our environment class 10 assignment

NCERT Solutions for Class 10 Science Chapter 15 Our Environment

Chapter 15 Our Environment Class 10 NCERT Solutions

Ncert solutions for class 10 science chapters:, what is acid rain, what is trophic level, what percentage of solar energy is trapped and utilized by plants, how ozone layer is advantage for us, what limits the number of trophic levels in a food chain, contact form.

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NCERT Solutions for Class 10 Science Chapter 15 - Our Environment

• NCERT Solutions

NCERT Solutions for Chapter 15 Science Class 10 - Free PDF

Class 10 Science Ch 15 Solutions for Our Environment will help students understand all the basic to complex concepts of environmental Science. With the help of Our Environment Class 10 PDF, you get answers to all the present questions at the back of your textbook. By the end of 2030, it is estimated that the world will be needing twice as many resources that we are using now and that our planet won't be able to provide us. Thus, learning about the environment becomes more critical in this century than it was ever before. Our environment chapter's PDF is created by a unique team of teachers with experience in environmental studies for a long time.

You will get the answers to your questions from experts, and each solution is precise and to the point. You can also download this PDF in your local storage, so you don't need to worry about internet connectivity to access the files and the answers.

You can also download NCERT Solutions for Class 10 Maths to help you to revise complete syllabus and score more marks in your examinations.

Access NCERT Solutions for Class 10 Biology Chapter 15- Our Environment

1. Why are some substances biodegradable and some non-biodegradable?

Ans: Substances that might be rotten and diminished to easier substances by microorganisms functioning on are known as biodegradable and people substances that can not be acted upon by microorganisms and aren't diminished into easier substances are units known as non-biodegradable substances. Examples of biodegradables - vegetable wastes, paper, cotton etc. On the opposite hand, materials that can not be rotten by the action of microorganisms/decomposers are non-biodegradable. For example- plastic, glass, polyethene etc.

2. Give any two ways in which biodegradable substances would affect the environment.

  Ans: Two ways within which perishable substances would have an effect on the atmosphere area unit -

Biodegradable waste is a substance that can be broken down easily and naturally by natural sources like water, oxygen, sun radiation, or microorganisms. 

Biodegradable waste produces a foul smell and that’s why they result in pollution.

3. Give any two ways in which non-biodegradable substances would affect the environment.

Ans: Non-biodegradable substances affect the environment in the following ways:

They contaminate soil and water resources as they can't be rotten by microorganisms.

These substances, if accidentally eaten by stray animals, will damage them and might even cause their death.

4. What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

Ans: A trophic level is the steps in a food chain.

Consider the following scenario:

For example:

Grass - Trophic level I

Grasshopper - Trophic level II

Frog - Trophic level III

5. What is the role of decomposers in the ecosystem?

Ans: Decomposers eat decomposing and dead materials. They contribute to the clean-up of the environment.

6. What is ozone and how does it affect any ecosystem?

Ans:  Oxygen in the form of ozone is a type of oxygen. Ozone's molecular formula is 03. In the atmosphere, it can be found in higher concentrations. It blocks the sun's damaging ultraviolet radiation from reaching the earth. UV rays have been linked to skin cancer, cataracts, and the extinction of plant and animal life.

7. How can you help in reducing the problems of waste disposal? Give any two methods.

Ans: The following methods can be taken to alleviate the trash disposal issue:

a. Reduce, reuse, and recycle as much as possible.

b. Use smart waste disposal techniques such as separate trash cans for different types of waste.

8. Which of the following groups contain only biodegradable items?

(a) Grass, flowers and leather

(b) Grass, wood and plastic

(c) Fruit-peels, cake and lime-juice

(d) Cake, wood and grass

 Ans: (c) and (d)

9. Which of the following constitute a food chain?

(a) Grass, wheat and mango

(b) Grass, goat and human

(c) Goat, cow and elephant

(d) Grass, fish and goat

10. Which of the following are environmental-friendly practices?

(a) Carrying cloth-bags to put purchases in while shopping

(b) Switching off unnecessary lights and fans

(c) Walking to school instead of getting your mother to drop you on her scooter

(d) All of the above

11. What will happen if we kill all the organisms in one trophic level?

Ans: If we kill all the organisms in one trophic level, the transfer of energy to the next level will stop.

It'll lead to overpopulation at one level. This would disturb the food chain and cause the collapse of the ecosystem.

12. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?

Ans: Yes, the impact of removing all the organisms at a trophic level will be different for different trophic levels. For example, on removing producers; herbivores would not be able to survive or they would migrate and the ecosystem would collapse. If herbivores are removed, producers would grow unchecked and carnivores would not get food. If carnivores are removed, herbivores would increase to unsustainable levels and could destroy the producers. If decomposers are removed, the dead animals would pile up due to which the environment would become polluted. In addition to this, if dead animals will not decompose, the recycling of nutrients in the soil will be stopped and its fertility will be reduced. As a result, the green cover of the earth will be lost. Thus to maintain the balance of the ecosystem the presence of organisms is necessary at each trophic level.

13. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?

Ans: Biological magnification is that the increase in the concentration of harmful chemical substances like pesticides within the body of living organisms at every biological process level of an organic phenomenon is named biological magnification. Yes, levels of biomagnification would increase because the biological process level would increase and would be the very best for the uppermost biological process level. it might have an effect on their organic process like growth, replica, etc.

14. What are the problems caused by the non-biodegradable wastes that we generate?

Ans: Following are the problems caused by the non-biodegradable wastes that we generate: 

They do not disintegrate and get accumulated within the setting.

Harmful non-biodegradable chemicals enter the organic phenomenon and cause biological magnification.

They cause air, land, water and soil pollution.

If not treated, the native population of animals, birds, plants and humans is severely suffering from intense non-biodegradable wastes there in space.

15. If all the waste we generate is biodegradable, will this have no impact on the environment? 

Ans: If the quantity of perishable waste will increase, then this excess perishable waste will certainly have an impression on the surroundings. The surplus perishable waste is rotten by the action of decomposers then it releases harmful greenhouse gases. These gases can accumulate within the atmosphere, inflicting warming. Perishable waste is recycled simply by the decomposers like bacteria and fungi. It'll have solely this dangerous impact on our surroundings that several Of the gases discharged throughout the decomposition method might end in global warming.

16. Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?

Ans: The ozone layer is the protective layer of the earth from harmful rays. It plays a significant role in protecting all living and nonliving organisms. If a layer is broken no organism will survive. Following measures, the steps being taken to limit this harm. 

We must always minimize the employment of vehicles.

We must always not encourage the burning of fossil fuels.

It's currently necessary for all the producing firms to form CFC- free refrigerators throughout the globe.

Students who are looking for NCERT Solutions for Class 10 Science Chapter 15 - Our Environment PDF can opt for Upcoming Exams and also You can Find the Solutions of All the Science Chapters below.

Related Study Materials for CBSE Term II Class 10 Science Chapter 15 Our Environment 

CBSE Class 10 Science Revision Notes Chapter 15 - Our Environment

Important Questions for CBSE Class 10 Science Chapter 15 - Our Environment

NCERT Exemplar for Class 10 Science Chapter 15 - Our Environment (Book Solutions)

CBSE Sample Paper for Class 10 Science

CBSE Class 10 Science: Previous Year Question Paper and Solutions Free Download (2007-2020)

NCERT Science Solutions Class 10 - Chapter wise PDF Download

Chapter 1 - Chemical Reactions and Equations

Chapter 2 - Acids, Bases and Salts

Chapter 3 - Metals and Non-metals

Chapter 4 - Carbon and Its Compounds

Chapter 5 - Periodic Classification of Elements

Chapter 6 - Life Processes

Chapter 7 - Control and Coordination

Chapter 8 - How do Organisms Reproduce?

Chapter 9 - Heredity and Evolution

Chapter 10 - Light Reflection and Refraction

Chapter 11 - Human Eye and Colourful World

Chapter 12 - Electricity

Chapter 13 - Magnetic Effects of Electric Current

Chapter 14 - Sources of Energy

Chapter 15 - Our Environment

Chapter 16 - Management of Natural Resources

NCERT Solutions For Class 10 Science Chapter 15

Topics Covered in This Chapter:

Food chains and webs

Managing the garbage that we produce

Points Covered in This Chapter

An ecosystem's numerous components are interrelated.

The sun's energy is made available to the rest of the environment by the producers.

As we progress from one trophic level to the next, we lose energy, which restricts the number of trophic levels in a food chain.

The environment is impacted by human activity.

The usage of chemicals like CFCs has put the ozone layer in jeopardy. Because the ozone layer protects the environment from the sun's UV rays, this might be harmful to the ecosystem.

We may create biodegradable or non-biodegradable garbage.

The way we dispose of the rubbish we create is doing havoc on the ecosystem.

Types of Questions: NCERT Class 10 Science Chapter 15 

The types of questions that students may expect from the Chapter 15 Our Environment in the CBSE Class 10 Science Term II exam are listed below.

Very short answer type questions

Multiple-choice questions

Short-answer type questions

Long-answer type questions

Class 10 Science Chapter 15 NCERT Solution is one of the chapters which students love as it is one the easiest chapters that you will be reading in your Class 10th Science textbook. When you have chemical formulas from Chemistry, theorems from physics, and difficult names from biology, this chapter gives your mind to take a foot off from the pedals of hard work. Most of the things that you get to learn from this chapter are already known to you in one way or the other. As a result, the student receives good marks in their exams whenever a question comes from this chapter, which is most of the time. 

Class 10 Science Chapter-wise Marks Weightage in CBSE Term I and Term II 2021-22

It is advisable for students to go through all the chapters covered in the syllabus for Class 10 Science Term I and Term II for exam preparation. Also, knowing the weightage of marks for each chapter will help them get an upper hand to chalk out their study plan and utilise their time efficiently while they revise the chapters. Hence, the chapter-wise marks weightage for Class 10 Science CBSE Term I and Term II is given in the below table for the reference of students.

