Our Environment Class 10 Notes CBSE Science Chapter 15 (Free PDF Download)

1. What Happens to the Environment When We Add Waste to it?

The environment of an organism refers to the physical and biological conditions in which the organism lives. The physical conditions consist of various factors like soil, temperature, light,  etc. Whereas the biological conditions include the plants, animals, and microorganisms around it. A slight change in any of these conditions can affect the organism.

When the waste generated is added to the environment it disturbs the ecological balance.  The wastes are broadly classified into two categories:-

Substances that can be broken down by biological processes are known as biodegradable. On the other hand, substances that can not be broken down by biological processes are known as non-biodegradable. These substances can be inert and remain in the environment for a very long time causing harm to the various members of the ecosystem.

2. What are the Components of the Ecosystem?

All organisms including plants, animals, microorganisms, and human beings interact with the physical surroundings as well as with each other to maintain balance in our environment.

An ecosystem is a community of organisms with their physical environment interacting with each other as an ecological unit, leading to the flow of energy. An ecosystem is made up of biotic components which include living organisms and abiotic components which include physical factors like temperature, rainfall, wind, soil, and minerals.

An ecosystem can be of two types:

Natural :  Ponds, forests, and lakes are natural ecosystems 

Artificial:  garden and crop fields are man-made 

In both of the above ecosystems, all living organisms interact with each other and their growth, reproduction, and some of the other activities are affected by the abiotic components of the ecosystem.

Organisms present in the ecosystem can be further categorized into producers, consumers, and decomposers in accordance with the manner in which they obtain their nutrition from the environment. 

Producers are organisms that are capable of producing their own food without the help of any other organism. They are also called autotrophs. They synthesize their food from inorganic substances by a process called photosynthesis. Autotrophs are the green plants, phytoplankton, and blue-green algae.

Consumers are the organisms that do not produce food but depend directly or indirectly on producers for their food needs. These are called heterotrophs. Consumers can be further classified into herbivores, carnivores, omnivores, and parasites. For example Humans, snakes. Decomposers are the organisms that feed on dead and decaying matter and break down the complex organic substances into the simple inorganic substances. These simpler substances go into the soil and are used up again by the plants. Eg: Bacteria and fungi.

2.1 Food Chains and Webs:

The series of organisms that are taking part at various biotic levels constitute a food chain. Food chains signify the feeding relationship between the organisms in an ecosystem. In the food chain, the flow of energy from one species to another occurs. Every food chain always begins with producers.

The successive levels present in the food chains of a community are known as trophic levels. From autotrophs, the energy is passed to the heterotrophs and decomposers. When this energy is transferred from one level to the other level, some of the energy is lost to the environment in forms that cannot be used again.  A common example of food chains are:-

Plants → Deer →  Lion

The food chain consists of up to three or four trophic levels. Since the loss of energy at every step is so huge that a very small amount of usable energy remains when it reaches the fourth trophic level. The number of individuals at the lower trophic levels of an ecosystem is generally more therefore the largest number is of the producers.

The length and complexity of food chains differ. Every organism is in general eaten by two or more other kinds of organisms which in turn are eaten by several other organisms belonging to a higher level. This relationship between organisms can be shown by a series of branching lines known as the food web. Many cross-linked food chains constitute the food web.

The flow of energy between the trophic levels in any ecosystem is unidirectional. The energy that is captured by the autotrophs is passed to the higher trophic levels and energy does not revert back to the lower level. Some of the harmful chemicals enter our bodies through the food chain. For example use of several pesticides and other chemicals to protect the crops from diseases and pests runoff with water in the field which are taken up by the fishes entering in the food chain. 

Biological magnification is a phenomenon by which harmful substances or chemicals accumulate from the lower trophic level to a higher one. As human beings are at the top level in any food chain, the maximum concentration of these harmful chemicals gets accumulated in the body which can cause death of the person.

3. How Does the Environment Affect Our Activities?

3.1 Ozone Layer and its Depletion.

Ozone molecule consists of three oxygen atoms. The ozone layer is present in the upper layer of the atmosphere i.e. stratosphere. It is a very deadly poison. It is responsible for causing skin cancer in human beings. Whereas, at the higher levels of the atmosphere, it protects us from harmful UV radiations of the sun which is dangerous to living organisms. Ozone depletion is the marked reduction of ozone molecules in the stratosphere due to chlorofluorocarbons (CFCs) used in refrigerants and other coolants. Oxygen in the presence of ultraviolet rays gets broken down to nascent oxygen molecules. This nascent oxygen further reacts with the oxygen present in the atmosphere and forms ozone molecules. 

