Class 10 Our Environment

The rapidly surfacing environmental issues are being constantly debated on a global level as our planet earth is struggling with climate change, global warming, ozone depletion, water shortage, pollution, waste management, and many more others. Through a dedicated chapter in NCERT Class 10 Science syllabus, students are familiarized with the essential factors which are significantly impacting our environment as well as the different ways they are causing harm to our planet. This chapter of Class 10 Our Environment’, explains the importance of a healthy environment, environmental issues, how several components interact in the environment and affect it, amongst others. If you are studying this chapter and need a thorough summary, this blog has collated Class 10 Our Environment notes covering the major topics and important exam questions in reference to this chapter. 

Environment

The word ‘environment’ is derived from the French word ‘Environia’ which means ‘Surrounding’. It is often interchangeably used with nature and surroundings, but an array of different components form an environment. Everything around us, including both living and nonliving components like soil, animals, plants, microbes, etc. collectively form our environment. 

While going through the notes for Class 10 Our Environment, you must also remember that the living and non-living components in an environment adapt themselves according to the surroundings and play a significant role in maintaining the balance of the environment which is very important in sustaining life on planet earth.  

Ecosystem

The chapter of Class 10 Our Environment notes also covers the concept of the Ecosystem. When all the living and nonliving components like plants, animals, human beings, soil, air, etc. interact with each other and maintains the balance in nature, it forms an ecosystem in the environment. Also, it is important to note that whether they are natural or artificial, an ecosystem is a combination of biotic and abiotic components that interacts with each other in a surrounding and contributes to maintaining the environmental balance. 

Examples of Ecosystem
A garden is an ecosystem that has biotic components and abiotic components that interact with each other and makes collective growth. 
Forests, lakes, oceans, ponds, etc. are natural ecosystems that exist in nature on their own. On the other hand, artificial ecosystems are usually aquariums, gardens, crop fields, etc. which are man-made.

Components of Ecosystem

According to the class 10 Our Environment chapter, there are two components in an ecosystem. These are:

1. Biotic components: these include three major types of organisms:
   • Producers: Organisms like green plants and certain types of bacteria make their food using the radiant energy of the sun. Thus, when an organism makes the organic compound using the inorganic substance, it is called producers. Example: Green plants produce their food by the method of photosynthesis.
   • Consumers: When an organism depends on the producers for its nourishment or consumes the food directly or indirectly from the producers, then such organisms are called consumers. It can be classified into herbivorous, carnivorous, omnivores, and parasites. Let’s discuss each of these 4 types in brief:
     • Herbivores: These are animals or creatures that obtain their nourishment by directly eating the producers (or plants). Herbivores are often referred to as first-order consumers. Herbivores include animals such as deer, rabbits, rats, squirrels, goats, and cattle.
     • Carnivores: These are organisms (animals) that eat other creatures. As a result, carnivores feast on herbivore meat. These are also referred to as main carnivores or second-order consumers. Snakes, wild cats, jackals, frogs, certain birds, and fishes are common examples. There are creatures that hunt main carnivores. They are referred to as second or third-order customers. Second-order carnivores include owls, peacocks, tigers, and lions, among others, and can be devoured by third-order carnivores. Top carnivores are carnivores that are not preyed upon further. The lion, for example, is a top carnivore.
     • Omnivores: Omnivores are creatures that consume both plants and animals. Humans are prominent examples of omnivores since they consume both plants and animals (plant products like pulses, grams, oilseeds, fruit, etc., and animal products like milk, meat, egg, etc.).
   • Decomposers: Organisms that get the nutrient by decomposing the dead plants and animals are called decomposers. A decomposer breaks the complex organic substance into simple inorganic substances that can be used by other organisms. Example: Bacteria, fungi, etc. 
2. Abiotic Components: These are non-living components of an ecosystem and include the physical environment Iike:
   • Soil texture, terrain, water, and air are all edaphic variables.
   • Carbon dioxide, nitrogen, oxygen, water, phosphorus, sodium, potassium, and calcium are examples of inorganic substances. These are engaged in the material cycle in the environment.
   • Proteins, carbohydrates, and lipids are examples of organic molecules. These make up the majority of the living organism and connect the abiotic and biotic components.

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Food Chains and Webs

Class 10 Our Environment notes also covers the concepts of food chains and food webs which are integral to the smooth functioning of any ecosystem. Organisms feed on one another for fulfilling their nourishment needs in the environment. These organisms constitute the biotic levels and form a food chain. Thus, a food chain can be described as a series of organisms wherein one organism eats another one. 