Benefits of Learning About Our Environment in Class 10th

From small animals and insects to giant animals and even glaciers benefit from human's learning in the field of environmental education. Environmental Science helps students in the 10th standard achieve good marks as it has engaging lessons that are easy to understand. You don't need to keep many things in mind as you are learning about the various natural world working criteria.

With Environmental Science, teachers and parents try to aware kids about the importance of nature. A study suggests children who play outside are more physically active, have better nutrition value in their bodies, and are more creative. 

This is the only subject which helps promote student's health while at the same time teaching them how to keep the environment and its surroundings healthy. With the Environmental Science outdoor activities, students become more active, which reduces the common health issues that the modern-day child is suffering from. Some of these are obesity, blood sugar, kidney failure, etc. 

In addition to this, when you are studying Environmental Science, you get to know things you need to succeed in the future. You get to investigate and define the problems that are around you and find ways to solve them through the subject only. 

With Environmental Science, students can find how to create a better world with a greener environment safe for plants, animals and even humans. 

Key Features of NCERT Solutions for Class 10 Science Ch-15 Our Environment

Prepared by highly experienced teachers.

Precise answers that provide a comprehensive understanding of the chapter.

In accordance with the revised syllabus for the Class 10 Science CBSE Term II exam.

Available as a free downloadable PDF.

Accessible on the Vedantu mobile app as well as on its official website.

Easy to understand answers supported by an explanation.

Prepared as per the latest CBSE guidelines.

FAQs on NCERT Solutions for Class 10 Science Chapter 15 - Our Environment

1. What types of questions are there in the NCERT Solutions for Class 10 Science Chapter 15 Our Environment?

Ans: The types of questions that you will come across in the NCERT Solutions for Class 10 Science Chapter 15 are as follows.

Short answer type questions

Long answer type questions

There are 3 multiple-choice questions and 1 very short answer type of question in the NCERT Solutions Class 10 Science Chapter 15. You can answer the very short answer type of questions in one sentence. There are about 7 short answer type of questions and 5 long answer type of questions in the NCERT Solutions for Class 10 Science Chapter 15 Our Environment. All the questions given in the exercise of the chapter are solved as per the CBSE Class 10 guidelines are solved in these NCERT Solutions.

2. Where can I get the best NCERT Solutions for Class 10 Science Chapter 15 Our Environment online?

Ans: You can get the best NCERT Solutions for Class 10 Science Chapter 15 Our Environment on Vedantu. It is a leading ed-tech and students from all across the country vouch for the readability and reliability of NCERT Solutions provided by Vedantu. The NCERT Solutions for Class 10 Science Chapter 15 Our Environment are in alignment with the latest CBSE Class 10 syllabus and answer format. So, you can download and refer to these NCERT Solutions for your exam preparation. These NCERT Solutions will guide you to write precise answers for all types of questions commonly asked in the examination.

3. Can I download the NCERT Solutions for Class 10 Science Chapter 15 Our Environment for free?

Ans: Yes, you can download the NCERT Solutions for Class 10 Science Chapter 15 Our Environment for absolutely free of cost. These NCERT Solutions are available in PDF format on Vedantu. You can download this PDF and refer to these solutions even when you are not connected to the internet.

4. What is meant by biological magnification? Give an example.

Ans: The gradual accumulation of toxic chemical compounds in the body of living organisms at various trophic levels of the food chain, is called biological magnification. As we go up a food chain, the concentration of these toxic substances will go on increasing, and the maximum concentration of these toxic substances can be observed at the highest trophic level. 

A very common example of biological magnification is the accumulation of insecticides or chemical fertilizers in organisms at various levels of food chains.

5. What is the environment according to the Class 10 Syllabus?

Ans: The environment is something that consists of various biotic and abiotic components, such as plants, animals, human beings, and other physical non-living components that coexist in an area together and interact with each other in order to maintain the balance of nature. The environment can also be defined in simpler terms as the immediate surrounding in which one lives. You will come across this topic in the NCERT Solutions for Class 10 Science Chapter 15 given on Vedantu.

6. What is Our Environment?

Ans: Our Environment is Chapter 15 of the Class 10 Science NCERT textbook. This chapter deals with our ecosystem, ecology and the various aspects related to our surroundings and its betterment. It is crucial to understand that the unnecessary use of natural resources will lead to severe problems in the future when our planet fails to provide us with any more resources. Vedantu’s NCERT Solutions for Class 10 Science Chapter 15 Our Environment PDF is created by a team of experts.

7. How can we protect our environment according to Class 10?

Ans: The environment is something that needs to be protected not just for nature’s benefit but for our own benefit as well. Exploiting the natural resources and the environment as a whole will cost future generations to come. So, everyone must try to save the environment by altering their transport choices, or reducing the number of chemicals and usage of effluents, planting more trees, making wise energy choices and not depleting the natural resources. 

8. Why are plastics and other man-made substances not broken down by the action of bacteria or other Saprophytes? How are these substances broken down?

Ans: Plastics and other man-made substances are non-biodegradable in nature and hence, they are not decomposed by microorganisms or decomposers like bacteria or other saprophytes present in the environment. These non-biodegradable wastes then accumulate in the environment, pollute land and water and result in a global problem. These plastics and man-made substances ultimately settle at the bottom of the oceans and are usually broken down over a long period of time by the action of sunlight, marine animals, and oxidation.

9. How is it advantageous to use Vedantu for Our Environment Chapter 15 Class 10 Science?

Ans: The Vedantu NCERT Solutions for Our Environment Chapter 15 Class 10 Science are beneficial for the students of Class 10, who are willing to gain knowledge as well as score good marks in their examination. These solutions are prepared by a group of experts who have worked hard in putting up a simpler version of the story, summarised it and also given the solutions to each question in a very precise manner. The PDF can be downloaded free of cost from the Vedantu website (vedantu.com) and the app.

NCERT Solutions for Class 10 Science

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Our Environment CBSE Class 10 Science Revision Notes Chapter 15

Things around us is known as Environment . It consists of living component also known as biotic component and non-living component also known as Abiotic Component.

The interaction between abiotic and biotic components is defined as ecosystem.  It is a self sustaining and functional unit of biosphere. The term ecosystem was coined by Sir Arthur Tansley (OLYMPIAD)

Types of Ecosystem

There are two types of ecosystem- natural ecosystem and artificial ecosystem. The ecosystem present naturally is known as Natural Ecosystem. Example of Natural Ecosystem are forests, grasslands, deserts, ponds, lakes, rivers, estuaries, sea. The ecosystem which is man-made is known as Artificial Ecosystem . For Example Gardens, Aquariums and Agro ecosystem which is the largest manmade ecosystem.

Fig.1. Components of ecosystem

Abiotic Factors Include  - Climatic factors such as rain, temperature, wind etc. Another abiotic factor is edaphic factors such as soil, pH, minerals etc.

Biotic Factors Include -

Producers which can make their own food, such as plants, blue green algae etc.

Consumers feed on producers. Such as herbivores. In consumers there are- primary consumers, secondary consumers, tertiary consumers etc.

Carnivores are flesh eating animals.

Omnivores consume both plants and animals.

Parasites live inside and depend upon living host.

Saprophytes feed on dead remains of plants and animals.

Food Chain is defined as series of organisms in order in which organisms feeds on another organism. There are various steps in food chain in which energy is transferred, each level is known as trophic level. Energy is always transferred unidirectionally.

Characteristics of food chain

There is a unidirectional flow of energy from producers to consumers.

There are generally 3 to 4 trophic levels.

It is always straight

Organism can occupy different trophic levels in different food chain.

A 10 percent law is followed in energy transfer which was given by Raymond Lindeman. This law states that “only 10 percent of energy is transferred from one trophic level to another trophic level”. The remaining 90 percent will be used by the present trophic level in different processes. Therefore there are usually 3-4 trophic levels in a food chain.

Fig.2. Energy transfer in trophic level

Interconnection of food chain is known as Food Web . It shows how food chain are interdependent.

Characteristic of Food Web

Food webs are never straight as they are formed by interlinking of food chains.

Food web provides alternative pathways of food availability. If a particular species is destroyed, the predator can feed on an alternative species.

Food webs increase ecosystem stability.

Fig.3. Food web

Ecological Pyramids

Ecological Pyramid is a graphical representation to show biomass or bioproductivity. There are different ecological pyramids such as pyramid of biomass, pyramid of number and pyramid of energy. Pyramid of number indicates number of individuals at different trophic levels. Pyramid of biomass indicates biomass of the members of the food chain present at different trophic levels. Pyramid of energy indicates energy at different trophic levels.

Fig.4. Upright Pyramids

Pyramid of number and pyramid of biomass can be inverted also . In aquatic ecosystem pyramid of biomass is inverted.

Fig.5. Inverted pyramid

Impact of Human Activities

Biological magnification.

The concentration of harmful substances increases with every trophic level. This is known as Biomagnification . Addition of pesticides in one trophic level increases the concentration of pesticides in other trophic level.

Fig.6. Biomagnification

Ozone Layer

High UV radiation break down oxygen into oxygen atoms. These oxygen atoms when combine with oxygen, they form ozone.

Depletion of Ozone Layer

The thickness of the ozone layer over Antarctica was found to be decreased in the year 1985. This is defined as ozone depletion. This is due to excessive use of chlorofluorocarbons in refrigerators, ACs, aerosols, etc. Thinning of ozone would allow penetration of Ultraviolet rays into earth’s atmosphere causing blindness, skin cancers and mutations.

In 1987 United Nations Environment Programme (UNEP) signed an agreement to limit the usage of CFCS. This is known as Montreal Protocol .

