitrous Oxide

 Nitrous Oxide causes ozone depletion. Avoiding Nitrous oxide reaction help to prevent Ozone layer depletion.

Use Eco-friendly Cleaning Products

Most cleaning products contain chemicals that released chlorine and bromine. They find their way into the atmosphere and cause ozone layer depletion.

FAQs on Ozone Layer Depletion 

Q1: What is Ozone layer depletion?


THe thinning of the ozone layer because of the harmful chemical process is known as Ozone Layer depletion.

Q2: What is the main cause of Ozone Layer Depletion?


The main cause of Ozone Layer Depletion is halons and chlorofluorocarbons. They react with the ozone molecular and break the molecules which lead to ozone layer depletion.

Q3: Why is the ozone layer important?


The ozone layer is important because it absorbs and reflects most of the harmful rays that come from the sun. If it is not present it leads to various skin disorders and cancers in humans and animals. 

Q4: When did ozone depletion start?


The early 1980s are the time when scientists observe the thinking of the ozone layer above the south pole.


Garbage is defined as items or materials that should be discarded because they no longer serve any purpose for us or are of no use to us. We consistently generate massive amounts of garbage. Garbage is frequently associated with a strong odor, and a large amount of garbage may emit harmful fumes. As a result, we place such items in dustbins to be transported to distant locations in order to ensure that our environmental factors are perfect and sound. Garbage waste includes vegetable and fruit strips, extra prepared food items, waste paper, and plastic materials, and a variety of other waste items.

Classification of Garbages

Biodegradable wastes

Biodegradable wastes are any organic matter that can be decomposed into a simpler substance with the help of microbes. They are environmentally friendly and include all organic wastes derived from plants, agricultural wastes, and so on.

Non Biodegradable wastes

Non-biodegradable wastes are wastes that cannot be decomposed and cause pollution in our environment. These wastes, which include plastics, paints, metals, and glasses, can be recycled.

Sources of Garbage 

  • Industrial wastes include those generated by power plants, compound plants, concrete production lines, food preparation businesses, and textile industries, with each delivering waste specific to the industry of which it is a part.
  • Domestic wastes include food remains, leafy foods skins, apparel items, used plastic items, and so on, and are generated by family units, offices, and schools, among other places.
  • Commercial: This specifies the type of waste generated by commercial activities such as disposable plastic cutlery, food items, food bundles, textiles, and so on.
  • Agricultural waste includes waste generated by attempted agricultural activities, such as husks, expired medications, compost and pesticide containers, and so on.

Managing the Garbage we Produce 

Waste management entails the safe and efficient disposal of waste as well as the transformation of waste into new products. As a result, waste management is the responsibility of both the government and the citizens. And when either of the two parties fails to do their part, the waste management system collapses. This will eventually result in a full-fledged garbage crisis. As a result, we will look at the waste management strategies that can be used.


  • Recycling is the process of treating and converting waste into new products that can be used as raw materials or for product packaging by manufacturers. Plastics, glass, and paper are some examples of recyclable waste. As a result, recycling lowers the cost and energy required to produce new products. It also reduces the amount of waste disposed of in landfills.
  • Along with dumping and segregating waste, we must go a step further in reducing the amount of garbage we produce by applying the 3R’s principle – reduce, reuse, and recycle.
  • Reducing, reusing, and recycling. We can save energy, trees, and other natural resources and protect the environment by following
    • Reduce: Consumption should be cut back. A product should only be used when it is absolutely necessary.
    • Reuse: Instead of throwing away items like old newspapers and envelopes, consider reusing them.
    • Recycle: Glass, paper, aluminum, and plastic can all be recycled and reused.


Composting is the decomposition of organic waste into manure. Food and plant wastes are among the wastes that can be decomposed. As a result, they are appropriate for organic farming. Composting is the long-term accumulation of organic materials so that microbes can begin breaking them down. This is one of the safest waste management methods, but it is a little slow.


  • ‘Incineration’ means ‘to reduce to ashes.’ Incineration is the process of burning a substance at a high temperature (greater than 1000°C) to produce ash.
  • Incineration takes place in an incinerator. The Municipality of a City disposes of waste on a large scale by using incinerators.
  • In the incinerator, solid waste is burned at high temperatures. All organic matter in waste is extracted as carbon dioxide and water vapor.
  • Household waste, chemical waste, and biological waste are all destroyed through incineration. Incineration significantly reduces waste volume. This is due to the fact that when a large amount of waste material is burned, only a small amount of ash is left behind, which can be disposed of in a landfill.