E.g. Grass –> Deer –> Lion, Rat –> Cat –> Snake –> Eagle
Interconnection of different food chains forms a food web. 

Every step of the food chain forms a trophic level that includes producers at the first level, primary consumers at the second level, secondary consumers at the third level, and tertiary consumers at the fourth level.

Flow of Energy

While studying Class 10 Our Environment notes, you must also go through the concept of the flow of energy in any ecosystem and environment. For all living organisms, food is the primary source of energy. When different components of the environment interact with each other, it creates a flow of energy that transmits from one component to another. 

E.g. Autotrophs or producers capture the energy of the sunlight to produce food. This energy flows from autotrophs to heterotrophs and decomposers in a food chain, making a flow of energy.

However, during the transmission, the energy gets converted into other forms, and some energy gets lost in the transmission that cannot be used again. A flow of energy moves progressively throughout the trophic level and will always be unidirectional. It means that autotrophs cannot give back the energy to the sun, and the same applies to heterotrophs and decomposers.

Trophic Levels

Trophic levels refer to the various stages in the food chain where food (or energy) is transferred. In a food chain, the quantity of energy transferred from one trophic level to the next trophic level decreases gradually. As a result, only 10% of energy is transmitted to the next trophic level, while 90% of energy is utilized by the current trophic level in its life activities.

The following are the several trophic levels:

• The first trophic level is made up of plants or producers.
• The second trophic level is formed by herbivores or main consumers.
• The third trophic level is made up of carnivores or secondary consumers.
• The fourth trophic level is made up of large carnivores or tertiary consumers who feed on small carnivores.

Ozone Layer

Moving further to the summary of the next sub-unit in Class 10 Our Environment notes, the topic of the Ozone Layer is an imperative one to understand. Ozone is a molecule that contains three atoms of oxygen. While it is a deadly poison at the ground level, it plays a significant role at the higher levels of the atmosphere in protecting the earth. The ozone layer acts as a shield or a protective blanket that protects the earth’s surface from the harmful ultraviolet radiation of the sun.

Ozone serves an important purpose. It protects the earth’s surface from the Sun’s ultraviolet (UV) radiation. This radiation is extremely harmful to creatures; for example, it has been linked to skin cancer in humans. Ozone is a byproduct of UV light acting on oxygen (O₂) molecules at higher altitudes of the atmosphere. Higher intensity UV rays disintegrated some molecular oxygen (O₂) into free oxygen (O) atoms. These atoms then combine with the molecular oxygen to form ozone as shown:

O₂   = O + O

O + O₂  = O₃  (Ozone)

Depletion of Ozone Layer

The ozone layer is a protective blanket that surrounds the Earth and absorbs the majority of the Sun’s damaging U.V. (Ultraviolet) radiation, safeguarding the Earth’s living creatures from health dangers such as skin cancer, cataracts in the eyes, weakened immune systems, plant damage, and so on. The increased use of CFCs (chlorofluorocarbons) in appliances like refrigerators and fire extinguishers affects the ozone layer. It is one of the reasons that are responsible for the depletion of the ozone layer. Thus, many modern-day appliances are CFC-free, which helps in sustaining the level of the ozone layer in the atmosphere.

The OZONE HOLE was named after the discovery of a decrease in the thickness of the Antarctic ozone layer in 1985. The thinning of the ozone layer is called ozone depletion. Chlorofluorocarbons (CFCs), oxides of nitrogen, methane, carbon tetrachloride, and chlorine are ozone-depleting substances. Skin cancer in humans and animals, as well as severe plant damage, would result from ozone layer depletion.

Biodegradable Wastes

Biodegradable substances are those that can be broken down by biological processes. These chemicals degrade as a result of the activities of fungus, bacteria, and other living creatures. Temperature and sunshine are also key factors in the breakdown of biodegradable compounds. Food waste, tree leaves, urine, and fecal matter, sewage agricultural residue, paper, wood, fabric, cow manure/dung, and so on.

Non-Biodegradable Wastes

Non- biodegradable wastes are those substances that do not degrade as a result of biological processes. These substances can exist as solids, liquids, or gases. These chemicals are inactive and merely stay in the environment for an extended period of time, or they may harm the various ecosystem components. (anewcareer) As an example: DDT, insecticides, pesticides, mercury, lead, arsenic aluminum, plastics, polythene bags, glass, and radioactive wastes are among them. These non-biodegradable wastes are important environmental pollutants.