Fig.7. Reaction of CFC with ozone

Consequences of Ozone Depletion

Exposure of UV rays causes skin cancer. UV-rays damage the eyes also. It affects humans, plants as well as animals.

Garbage Disposal

Waste materials are known as garbage. There are two types garbage - Biodegradable Garbage and Non-biodegradable Garbage.

Garbage that can be completely decomposed by the microorganism are called Biodegradable Garbage ., such as fruit and vegetable peel, sewage.

Substances which cannot be decomposed through microorganisms are known as Non-biodegradable Garbage , For Example, Plastic, Glass, Pesticide, Metals, Radioactive Elements etc.

Methods of Waste Management

Waste disposal is a very important part of day to day life. There are different methods of waste disposal management- sewage treatment plant, biogas plant, land fillings, recycling, incineration, composting and reuse.

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Our Environment Notes And Questions | Chapter 15 Class 10

Our environment notes and questions.

Below are some of the very important NCERT Class 10 Science chapter 15 our environment notes and questions. These Class 10 our environment notes and questions have been prepared by expert teachers and subject experts based on the latest syllabus and pattern of term 2. Questions with Answers to help students understand the concept.

These Questions for Class 10 Science our environment notes and questions are very important for the latest CBSE term 2 pattern. These class 10 notes and Q and A are very important for students who want to score high in CBSE Board.

We have put together these NCERT  Questions of Class 10 Science chapter 15 our environment notes and questions for practice on a regular basis to score high in exams. Refer to these Questions with Answers here along with a detailed explanation.

All those things and set of conditions that influence the life of an organism like their growth, survival, development and reproduction, constitute the environment.

It is composed of physical surroundings (e.g. air, water), living beings (e.g. plants, animals) and climatic conditions (e.g. rainfall, temperature) of the region.

It is the structural and functional unit of the biosphere. It is a stable ecological unit where regular input of energy and circulation of matter takes place. The term ecosystem was coined by AG Tansley (in 1935).

All the interacting or living organisms (biotic components) in an area together with the non-living constituents (abiotic components) of the environment form an ecosystem, e.g. a lake, a field or a forest.  

Types of Ecosystem

There are two types of ecosystem, i.e. natural and artificial ecosystem,

1. Natural Ecosystem

The naturally existing ecosystem without any human support is called a natural ecosystem. Depending upon the habitats, natural ecosystems may be terrestrial (desert, grassland and forest) and aquatic (ponds, lakes, estuaries and marine).

2. Artificial Ecosystem

An ecosystem which is created and maintained by humans is called an artificial or man-made ecosystem. It relies on human efforts to sustain. It does not possess a self-regulating mechanism.

e.g. Aquariums, botanical gardens, field crops, etc. Agro-ecosystem is the largest man-made ecosystem.

Components of Ecosystem  

The ecosystem encompasses both living (biotic) and non-living (abiotic) components of the earth.

1.Biotic Components

These include all the living organisms present in the ecosystem, i.e. plants, animals and microorganisms.

On the basis of food, the different living organisms can be categorized into three groups. These are as follows

(i) Producers . All green plants and certain blue-green algae which can produce food by the process of photosynthesis are producers. These are also called autotrophs. These are the source of nutrition for the rest Of ecosystem.

(ii) Consumers . These are dependent on producers for their nutritional requirement and consume food prepared by producers. These are also called heterotrophs.

Consumers can be further divided into the following three categories:

Herbivores . These are primary consumers which feed directly on the producers, i.e. plants. e.g. Grazing animals.

Carnivores . The carnivores which feed on herbivores are called secondary consumers.

Some are predators which attack and kill their prey and feed on their bodies. Some are scavengers that feed on dead animals that they find. These are called tertiary consumers.

Omnivores . These are animals that feed on both plants and animals, e.g. humans and bears.

(iii) Decomposers . These are microorganisms which feed on decaying and dead organic matter. They break down the remains of dead animals and plants, to release simpler inorganic materials, making nutrients available to producers. 

e.g. Bacteria and fungi.

2. Abiotic Components 

The abiotic components of an ecosystem are the non-living components on which living organisms depends. These components are light, temperature, water, atmospheric gases, wind, etc. 

It is a linear network of living organisms in a community through which energy is transferred in the form of food.

It describes the relationship between organisms about ‘who eats whom’.

On the basis of choice of habitat, food    chains are of two  

(i) Terrestrial food chain. It is the (bod chain present ou land,

e.g. Grass — Insects — Snake — Hawk.

(ii) Aquatic food chain. It is the chain present in different water bodies.

e.g. Phytoplankton — Zooplankton — Fish — Shark

Trophic Levels

The transfer of food or energy takes place through various steps or levels in the food chain known as trophic levels. 

The producers (autotrophs) are present at the first trophic level. They fix solar energy, making it available for consumers (heterotrophs). The herbivores or 9the primary consumers are found at the second trophic level.

Small carnivores or secondary consumers are present at the third trophic level. The large or the tertiary consumers form the fourth trophic level.

Energy Flow

• The green plants in a terrestrial ecosystem capture about 1% of the energy of sunlight (light energy). They convert  it into food (chemical energy).
• When green plants are eaten by primary consumers, a great deal of energy is lost as heat and an average of 10%  of the energy of food eaten by an organism is turned back into its own body and made available for the next level of consumers. This is known as the 10% law (Lindemann in 1942).

Therefore, 10% can be taken as the average value for the  amount of organic matter that is present at each step and reaches to the next trophic level.

• The loss of energy at each step is very large. Only a little energy is available for the next level of consumers, food chains generally consist of three or four steps.

• The flow of energy is unidirectional, i.e. the energy which passes to the next trophic level, does not come back to the lower trophic level.

Click Below To Learn Term 2 Syllabus All Chapters

• Chapter 4: Carbon And Its Compounds Notes / Questions 
• Chapter 5 : Periodic Classification of Elements Notes / Questions
• Chapter 8 : How Do Organism Reproduce  Notes / Questions
• Chapter 9 : Heredity And Evolution Notes / Questions
• Chapter 12 : Electricity Notes / Questions
• Chapter13 : Magnetic Effects of Electric Current Notes / Questions
• Chapter15 : Our Environment Notes / Questions 

It is the interconnection of different food chains, which correlate at various trophic levels operating in an ecosystem, Each organism is generally eaten by two or more other kinds of organisms. They in turn are eaten by several other organisms.

Environmental Problems

Human are an integral part of the environment. Various human activities pollute the environment in various ways. Serious environmental problems such as biomagnification, ozone layer depletion, waste accumulation are as follows:

Biological Magnification or Biomagnification

It is the phenomenon of progressive increase in the concentration of non-biodegradable toxicants in organisms at each successive trophic level. It is also called bioconcentration. These toxic chemicals enter the food chain through pesticides like DDT.

The maximum concentration of these chemicals gets accumulated in humans as they occupy the topmost place in any food chain.

Depletion of Ozone Layer

Ozone (O3 ) is a molecule formed by three atoms of oxygen. It is found in the stratosphere. It shields the surface of the Earth fli)m harmful ultraviolet (UV) radiations of the Sun.

Formation of Ozone Layer

Ozone is a product of UV radiations acting on oxygen (0 2 ) molecules. The high energy UV radiations split apart some tuoleeulav oxygen (0 2) into free oxygen (O) atoms. These are very reactive and combine with the molecular oxygen to form ozone.

Ozone Depleting Substance

The increasing use of synthetic chemicals like Chlorofluorocarbons (CFCs) which are used in refrigerants as coolant and in fire extinguishers are responsible for ozone layer depletion.

In the atmosphere UV radiation break down CFCs molecules and release chlorine atom these atoms on reacting with Ozone, disassociate Ozone molecule into oxygen. 

Thus, it leads to depletion of Ozone layer

Managing the garbage we produce

The household waste is called garbage.  Every household produces a lot of garbage on a daily basis. Improvement in our Lifestyle have resulted in Greater amount of waste material generation. 

These way substances can be divided into two main groups:

(i) Biodegradable substances . The substances which can be disposed off naturally by the action of

micro organizations1 like bacteria, fungi, etc., arc called biodegradable substances.

e.g. Tea leaves, waste paper, left over food, etc.

(ii) Non-Biodegradable substances . The substances that cannot be converted into harmless simpler forms by the action of Microorganisms are called non-biodegradable substances. These are toxic, harmful, may be inert and accumulate in the environment or food chain.

e.g. Plastics, insecticides, heavy metals, etc.

Methods of Waste Disposal

Various methods of waste disposal are as given below

(i) Recycling. It is the processing of waste materials to form new products.

(ii) Composting. Biodegradable domestic wastes can be buried in a pit, dug into ground and are converted into compost and used as manure.

(iii) Incineration. It is the burning of a substance at high temperature to form ash. It is commonly used to dispose hospital waste.

(iv) Landfills . Solid waste is dumped into a low lying area and covered with soil.

(v) Sewage treatment . Organic ‘material in the sewage is allowed to settle down and decompose in large tanks. The water from these tanks is cleaned and is released into water bodies.

(vi) Biogas production . In some places, sewage is decomposed anaerobically to yield biogas and manure.

Note: Disposable paper cups which are biodegradable in nature are now being used in trains instead of plastic cups and kulhads.

As the production of kulhads at a large scale resulted in the loss of top fertile layer of soil which leads to soil erosion, whereas, plastic cups are non-biodegradable in nature, therefore cause environmental problems.

Frequently Asked Questions

Short answer type questions.

1. Define an ecosystem. Draw a block diagram to show the flow of energy in an ecosystem.    (CBSE 2019)

2. (i) What do you understand about the term ecosystem?

(ii) Autotrophs are at the first level of the food chain. Give a reason.