  • The most common waste disposal strategy today is to dump waste in landfills. This strategy entails collecting biodegradable waste and compacting it before burying it beneath the ground.
  • Landfills, on the other hand, will be located in a confined area far from civilization. Furthermore, they are only appropriate for lands with deep groundwater levels. As a result, finding suitable landfill sites is becoming increasingly difficult.
  • This strategy is based on the idea that bio-degradable materials will decompose naturally. Furthermore, the gas emitted by landfills can be used as fuel.


  • Bioremediation is a biotechnological process that reduces or eliminates contamination. It is a waste management technique that employs organisms to remove or utilize pollutants from polluted areas.
  • When it comes to executing the Bioremediation process, microorganisms such as Bacteria and Fungi play a key role. Bacteria are the most important microbes in this process because they convert waste into nutrients and organic matter.
  • Even though this is an efficient waste management process, bioremediation cannot eliminate all contaminants. Bacteria can easily digest contaminants such as chlorinated pesticides and clean up oil spills, but microorganisms are incapable of destroying heavy metals such as lead and cadmium.

Plasma Gasification 

Plasma gasification is the process of converting waste to synthetic gas by subjecting it to high temperatures. An electrically powered plasma torch is used to vaporize organic matter into synthetic gases for this purpose (carbon monoxide and hydrogen). Slag is produced as a byproduct of this process.

Sewage treatment 

  • Sewage is the dirty drain water containing urine and feces that is carried from our homes by underground pipes (called sewers).
  • Sewage treatment generates clean water, which is discharged into the river. The organic matter in sewage is ‘digested’ in sewage treatment plant digesters to produce sewage gas’ (a type of biogas) and ‘manure.’
  • Untreated sewage that is dumped into a river can pollute the water. Sewage is thus disposed of by treating it at a sewage treatment plant (or sewage works).

Frequently Asked Questions 

Question 1: Explain garbage disposal. 


Garbage is typically deposited in roadside bins or given to garbage collectors. Municipal workers collect garbage from dumping sites and transport it to landfill sites away from residential areas. The garbage is separated, and recyclable items are sent to be recycled. The remainder of the items is left on the landfill site, which has been covered with soil.

Question 2: Mention the sources of garbage created. 


  • Sewerage and kitchen waste are examples of household waste.
  • Coal, paper, and ash are examples of industrial waste.
  • Agricultural waste, including the husk, fibers, and straw.
  • Community waste, such as that generated by shops, offices, and hospitals.
  • Wires, broken computers, and batteries are examples of electronic waste.

Question 3: What are the biogas generation measures to manage the garbage? 


Biodegradable waste, such as food, animal waste, or natural industrial waste from various food packaging industries, is sent to bio-degradation plants. They are converted to biogas in bio-degradation plants through degradation with the assistance of bacteria, fungi, or other microbes. The natural issue serves as food for the small-scale animals in this case. Debasement can occur either vigorously (with oxygen) or anaerobically (without oxygen). This procedure produces biogas, which is used as fuel, and the buildup is used as manure.

Question 4: Explain the vermicomposting method of waste disposal  


Vermicomposting is the process of converting organic matter into nutrient-rich manure by using worms. Worms eat and digest organic matter. The by-products of digestion excreted by the worms enrich the soil with nutrients, promoting the growth of bacteria and fungi. It’s also a lot more efficient than traditional composting.

Question 5: Explain the waste compaction method of garbage disposal. 


Waste materials like cans and plastic bottles are compacted into blocks and recycled. This process prevents metal oxidation and reduces the need for airspace, making transportation and positioning easier.

Question 6: Explain the disposal of solid waste. 


Solid waste is typically disposed of through incineration, a process in which waste materials are heated to extremely high temperatures and reduced to ash, flue gas, and heat.

Question 7: What exactly is waste disposal?


Waste disposal is the process of destroying or recycling unused, old, or unwanted household, agricultural, medical, or industrial waste.

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