In order to limit the damage to the ozone layer the release of CFC s into the atmosphere needs to be reduced instead alternatives should be used.

3.2 Managing the Garbage Produced:

Improvements in the lifestyle have to lead to greater amounts of waste material generation. Changes in the packaging of items have resulted in huge amounts of waste becoming non-biodegradable. Increased use of non-biodegradable items has left the environment polluted with them. In order to manage this waste we can do following:-

1. Use of concept of 3R's (reduce, reuse and recycle).

2. Separation of biodegradable and nonbiodegradable waste.

Ch 15 Class 10 Science Notes: Details of Ecosystem

• An ecosystem consists of both biotic and abiotic components of a specific area. E.g. forest ecosystem, lake ecosystem and marine ecosystem as mentioned in Science Chapter 15 Class 10 notes.

• In a specific geographical region, every living organism interconnects with each other. Their reproduction and growth and all other activities are dependent on abiotic components of the ecosystem.

• Green plants can produce food by using photosynthesis, so they are called producers.

• The species depending directly or indirectly on the organisms are called herbivores, carnivores and omnivores.

• Animals that eat plants are called herbivores and they are also known as primary consumers. E.g. cow, goat, deer.

• Animals that eat other animals are called carnivores and are known as secondary consumers. E.g. lion, tiger, snake 

• Animals that eat both are called omnivores.

• The microorganisms like fungi, bacteria break down all dead remains and are called decomposers.

Class 10 Science Chapter 15 Notes: Food Chain

The concept of the food chain is an important part of Ch 15 Science Class 10 notes. A brief overview of it is given below:

• A food chain is formed by a series of animals that feed each other.

• A trophic level is formed by each level.

• Autotrophs appear in the first trophic level.

• Herbivores are present in the second trophic level.

• Small carnivores are present in the third trophic level and the larger ones in the fourth trophic level.

Notes of Chapter 15 Science Class 10: Human Activities Affecting The Environment

According to Class 10th Science Chapter 15 notes, there are various human activities that affect the environment.

Plastic Production

The invention of plastics has created a problematic situation for the earth. Waste plastics are present everywhere on the globe, even in the ocean. The use of plastics leaves a long-lasting consequence on the Earth. The estimated amount of plastics produced annually is 5.2 trillion. The plastics that are present in the water destroy the ecosystem and change the reproductive pattern of the animals. 

Emission of Carbon Dioxide and Greenhouse Gases

Emission of carbon dioxide and greenhouse gases are induced by humans through man-made products and combustion of fossil fuel. In order to generate energy, the world’s population has been largely dependent on the carbon-rich fossils such as oil, coal and gas. Nowadays, the level of carbon dioxide is rising surprisingly than ever. This has caused a rise in the global temperature and the sea level.

Overexploitation and Overhunting

Overexploitation and overhunting of natural resources with activities such as mining and fishing are causing a reduction in plants and animals. The existence of plants and animals has been affected by overexploitation and overhunting. Such activities do not allow replenishment or growth and development. Extinction and destruction are caused by overhunting.

Class 10th Ch 15 Science Notes: Manage the Environment Impact of Your Work

Class 10 Chapter 15 science notes presents students with various ways in which one can reduce his or her dangerous impact on the environment 

• Work activities and usage of resources should be organized so that they are effective and efficient. One also needs to comply with environmental policies and legal requirements.

• Environmental impact of one’s activities should be identified and used responsibly. 

• Risks should be identified and reported that is out of one’s control.

• People should be encouraged so that they contribute their part in improving the environment.

Other Related Links

• Syllabus for CBSE Class 10 Science Term (1 & 2) 2024-25

• CBSE Notes for Class 10 Science

• NCERT Solutions for Class 10

• Sample Papers for Class 10

• NCERT Exemplar for Class 10 Science

• CBSE Class 10 Previous Year Question Paper

• Important Questions for CBSE Class 10 Science

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