(iii) In a food chain of frogs, grass, insects and snakes, assign trophic level to frogs. To which category of consumers do they belong to? (CBSE 2020) 

3. What is the role of decomposers in the ecosystem? (NCERT)

4. Natural water bodies are not regularly cleaned whereas an aquarium needs regular cleaning. hv? (CBSE 21)19)

5. How does studying the food chain in an area or habitat help us? Give an example of four steps of a food chain operating in a large lake.

6. Based on their feeding habits, differentiate between parasites and decomposers. 

7. What are trophic levels? Give an example of a food chain and state the different trophic levels in it, (NCERT)

8. Number of trophic levels is limited to 3-4 in a chain. Give a reason.

9. What will happen if we kill all the organisms in one trophic level?

10. State 10% law. Explain with an example how energy flows through different trophic levels.

11. Indicate the flow of energy in an ecosystem. Why is it unidirectional? (NCERT Exemplar) 

12. What do you mean by biological magnification?

13. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem? (NCERT Exemplar)

14. Write the major cause of ozone depletion. What steps should be taken to limit the damage to the ozone layer?

15. Explain how ozone being a deadly poison can still perform an essential function for our environment. (CBSE 2020)

16. Give a reason why a food chain cannot have more than four trophic levels? (CBSE 2020)

17. (i) Explain the role of UV radiation in producing ozone layer.

(ii) Mention the reaction involved.

(iii) Why is excessive use of CFCs a cause of concern?

18. How is ozone formed in the upper atmosphere? State its importance. What is responsible for its depletion? Write one harmful effect of ozone depletion. (CBSE 2019)

19. Give some Diethocls that could be applied to reduce accumulation of pesticides in our.

20. How can you help in reducing Ille prol)letn ol’ waste disposal? Give any two methods.

21. If all the waste we generate is biodegradable, will this have no impact on the environment?

22. Give any two ways ‘in which non-biodegradable substances would aflbet the environment.

23. Why should non-biodegradable wastes be discarded in two separate dustbins?

24. ‘Effective segregation of wastes at the point of generation is very important’. Justify this statement.

25. Sheenu went to a picnic where she saw a pond. Her teacher gives her an assignment to draw the pond ecosystem and show its different components. Help her to complete the assignment.

26. Name the wastes which are generated in your house daily. What measures would you take for their disposal?  (NCERT Exemplar)

27. A modern insecticide has been introduced with  certain new properties like accumulation in the bodies  of predators, broken down by soil bacteria, easily  washed into lakes and rivers and taken up by plant roots. Among all these properties, which one will help in reducing or keeping the level of environment pollution  to lowest?

28. Mona eats curd and yogurt and follows a vegetarian diet. For this food intake, what should be the trophic level occupied by her in a food chain ? 

Long Answer Type Questions

29. What are decomposers? What will be the consequence of their absence in an ecosystem?    (NCERT Exemplar)

30. (i) What are consumers? What will be the consequence of the absence of primary consumers in an ecosystem?

(ii) What will be the direction of energy transfer in each of the following cases?

• Grasshopper eaten by a frog
• Deer feeds on grass
• Deer eaten by a lion

31. (i) Will the impact of removing all the organisms in a trophic level be different for different trophic  levels ?

(ii) Can the organisms of any trophic level be removed  without causing any damage to the ecosystem? (NCERT Exemplar)

32. (i) ‘Energy flow in a food chain is unidirectional’. Justify this statement.

(ii) Explain how the pesticides enter a food chain and subsequently get into our body. (CBSE 2014)

33. (i) How do food chains get shortened? How does the shortening of food chain aflöct the biosphere?

(ii) How will you justify that vegetarian food habits give us more calories?  

34. Explain some harmful effects of agricultural pracåces on the environment. (NCERT Exemplar)

35. What is Ozone and how does it affect any ecosystem? (NCERT Exemplar) 

36. i) What is environmental pollution ?

(ii) Distinguish between biodegradable and non-biodegradable pollutants.

(iii) Choose the non-biodegradable pollutants from the list given below

Paper, DDT, Radioactive waste, Plastic, Insecticides.

37. Suggest any five activities in daily life, which are eco-friendly. (NCERT Exemplar)

38. What are the reasons for the shift from plastic to kulhads and then finally to paper cups? (CBSE 2020)

Case Based Questions

39. Read the following and answer the questions from (i) to (v) given below

Food web is the interconnection of different food chains, which correlate at various trophic levels operating in an ecosystem.

(i) How many food chains are present in the  food web?

(ii) Name the primary consumer in the given food web.

(iii) How much percentage of energy is less at each trophic level?

(iv) If all the foxes are killed due to a disease, what will be your observations about food sveb?

(v) Name the organism in which accumulation of toxic Non Biodegradable substances is the lowest.

40. Read the following and answer the questions from (i) to (v) given below

Food chains are very important for the survival of most species. When only one element is removed from the food chain it can result in extinction of a species in some cases.

The foundation of the food chain consists of primary producers. Primary producers or autotrophs can use either solar energy or chemical energy to create complex organic compounds, whereas species at higher trophic levels cannot and so must consume producers or other life that itself consumes producers.

Because the Sun’s light is necessary for photosynthesis, most life could not exist if the Sun disappeared.

Even so, it has recently been discovered that there are some forms of life, chemotrophs that appear to gain all their metabolic energy from chemosynthesis driven by hydrothermal vents, thus showing that some life may not require solar energy to thrive.

(i) If 10,000 J solar energy falls on green plants in a terrestrial ecosystem, what percentage of solar energy will be converted into food energy?

(ii) Why are decomposers not included in the food chain?

(iii) How are primary consumers different from primary carnivores?

(iv) State one reason that limits the number of trophic levels in a food chain.

(v) In the given food web, name the organism in which the highest accumulation of toxic substances is found.

41. Read the following and answer the questions from (i) to (v) given below

Each organism is generally eaten by two or more other lands of organisms. They in turn are eaten by several other organisms.

Study the figure which shows the similar relationship between various organisms of the ecosystem through a food web.

Analyze the populations and their effects on each other.

(i) How many trophic levels are there in the longest food chain?

(ii) What is the role of rabbits in the given food web?

(iii) Give the significance of the food web.

(iv) Why do all food chains start with plants?

(v) What leads an organism to increase in number? 

42. Read the following and answer the questions from (i) to (v) given below

To study the ozone layer depletion, Mrs. Sharma, a science teacher, drew the given flow chart on the blackboard. She asked students to fill the bubbles labeled as 1-5 in the flow chart.

(i) What are ozone depleting substances?

(ji) How is ozone formed?

(iii) Ravi wants to draw an ozone ‘layer in a diagram showing different layers of atmosphere, where should he label it?

(iv) What is the difference between good ozone and bad ozone?

(v) What could be the effect of ozone depletion?

1. Ecosystem is defined as the structural and functional unit of the biosphere. It is a stable ecological unit where continuous input of energy and circulation of matter occurs.

2. (i) Ecosystem is the structural and functional unit of the biosphere and is a stable ecological unit where regular input of energy  and circulation matter takes place. 

(ii) Autotrophs can make their own food in the presence of sunlight. They are the ultimate source of energy for each and every organism of a food chain. Hence, every chain always starts with producers (autotrophs) that is why they are placed at the first trophic level of the food chain. 

(iii) In given food chain, Grass — Insects — Frogs — Snakes

Frogs assign at third trophic level. They acts as secondary consumers who feeds of primary consumers (i.e. insects).

3. Organisms that feed on dead plants and animals are called decomposers, e.g. bacteria, fungi, etc. They break down the complex organic compounds present in the dead remains into simpler substances and obtain nutrition from them. These substances are released into the soil and to the atmosphere.

Thus, they play the following roles

(i) They help in recycling of materials, replenishment of the soil’s nutrients, etc.

(ii) They clean our surroundings by decomposing dead organisms and organic wastes,

4. Natural water bodies are examples of natural ecosystems. They  exist naturally without any human support, whereas an aquarium is an artificial ecosystem which is created and maintained by humans. It rely on human efforts to sustain. It does not possess a self-regulating mechanism.

5. The study of food chain in an area or habitat helps in

(i) understanding the energy transfor through organisms

(ii) understanding the ecological balance in a habitat or ecosystem.

(iii) understanding harmful human activities and disruption of ecological balance, if any.

An example of four steps of food chain operating in a large lake is as follows

Algae —Protozoa —Small fish—Big fish.

6. Parasites are organisms (animals or plants) that live in or an  other organism (host) and take benefits by deriving nutrients from it, i.e. they get food or protection from host organism, e.g. Cuscuta

On the other hands, decomposers are organisms that break down dead or decaying organisms into simple inorganic substances. e.g.  Fungi

7. The transfer of food or energy takes place through various levels in the food chain, which are known as trophic levels. e.g.

8. In a food chain, about 80-90% of the energy available at a trophic level is lost during its transfer to the next trophic level. Hence, the amount of energy available goes on decreasing at each successive trophic level.

If a plant fixes 4000 J energy, then the next three successive trophic levels will get 400 J, 40 J and 4 J, respectively (according to 10% law). If another level is added in a food chain then it will get only 0.4 J energy. Thus, usually food chains remain shorter and limited to 3-4 trophic levels only.

9. If we kill all the organisms in one trophic level, the lower trophic level will grow more in number and the higher trophic level will not survive.

Hence, flow of energy from one trophic level to another will not take place.

10. According to 10% law, only 10% of the energy entering a particular trophic level of organisms is available for transfer to the next higher trophic level.

The flow of energy through a food chain is unidirectional and it moves progressively through various trophic levels as follows

(i) Green plants capture 1% of energy of the sunlight that falls on their leaves and convert it into food energy.