Garbage Management

Careless waste disposal creates different environmental problems. Categorized as biodegradable or non-biodegradable, waste causes a hazardous impact on the surroundings when left undisposed. The difference between the two types of waste is that when a substance is easily broken down by biological processes and decomposed completely, it is said to be biodegradable but when a substance is not broken by the biological processes or decomposed it is said to be non-biodegradable.  

With the increase in garbage and waste materials, it is important to manage waste disposal by various means. The best ways to facilitate garbage management are through methods like biogas plants, sewage treatment plants, land fillings, recycling, etc. 

Class 10 Our Environment Important MCQs

1. Which group of organisms are not the constituents of a food chain?

i. Grass, lion, rabbit, wolf

ii. Plankton, man, fish, grasshopper

iii. Wolf, grass, snake, tiger

iv. Frog, snake, eagle, grass, grasshopper

A. i and iv

B. i and ii

C. i and iii

D. ii and iii

2. The percentage of solar radiation absorbed by all the green plants for the process of photosynthesis is about:

A. 5%

B. 6%

C. 1%

D. 10%

3. The decomposers in an ecosystem

A.convert inorganic material, to simpler forms

B.do not breakdown organic compounds

C.convert organic material to inorganic forms

D.convert inorganic materials into organic compounds

4. Accumulation of non-biodegradable pesticides in the food chain in an increasing amount at each higher trophic level is known as

A. pollution 

B. accumulation 

C. eutrophication 

D. biomagnification 

5. In an ecosystem, the 10% of energy available for transfer from one trophic level to the next is in the form of

A. chemical energy 

B. Heat energy 

C. light energy 

D. mechanical energy 

6. Organisms that synthesize carbohydrates from inorganic compounds using radiant energy are called

A. carnivores

B. producers 

C. decomposers 

D. parasites 

7. Organisms of a higher trophic level that feed on several types of organisms belonging to a lower trophic level constitute the

A. ecological pyramid 

B. food web 

C. food chain 

D. ecosystem 

8. At which trophic level is the maximum energy available?

A. T1

B. T2

C. T3

D. T4

9. The problem caused due to ozone hole is

A. acid rain 

B. earthquakes 

C. damage due to UV radiations and rays 

D. chemical pollution 

10. In a given food chain if the amount of energy at the fourth trophic level is 6 kJ, what will be the energy available at the producer level?

A. 600 kJ

B. 60 kJ

C. 300 kJ

D. 6000 kJ

Answers

1. D
2. C
3. C
4. D 
5. A
6. B
7. B 
8. A
9. C
10. D 

Class 10 Our Environment: Important Questions and Answers 

Class 10 Our Environment: Question Bank 

Now that you have gone through the Class 10 Our Environment notes, here are some important exam questions you must practice:

1. Explain the difference between a food web and a food chain?
2. Define biological magnification.
3. Why is the ozone layer important for organisms?
4. What do you understand by biodegradable substances and non-biodegradable substances? 
5. Why are biodegradable substances important for the environment?
6. How is the increase in demand for energy affecting our environment adversely?
7. Why are bacteria and fungi called decomposers? List any two advantages of decomposers to the environment.
8. How is ozone formed in the upper atmosphere? Why is the damage of ozone layer a cause of concern to us? State a cause of this damage. 
9. Construct an aquatic food chain showing four trophic levels.
10.  Explain the phenomenon of “biological magnification” How does it affect organisms belonging to different trophic levels particularly the tertiary consumers?
11.  What happens when higher energy ultraviolet radiations act on the oxygen at the higher level of the atmosphere?
12.  In the given food chain if the amount of energy at the fourth trophic level is 4 kJ, what will be the energy available at the producer level? Grass → Grasshopper → Frog → Snake

13. Which of the following chemicals causes depletion of the ozone layer?

a. Carbon tetrachloride

b. Methane

c. Chlorofluorocarbon

d. Carbon monoxide

14. In the following food chain, plants provide 500J of energy to rats. How much energy will be available to hawks from snakes? Plants ———> Rats ———> Snakes ———> Hawks
15. Why are bacteria and fungi called decomposers? List any two advantages of decomposers to the environment.

Thus, we hope that our detailed Class 10 Our Environment notes help you understand the essentials of this chapter. Planning to opt for Science after 10th? Reach out to our Leverage Edu experts and we will guide you in making an informed decision regarding the selection of the right stream after class 10th! Sign up for a free session with us today!