(ii) When green plants are eaten by primary consumers, a great deal of energy is lost as heat to the environment. On an average only 10% of food eaten is turned into its own body and made available for the next level of consumers,

(iii) Thus, 10% can be taken as average value of the amount of organic matter present at each step and reaches the next level of consumers.

11. The flow of energy in an ecosystem occurs in the following sequence 

Sun — Producer— Herbivore—Carnivore 

                            (Primary)   (Secondary)       

The flow of energy is unidirectional because of the reasons given below

(i) Energy flows progressively from one trophic level to another and cannot revert back. Energy given out as heat is lost to the environment and does not return to be used again.

(ii) The available energy decreases at higher trophic level. Out of the total energy available at a particular trophic level, only 10% is passed on to the next trophic level, making it impossible for energy to flow in the reverse direction.

12. Biological magnification also known as biomagnification is the phenomenon of progressive increase in the concentration of non-biodegradable toxicants in organisms at each successive trophic level.

13. Biological magnification refers to the increase in the concentration of certain toxicants at each successive trophic level.

No, the levels of magnification will not be the same in all trophic levels. When the chemicals do not degrade and accumulate progressively at each trophic level, it leads to biomagnification. Biomagnification is more in organisms of higher trophic levels.

14. Depletion of ozone is mainly caused due to the excessive use of Chlorofluorocarbons (CFCs). These are synthetic chemicals which are used as refrigerants and in fire extinguishers. Steps which should be taken to limit the damage to ozone layer include

(a) Minimizing the use of aerosol spray propellants containing fluorocarbons and chlorofluorocarbons.

(b) Exercising control over large scale nuclear explosions and limited use of supersonic planes.

15. Ozone layers filter the Sun’s ultraviolet radiation (UV-B), thereby protecting the environment from its harmful effects and also play a key role in regulating temperature.

16. The energy and biomass decrease from lower to higher trophic levels, so the length of food chain is restricted and cannot have more than four trophic levels,

17. (i) UV radiation acts on the O2 molecule. Higher energy of UV split apart O2.

(iii) CFCs rise up in the stratosphere where UV radiation splits them releasing molecular chlorine (CI‐). It reacts with O3 and releases oxygen, so O3 gets depleted.

18. Ozone at the higher levels of the atmosphere is a product of UV radiations acting on oxygen (O2 ) molecules. The high energy UV radiations split apart some molecular oxygen (O2) into free oxygen (O) atoms. These atoms are very reactive and combine with the molecular oxygen to form ozone.

It shields the surface of the Earth from harmful ultraviolet (UV) radiations of the Sun.

Due to environmental pollution, the ozone layer began to deplete in the 1980s.

This was mainly due to the increasing use of synthetic chemicals like Chlorofluorocarbons (CFCs). 

These are used in refrigerants as coolant and in fire extinguishers. Due to depletion of the ozone layer, harmful UV rays can penetrate or enter our atmosphere.

These radiations are highly damaging to organisms. They can cause skin cancer in human beings, damage eyes (cause disease called cataract), decrease crop yield, disturb global rainfall, etc.

19. Following methods could be applied to reduce the accumulation of pesticides in our body.

(i) Minimize the use of pesticides 

(ii) Consuming washed fruits and vegetables

(iii) Developing vegetarian feeding habits

(i.e. feed upon plants as plants belong to lower trophic level so, they have less accumulation of insecticides, whereas organisms of higher trophic level have higher concentration of insecticides and pesticides).

20. We can reduce the problem of waste disposal by the following methods

• Recycling . The solid wastes such as paper, plastics, glass and metals, etc., are recyclable. So, waste paper can be sent to paper mills for reprocessing to form newspapers. The plastic articles can be melted and remolded again to make new articles.
• Biodegradable waste . The waste such as leftover food, fruits, animal dung, peels of vegetables can be converted into compost by burying them in a pit dug in ground and can be used as manure.

21. If all the waste is biodegradable, then there will be no accumulation of waste on the Earth and it would be a cleaner place to live.

But if this biodegradable waste is too large in amount then its slow degradation may lead to air pollution (due to release of gasses) as well as water and land pollution.

22. The two ways in which non-biodegradable substances would affect the environment are

(i) They make the environment poisonous and unfit for survival of living ol’ life.

(ii) They block the transfer of energy and minerals in the ecosystem.

23. Biodegradable materials are broken down by microorganisms present in nature into simple harmless substances. Non-biodegradable materials need a different treatment like heat and temperature for disposal and hence, both should be discarded in two different dustbins.

24. Effective segregation of waste as biodegradable and non-biodegradable is much easier to recycle. Biodegradable waste used to make manure can be made out of compost, whereas non-biodegradable waste could be recycled and reused for various purposes. Also effective segregation of wastes means that less waste goes to landfill, which makes it cheaper and better for people and the environment.

25. A pond ecosystem refers to a freshwater ecosystem where there are various organisms dependent on each other with the prevailing water environment for their nutrients and survival.

Phytoplankton—Zooplankton —Small fish—Big fish

There are two components of the pond ecosystem

(i) Abiotic . It includes water, dissolved minerals, oxygen and carbon dioxide. Sunlight is the main source of energy.

(ii) Biotic . It consists of phytoplanktons, zooplanktons, aquatic insects, fishes and other aquatic animals. These organisms are classified as producers, consumers and decomposers.

26. The waste generated in our house and measures for its disposal are given in the table below

27. Insecticides are non-biodegradable chemicals added to crop fields to stop the growth of insects infecting the crops. Modern insecticides are being developed keeping in mind the harm they cause to the environment and its components.

Biodegradable insecticides can be decomposed into harmless substances, which will subsequently be dispersed in their specific pathways and cause no pollution.

Non-biodegradable insecticides build up in the fat tissues of the body and pass on to organisms that feed on them. 

Hence, they accumulate along the chain resulting in significant amounts in the tissues of consumers at the highest trophic level.

The property of newly developed insecticide includes that it can easily get decomposed into simpler components by soil bacteria.

28. Mona follows a vegetarian diet along with milk products. She should be considered as occupying the third trophic level because the curd is prepared by the Milk cow/buffalo  by the action of bacteria, but the energy of the milk is getting transferred from cow to Mona, so Mona is at the third trophic level.

Grass      —— Cow (milk)  —— Human 

(First trophic) (Second trophic) (Third trophic)

29. Organisms which break down the complex organic compounds present in dead and decaying matter into simpler inorganic materials are called decomposers, e.g. certain bacteria and fungi.

Decomposers act as cleaning agents of the environment by decomposing dead bodies of plants and animals. They also help in recycling of materials, replenishment of soil’s nutrients, etc.

The consequence of their absence in an ecosystem can be disastrous. The dead bodies would persist for long, leading to their accumulation and thus, polluting the environment. The biogenetic nutrients associated with these remains will not be returned back to the environment.

As a result, all the nutrients present in soil, air and water would soon be exhausted and the whole life cycle of organisms would be disrupted. 

30. (i) Consumers are the organisms who derive energy by eating plants or other organisms as they cannot produce food on their own. Absence of primary consumers in nature would lead to enormous growth of plants and decline in the population of carnivore animals, who eat them. Hence, the whole food web will get distrupted.

(ii) The direction of energy transfer in following cases are as follows

• Primary consumer (grasshopper) to secondary consumer (frog).
• Producer (grass) to primary constnuer (deer).
• Primary consumer (deer) to secondary consumer (lion) 

31. (i) Yes, the impact of removing all the organisms in a  trophic level will be different [or dillörent trophie lex els. The lower trophic level ol’ an ecosystem has a greater number of individuals than the higher trophic levels. 

Removal of producers will affect all the organisms of successive trophic levels and it will threaten their survival. The removal of higher trophic level will lead to increase in organisms’ lower trophic level and the organisms at higher trophic level will die due to  shortage of food. 

(ii) No, removal of all organisms of a trophic   level will disturb the ecosystem. Killing of higher trophic level organisms will cause explosion in the population of lower

trophic level organism. This will adversely affect the ecosystem and the environment.

32. (i) The producers convert solar energy into chemical energy in the form of organic compounds. The primary consumers (herbivores) derive their nutrition from the producers. According to the energy transfer law, only 10% of energy is transferred from one trophic level to the other.

So, the energy that is captured by the producer does not revert back to the Sun and the energy transferred to the herbivores does not come back to the producers. It  just keeps on moving to the next trophic level in one direction. That is why the flow of energy in the food chain is always unidirectional 

(ii) A large number of pesticides and chemicals are used to protect our crops     pests and diseases. Sorne of these chemicals are washed clown from the soil, while some enter the water bodies. 

From the soil, they are absorbed by plants along with water and minerals and from the  water bodies, they are taken up by aquatic plants and animals. This is how these chemicals enter the food chain.

As these chemicals cannot decompose, they accumulate progressively at each trophic level. This increase in the concentration of harmful chemicals with each step of the food chain is called biomagnification. As human beings occupy the top level in any food chain, these chemicals get accumulated in our bodies in considerably high amounts causing diseases.

33. (i) Undesirable activities of man eliminate growth of organisms belonging to one or more trophic levels in a food chain. Thus, the food chain gets shortened, e.g. hunting tigers for their skin, etc. 

It causes imbalance in the functioning of the ecosystem and biosphere. If organisms of one trophic level are eliminated, the organisms prior to that trophic level will flourish and increase in number. Also, the organisms of the subsequent trophic level will sharply decrease, thereby creating an imbalance.

(ii) Vegetarian food chain is advantageous in terms of energy because it has less number of trophic levels. As we know, only 10% of the energy is transferred to the next trophie level in a food chain, so if a person is vegetarian then, he would have a maximum amount of energy by consuming producers or plants in a food chain.

34. Some harmful effects of agricultural practices on the environment are as follows

(i) Soil degradation . Extensive cropping causes loss of soil fertility. Also, over time it can lead to soil erosion and finally to desertification.

(ii) Pollution . Use of synthetic chemical fertilizers and nucl  pesticides leads to soil, water and air pollution.

(iii) Water shortage . Excess use of groundwater for agriculture lowers the water level. This results in acute water shortage at many places.

(iv) Biomagnification . The chemical pesticides, being  accumulate in organisms in increasing amount of each trophic level 

(v) Deforestation . Indiscriminate cutting of trees of agriculture has resulted in loss of habitat for wildlife.

Thus, it also causes damage to natural ecosystem.

35. Ozone is a triatomic molecule, i.e. made up of three atoms of oxygen joined together. Its molecular formula is O3. It can affect any ecosystem in the following ways

(i) It protects against ultraviolet rays if present in the stratosphere.

(ii) Ozone dissipates the energy of UV rays by undergoing dissociation followed by reassociation.

(iii) In the atmosphere, it is highly toxic and causes injury to mucous membranes, eye irritation and internal hemorrhages in animals and humans.

36, (i) Environmental pollution is an undesirable change in the physical, chemical or biological characteristics of the natural environment, brought about by man’s activities. This pollution may affect the soil, water or air. 

(ii) Differences between biodegradable and non-biodegradable pollutants are as follows:

37. Some daily life eco-friendly activities are

(i) Save a tree, use less paper . You can buy ‘tree-free’ 100% post-consumer recycled paper for everything from greeting cards to toilet paper. Paper with a high post-consumer waste content uses less pulp and keeps more waste paper out of landfills.

(ii) Opt bamboo for hardwood floors Bamboo is considered as an environmentally-friendly flooring material due to its high yield and the relatively fast rate at which it replenishes itself. It takes just 4-6 years for bamboo to mature, compared to 50-100 years for typical hardwoods. Also look for sources that use formaldehyde-free glues.

(iii) Reduce plastics, reduce global warming Unfortunately, plastics are made from petroleum, the processing and burning of which is considered one of (he main contributors to global warming, according to the EPA. In addition, sending plastics to the landfill also increases greenhouse gasses. 

Reduce, reuse and recycle our plastics are one of the best ways to combat global warming.

(iv) Use healthier paints Conventional paints contain solvents, toxic metals and Volatile organic compounds (VOCs) that can cause smog, ozone pollution and indoor air quality problems with negative health effects, according to the EPA. These unhealthy ingredients are released into the air, while we are painting, drying of paint and even after the paints are completely dry.

(v) Use compost Instead of using synthetic fertilizers, compost provides a full complement of soil organisms and the balance of nutrients needed to maintain the soil’s health. Healthy soil mininii.ses the population of  weeds.

38. Materials that retain for a long time in the environment, without getting by any natural agents, also causing harm to the environment are called non-biodegradable. 

Plastic cups are non-biodegradable and raised the concern towards hygiene, thus they were replaced by kulhads.

Kulhads are made up of clay on a large scale resulting in the loss of top fertile soil. It is replaced by disposable paper cups because the paper can be recycled, it is biodegradable and is eco-friendly material which does not cause environment pollution.

39. (i) There are 6 food chains that constitute the given food web. These are as follows

• Seeds— Mice — Foxes  
• Young trees — Mice — Foxes 
• Young trees — Rabbits — Foxes
• Grass — Rabbits — Foxes
• Grass — Rabbits — Snake
• Young trees — Rabbits — Snake

(ii) The primary consumers are the organisms who directly feed on the producers. In the given food web, rabbits and mice are the primary consumers, whereas foxes and snakes are the secondary consumers.

(iii) About 90% of energy is loss at each trophic level.

(iv) The foxes feed on the rabbits and mice. If all the foxes are killed then there will be no direct predator of rabbits and mice, hence the number of rabbits and mice (i.e. both are primary consumers) will increase in the given ecosystem, which will disturb its balance.

(v) Accumulation of toxic non-biodegradable substances increases at each trophic level. It is least in organisms of first trophic level (i.e. seeds), young trees and grass and highest in organisms of third trophic level (i.e. foxes and snakes).

40. (i) The green plants in a terrestrial ecosystem capture about 1% of the energy of sunlight (light energy). They convert it into food energy (chemical energy).

Therefore, if 10,000 J solar energy falls on green plants in a terrestrial ecosystem, only 1% of solar energy, i.e. 100 J will be converted into energy.

(ii) Decomposers are not included in the food chain as they act at every trophic level of the food chain.

(iii) Primary consumer are those organisms who directly feed on plants; e.g. herbivores 

Primary carnivores are those organisms who feed on plant-eating animals e.g. snakes.

(iv) Decrease in energy at higher trophic levels (according to 10% law) is one of the reasons that limits the trophic levels in a food chain.

(v) Owl is placed at the highest trophic level in the given food web, therefore the accumulation of non-biodegradable toxic materials are found to be highest in them due to biomagnification.

41. (i) The longest food chain consists of a maximum five trophic levels.     

(ii) Rabbit is a herbivore as it feeds on plants directly. Its role in the given food web is to transfer the energy from  producers to carnivores.

(iii) The significance of food web is as follows 

• Food chains provide pathways for availability of food. 
• It allows endangered populations to grow in size. 

(iv) Sun or solar energy is the ultimate source of energy for the Earth. Only plants can utilize this energy to make their on food.

(v) When a predator for a particular organism decreases in number, the organisms start increasing in number.

As the animals which used to feed on them decrease in number, therefore, the population of those organisms increases.

42. (i) Substances that are responsible for depletion of the ozone layer or breakdown of ozone molecules are known as ozone depleting substances.

e.g. CFCs, halogens, nitrous oxide, CCl4 and CH4 are ozone depleting substances responsible for ozone layer depletion.

(ii) Atomic oxygen is highly reactive. It combines with molecular oxygen to form ozone.

(iii) Ozone layer is found in the stratosphere around 15-30 km above the Earth’s surface.

(iv) Ozone is a triatomic molecule made up of three atoms of oxygen (03). It is present in the atmosphere as an ozone layer shield that protects us from high energy UV radiations. 

So, it is known as good ozone whereas near the surface of earth ozone act as a highly poisonous gas. Hence,  bad ozone.

(v) Cancers, mutations, effects on eyesight, global warming, weakening of the immune system, etc., are some adverse effects of ozone depletion.

Final Words

From the above article, you have practiced Class 10 chapter 15 our environment notes and questions. We hope that the above-mentioned notes and Q & A for term 2 will surely help you in your exam. 

If you have any doubts or queries regarding Class 10 chapter 15 our environment notes and questions, feel free to reach us and we will get back to you as early as possible.

Click Below To Learn Science Term-1 Syllabus Chapter wise MCQs

• Chapter 1: Chemical Reactions And Equations MCQ
• Chapter 2 Acids Bases and Salts mcq
• Chapter 3 Metal and Non-metals mcq
• Chapter 6: Life Process MCQ
• Chapter 10: Light: Reflection And Refraction MCQ 
• Chapter 11: Human Eye And Wonderful World MCQ

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Our Environment

These notes are based on the chapter Our Environment from class 10 science NCERT book and CBSE syllabus.

Our surrounding is called environment. The clasroom, playground and garden in your school make the environment of your school. Even your teachers and fellow students are part of that environment. Similarly, the houses in your neighbourhood, neighbours, stray animals, trees, park, etc. make the environment of your neighbourhood.

• Components of ecosystem
• Food chain and food web
• Ozone layer and its depletion
• Problem of waste disposal

This is a system of interdependencies among various living beings and non-living things in a given habitat. Every component of an ecosystem is dependent on each other.

To understand this, you can take the example of a garden. The plants in the garden depend on soil, air and water. Soil, in turn, depends on decomposition of plants to get back nutrients. Many creatures depend on plants for food and shelter. Many of these creatures help plants in pollination and dispersal of seeds.

Components of Ecosystem

An ecosystem has two types of components, viz. biotic component and abiotic component.

Abiotic Component

All the non-living things make the abiotic component of an ecosystem. Air, water and soil are abiotic components.

• Air provides oxygen ( for respiration ), carbon dioxide ( for photosynthesis ) and other gases for various needs of living beings.
• Water is essential for all living beings because all the metabolic activities happen in the presence of water.
• Soil is the reservoir of various nutrients which are utilised by plants. Through plants, these nutrients reach other living beings.

Biotic Component

All living beings make the biotic component of an ecosystem. Different types of biotic components are as follows:

Producer: Green plants play the role of producers because they prepare their own food.

Consumer: Animals and other living beings play the role of consumers because they take food (directly or indirectly) from plants.

Decomposer: Bacteria and fungi play the role of decomposers, as they decompose dead remains of plants and animals so that raw materials of organisms can be channelized back to the environment.

A food chain is a simple representation of transfer of energy from the sun to different biotic components of an ecosystem. Sun is the ultimate source of energy, because most of the sources of energy on earth have got energy from sun. Green plants convert solar energy into chemical energy during photosynthesis. When an animal takes food, this energy is supplied to the animal and the process goes on. A simple food chain can be shown as follows:

Producer → Primary Consumer → Secondary Consumer

Real life cannot be as simple as a food chain shown above. For a given prey, there can be many predators. For example, grass is eaten by many animals. A goat is eaten by many carnivores. In any ecosystem, there can be many food chains which are interlinked at various levels. Thus, many food chains form a network which is called food web.

Transfer of Energy through a food chain

Different levels in the food chain are called trophic level . Out of the energy consumed by an organism at a particular trophic level, 90% is utilised for its own need and rest 10% is left for the organism of the next trophic level. So, very little energy is left for the organism which is at the tertiary level.

Let us assume that a green plant makes 100% energy in the form of chemical energy. 90% of this energy would be utilised for its own purpose. This would leave just 10% energy for the primary consumer.

Now, primary consumer shall also utilize 90% of energy which was consumed by it. This would leave just 1% energy for (10% of 10 = 1) for the secondary consumer.

By this logic, the tertiary consumer would get just 0.1% of energy which was originally made by the green plant. This is the reason, there can be just one or two organisms at the top of the food pyramid.

This explains why the population of producers is always the largest in an ecosystem, followed by the population of herbivores and then that of carnivores. Moreover, an herbivore needs to eat many plants in its lifetime to fulfill its energy need. Similarly, a carnivore needs to eat many herbivores in its lifetime.

Balance in the Ecosystem

There is a delicate balance in an ecosystem, as far as number of organisms at a particular trophic level is concerned. An increase or decrease in population of any organism can disturb this balance.

What will happen if all the deer are killed in a jungle?

Let us take a hypothetical example to understand this. If all the deer are killed in a jungle, the lions would be left with no food. This would endanger the existence of lions. Once the lions and deer would be finished, it would result in population explosion of green plants.

What will happen if all the lions are killed in a jungle?

If all the lions die in a jungle, it would create another problem. Since no lion would be left to kill the deer, the population of deer would increase substantially. This will finish off all the green plants and finally even the deer would be left with no food for them.

Biodegradable Substance: Substances which can be decomposed by microorganisms are called biodegradable substances. All the organic substances are biodegradable.

Non-biodegradable: Substances which cannot be decomposed by microorganisms are non-biodegradable. All inorganic substances are non-biodegradable. Many synthetic substances are also non-biodegradable.

Ozone Layer Depletion

Ozone layer.

The stratosphere is composed of ozone and is also called ozone layer. It prevents ultraviolet radiations from entering the earth's surface.

Chlorofluorocarbons

Fully or partly halogenated form of hydrocarbons is called chlorofluorocarbon. They contain only carbon, hydrogen, chlorine and fluorine. They are used in refrigerants and aerosols. They damage the ozone layer.

Ozone layer is also known as stratosphere. When ultraviolet radiations act on oxygen, the oxygen gets converted into ozone.

Ozone layer works like a protective shield for living beings. The ozone layers wards off harmful ultraviolet radiations from the sun.

Effect of CFCs

Use of CFCs ( Chlorofluorocarbon ) has damaged the ozone layer. As a result, the ozone layer has become thinner at certain parts.

Tackling ozone layer depletion

In 1987, the UNEP (United Nations Environment Programme) succeeded in forging an agreement among different nations to freeze the CFC production at 1986 level. Later, an agreement was signed among different nations to phase out CFCs. It is important to note that CFC is used in refrigerators and aerosol spray. India is also a signatory of that agreement and thanks to the efforts by the United Nations and different environmentalists, the CFC emission has been put under some control.

Problems of Waste Disposal

During our day to day activities, we produce lot of waste. While some of the waste is biodegradable, a large chunk is composed of non-biodegradable substances. Plastic waste is a serious concern because plastic is non-biodegradable. We need to respect our environment and find out ways to reduce the burden on our environment.

• Ecosystem: System of interdependence among living and non-living in a given habitat.
• Biotic Components: All the living things in a given habitat comprise biotic component of ecosystem
• Abiotic Components: All the non-living things in a given habitat comprise abiotic component of ecosystem
• Environment
• Chapter Summary
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Assignments Class 10 Science Our Environment

Please refer to Assignments Class 10 Science Our Environment Chapter 15 with solved questions and answers. We have provided Class 10 Science Assignments for all chapters on our website. These problems and solutions for Chapter 15 Our Environment Class 10 Science have been prepared as per the latest syllabus and books issued for the current academic year. Learn these solved important questions to get more marks in your class tests and examinations.

Our Environment Assignments Class 10 Science

Very Short Answer Type Questions 

Question. Name two natural ecosystem. Answer : Pond ecosystem and forest ecosystem.

Question. Which component of sunlight is used for the formation of ozone? Answer : Ultra violet radiation.

Question. What is bad Ozone? Answer : Ozone at ground level is deadly poisonous and is called as bad Ozone.

Question. Name 4 abiotic components of any ecosystem. Answer : Temperature, rainfall, wind, soil.

Question. Name two artificial ecosystem. Answer : Garden and crop-field.

Question. Name the natural cleansing agent in an ecosystem. Answer : Decomposers, scavengers

Short Answer Type Questions 

Question. Minimum energy is available at highest trophic level while maximum energy is at lowest level. Explain. Answer : Since non-biodegradable substances cannot be broken down into simpler forms hence they keep on accumulating in nature causing ecological imbalance. 

Question. Give one advantage and one disadvantage of Ozone. Answer : Advantage of Ozone–When it is in the stratosphere it does not allow the ultraviolet radiations to reach the earth, as UV radiations cause skin cancer and cataract. Disadvantage of ozone: On ground level ozone is poisonous gas.

Question. Aquarium requires regular cleaning whereas lakes normally do not. Why? Answer: Normally a lake has more diverse forms of life and hence a larger number of food chains. This leads to natural cleaning. Thus, the ecosystem is more stable. The aquarium has a very limited number of food chains and unable to sustain itself. But, sometimes there is excessive growth of algae in lake. Then it also needs to be cleaned.

Question. Why is plastic not degraded by bacteria? Answer: Plastic is not degraded by bacteria because they do not have enzymes to degrade plastic.

Question. Using Kulhads as disposable cups to serve tea in trains, proved to be a bad idea. Why? Answer: Making Kulhads on large scales leads to the loss of top soil. 

Question. DDT has entered food chain. Which food habit is safer- vegetarian or nonvegetarian? Answer: Vegetarian habit is safer. Being closer to producers, less DDT will accumulate in our body. Bio magnification leads to higher level of DDT in higher trophic levels.

Question. Why are green plants called producers?  Answer : Green plants can prepare complex organic matter as food from simple inorganic substances like CO 2 , H 2 O in presence of sunlight and chlorophyll. They produce food and hence called producers.

Question. What is biological magnification? Answer : The accumulation of chemicals in the bodies of the organism that belongs to the top most tropic level is called biological magnification. As human beings occupy highest trophic level its maximum concentration was found in human beings only, which resulted in neurological disorders due to damaging of CNS (Central Nervous System).

Question. What are the problems caused by the non-biodegradable waste that we generate? Answer : Non-biodegradable waste doesn’t decompose under the action of bacteria and other microorganisms. • When these substances, e.g., polythene, plastics are buried under soil render that area barren and leads to soil pollution. • These wastes don’t burn completely in presence of oxygen and release toxic gases which causes air pollution. • The substances may be harmful on accumulating in food chain like DDT due to biomagnification.

Question. Why is damage to ozone layer a cause for concern? What steps are being taken to limit this damage? Answer : Ozone layer doesn’t allow harmful ultra violet rays of the sun to reach the earth’s surface. In order to stop further depletion of ozone layer we must scale down the use of CFC’s in form of aerosols, refrigerants etc and check their release in the atmosphere. Moreover stress should be laid on using eco-friendly techniques and proper disposal of toxic material.

Question. Why are bacteria and fungi called decomposers? List any two advantages of decomposers to the environment. Answer : Bacteria and fungi are called decomposers as they break down the dead remains and waste of organisms. They convert the organic complex substance into simple inorganic substances that go into the soil and are used up by plants. Two advantages of decomposers: 1. They return the components back to nature and creates balance in the environment. 2. They act as cleansing agents of the atmosphere.

Question. (a) Distinguish between producers and decomposers. (b) Classify the following as producers and decomposers. Green plants, bacteria, fungi, blue-green algae.

Answer : (a)

Question. Why decomposers are necessary in environment? Answer : Decomposers act on all biodegradable substances and break them into simple inorganic materials and maintain the balance of materials in the ecosystem and cleanse the environment.

Question. Why is the ozone layer getting depleted at the higher levels of the atmosphere?  Answer : Ozone is present at higher levels of the atmosphere where CFC – Cholorofluorocarbons reach, chlorine separates and acts on O 3 to split it into O 2 and (O). The conditions required to do this are available at higher levels i.e., clouds and sunlight.

Question. Give one example of grassland ecosystem and one example of pond ecosystem. Answer : Grass land Ecosystem: Grass → grasshopper → frog → snake → peacock. Pond Ecosystem : Blue-green algae → small fish → big fish → birds

Question. Energy flow in a food chain is unidirectional. Explain. Answer : The energy from the sun flows into autotrophs and it passes to herbivores and then to carnivores. The energy does not revert from autotrophs to the solar input or from herbivores back to autotrophs. Hence the flow is unidirectional.

Question. Name any two abiotic components of an environment.  Answer : Water, air.

Long Answer Type Questions 

Question. What is ozone and how does it affect any ecosystem? Answer : Ozone is a molecule of oxygen with 3 atoms its formula is O3. The ultra violet radiations split oxygen into free oxygen atoms, these atoms combine with oxygen molecules to form ozone.

O 2  —→UV rays  O + O

O 2 + O ⎯⎯→ O 3 (Ozone)

Ozone in Ecosystem: At ground level ozone is poisonous but at higher level it is very useful as it protects all living organisms from harmful UV radiations of the sun. It doesn’t allow the ultra violet radiations to enter the surface of earth. The UV radiations cause ionizing effect that leads to skin cancer in human beings.

Question. It is the responsibility of the government to arrange for the management and disposal of waste. As an individual you have no role to play. Do you agree? Support your answers with two reasons. Answer: I do not agree. As an individual, I also have the responsibility and can contribute in the following ways:- (i) Cut down waste generation. (ii)Make compost pit for bio degradable waste. (iii) Recycle non biodegradable waste.

Question. Look at the following figures. Choose the correct one and give reason for your answer.

Answer: Fig. “A” is correct. • In an ecosystem, the number of individuals at producer level is maximum. This number reduces at each successive level. Therefore, the shape is a pyramid with broader base and tapering apex. • On an average 10% of the food changes into body mass and is available for the next level of consumers . 

Question. How will accumulation of bio degradable waste effect our environment? Answer: Accumulation of bio degradable waste will: (a) Not let minerals return to mineral pool. (b) Become site of pest breeding.

Question. How can you help in reducing the problem of waste disposal? Give any two methods. Answer : To reduce the problem of waste disposal we can (i) Segregate the bio-degradable waste from non-biodegradable waste before dumping it. (ii) Remove all materials which can be recycled and send it for recycling. e.g., paper, glass, metal, rubber.

Question. Enlist various categories of consumers giving examples of each. Answer : The various categories of consumers are: Herbivores — Grass eating animals, e.g., deer, rabbit. Carnivores — Flesh eating animals, e.g., tiger, lion. Omnivores — Animals that eat both plants and other small animals i.e., flesh e.g., crow, human being. Parasites — Those organisms which depend on other living organisms and harm them for food, e.g., lice, tapeworm. Saprophytes — Organisms that depend on dead and decaying matter for their food, e.g., fungi, bacteria.

Question. What three informations are obtained from the energy flow diagrams? Answer : The information we get are: (i) The energy flow is unidirectional, it flows from sun → autotrophs → herbivores → carnivores → decomposers (ii) The flow of energy is 10% i.e., 90% of the energy is used by a given level of food chain for metabolic activities. (iii) The unwanted chemicals like pesticides gets accumulated in the highest organism in the food chain.

Question. What will happen if we kill all the organisms in one trophic level? Answer : If all the organisms in one trophic level are killed then all the organisms of next trophic level which are dependent on these are killed. Next trophic levels will not get food to eat and the entire food chain gets disturbed. At the same time the organisms at the lower trophic level will reproduce and the population will increase in abundance there by disturbing the ecosystem.

Question. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem? Answer : The impact of removing all the organisms in a trophic level will be same. If the organisms of any trophic level be removed it will certainly damage the ecosystem. For example, Grass → Grass hopper → Frog → Snake → Peacock In this if all grasshoppers are killed/removed frogs will strive and grass will reproduce in abundance. If snakes are removed then the number of frogs will increase which will disturb the entire ecosystem.

Question. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem? Answer : The pesticides and chemicals are absorbed by plants from the soil and enter the food chain. Being non-biodegradable they accumulate progressively at each trophic level. As human occupy the top level of any food chain, the maximum concentration of chemicals is found in our bodies. This is called biological magnification. The level of magnification will be different at different trophic levels, the maximum concentrations will be at the highest trophic level and the chemical will be less at lower trophic levels.

Question. Explain the interlink of biotic and abiotic factors in any ecosystem. Answer : In an ecosystem biotic and abiotic factors are interdependent and interlinked. For example: The grass in grassland will grow only if it gets soil which can hold water and gets sunlight with proper temperature hence the grass grows in a place which has all abiotic factors responsible for its growth but in desert these abiotic factors are not available for the growth of grass.

Question. Why are some substances biodegradable and some non-biodegradable? Answer : Substances which can be decomposed and broken down to simpler substances by micro-organisms acting on it is called bio-degradable and those substances which cannot be acted upon by micro-organisms and are not broken down into simpler substances are called non-biodegradable substances.

Question. Give any two ways in which bio-degradable substances would affect the environment. Answer : Two ways in which bio-degradable substances would affect the environment are: (i) During decomposition of the substances lot of foul smell spreads in the surrounding areas. (ii) The place where these bio-degradable substance are present with some moisture becomes breeding ground for insects like mosquitoes, housefly which are vectors in carrying parasites that cause different diseases.

Question. Give any two ways in which non-biodegradable substances would affect the environment. Answer : (i) The non-biodegradable substances get accumulated and doesn’t get decomposed hence it remains in the ecosystem and causes pollution, chokes the system of many animals and kill them. (ii) These substances due to accumulation cause water and soil pollution e.g.,pesticides, detergents, polythene.

Question. Explain the formation of ozone layer and its importance. Answer : Ozone is formed when high energy ultra violet radiations split oxygen molecule into oxygen atoms. The oxygen atom combines with oxygen molecules to form a new molecules with three oxygen atoms named ozone.

O 2  + O ⎯⎯→ O 3 (Ozone)

Importance of Ozone: It is very protective when present in stratosphere it does not allow the harmful ultra violet radiations to enter the earth’s surface which can cause skin cancer in human beings.

Value Based Question

Question. All eco-club students collect the vegetable peels from canteen and use them in compost pit made in their school. (a) Name items that can be added in compost pit other than vegetable peels. (b) What type of reaction is seen in the pit? (c) State the values seen among eco-club members. Answer : (a) Students can use leftover food and fruit peels, dried leaves. (b) Fermentation i.e., anaerobic decomposition. (c) The eco-club students show team work, collaborative work and good behaviour.

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Our Environment of Class 10

Our environment .

Man has always inhabited two worlds. One is the natural world of plants, animals soil, air and water,of which we are also a component while, the other is the world of society that we have created ourselves using science, technology and political organization. Both of these are essential for our survival but integrating them sometimes causes alterations in the environment. Thus, to ensure a sustainable future for ourselves and future generations. We need to know about out environment, its working and our role in its working, protection and management.

Environment

Environment is defined as the surroundings in which the organism lives.

Environmental science is the systematic, scientific study of our environment as well as our place in it. This study gives us the scientific foundations to understand certain important areas of economic importance that are essential for the existence, such as agriculture, forestry and fisheries. This study also gives us a basis for predicting, preventing and finding remedial measures to minimize pollution. It helps us to understand the consequences of the human intervention in the natural processes, such as construction of dams on rivers, diversion of rivers, cutting of forests, etc.

The environment may be the physical environment, the chemical environment or the biological environment. Thus, the environment has two components

Biotic component: It is the living component of the environment. All the living organisms are included in it.

Abiotic component: It is the non-living component of the environment. The abiotic components are the physical factors such as:

• Climatic factors like light, wind, humidity, temperature, precipitation etc.
• Edaphic factors like soil texture, minerals, pH, topography etc.

At the time of its origin, earth was a fire ball having a temperature of 5000-6000°C at its outer surface. As it cooled, the simple molecules like water (in the form of vapours), methane, helium and ammonia came into existence. At that time these gases were very hot and the molecules were moving at a very high speed. Lighter gases such as hydrogen and helium escaped into the atmosphere. No oxygen was present at that time. As the autotrophs were developed, the oxygen was added to atmosphere by their photosynthetic activity. Due to the volcanic eruptions, most of the minor constituents rich in sulphurous gases entered into atmosphere.

The planet earth along with the atmosphere i.e., air, land (lithosphere) and water (hydrosphere) that sustains life is called biosphere.

It extends downward into the oceans to depth of about 10.67 km and vertically into the air to about 10km where life is found to exist.

At a height between 15 to 60 km in the upper atmosphere, a layer of ozone (O3) gas exists. This ozone layer surrounds the earth as an umbrella and absorbs the ultraviolet radiations coming from the sun to the earth as they are very harmful for living organism surviving on earth. An ionic layer is also present above this ozone layer which reflects the radio waves.

THE CONTENT OF PRESENT ATMOSPHERE

Nitrogen 78 per cent

Oxygen 21 per cent

Carbon dioxide 0.032 to 0.047 per cent

Other gases 0.07 per cent

Water vapours A very less amount and its percentage is variable.

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Our Environment

Table of Contents

What is the Environment?

Types of ecosystem, importance of environment, impact of human activities on the environment.

An Environment is everything that is around us, which includes both living and nonliving things such as soil, water, animals and plants, which adapt themselves to their surroundings. It is nature’s gift that helps in nourishing life on Earth.

The environment plays an important role in the existence of life on the planet earth. The word Environment is derived from the French word “Environ” which means “surrounding.” An ecosystem refers to all the living and non-living things present in the environment and it is a foundation of the Biosphere, which determines the health of the entire planet earth.

Ecology and Environmental science are the branches of life science, which mainly deal with the study of organisms and their interactions with other organisms and their environment.

There are two main types of ecosystems . Listed below are the types and examples of the ecosystem.

• Natural ecosystem – It is a naturally produced biological environment found in nature. It includes deserts, forests, grasslands, lakes, mountains, ponds, rivers, oceans, etc.
• Artificial ecosystem – It is an artificial environment which is created and maintained by man. It includes an aquarium, crop fields, gardens, parks, zoo, etc.

The components of the environment are mainly divided into two categories.

• Biotic environment–It includes all living organisms such as animals, birds, forests, insects, reptiles and microorganisms like algae, bacteria, fungus, viruses, etc.
• Abiotic environment– It includes all non-living components such as air, cloud, dust, land, mountains, rivers, temperature, humidity, water, water vapour, sand, etc.

Also refer:  Biotic and Abiotic components

Environment plays an important role in healthy living and the existence of life on planet earth. Earth is a home for different living species and we all are dependent on the environment for food, air, water, and other needs. Therefore, it is important for every individual to save and protect our environment.

There are different types of human activities which are directly attributed to the environmental disasters, which include- acid rain, acidification of oceans, change in the climate , deforestation, depletion of an ozone layer, disposal of hazardous wastes, global warming, overpopulation, pollution, etc.

Also read:  Environmental Issues and Solutions

Important Questions

• What is a Natural Ecosystem?
• Why is the ecosystem important?
• Why should we conserve biodiversity short answer?

This was a brief introduction to Our Environment. Stay tuned with BYJU’S to learn more about Environment, Environmental Issues, Ecosystem, Components of the Environment and other related topics at  BYJU’S Biology

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