10th Class Science Our Environment

Our Environment

The environment is the physical surrounding around us that includes biotic and abiotic components such as plants, animals, human beings, microorganisms, water, soil, air, etc. These all are interdependent and cannot survive without each other. Human being is the only organism who can cause imbalance in natural environment because of their greed. A balanced environment is necessary for the proper growth of all forms of life.

Ecosystem and Its Components

An ecosystem consists of all the biotic factors such as plants, animals and microorganisms and abiotic factors such as soil, air and water, etc. In an area, these all factors function together. The following are the examples of ecosystems:

• Pond
• Forest
• Estuary
• Grassland

Ecosystem can be studied through the study of certain processes that link the living or biotic components to the non-living or abiotic components. The two main processes that comprise the field of ecosystem ecology are energy transformations and biogeochemical circle. Study of individuals in an ecosystem comprise of the study of physiology, reproduction, development and behavior. The study of species comprises of their habitat and resource needs, their group behaviors, population growth and what limits their abundance or causes extinction. The study of communities comprises of how populations of many species interact with one another, such as predators and their prey or competitors that share common needs or resources.

Components of an Ecosystem

The ecosystem comprises of biotic and abiotic components. The following table shows the biotic and abiotic components:

Food chains and food Web

In an ecosystem, there are different types of animals and plants. These all plants and animals are directly or indirectly depend on each other for their food. A food chain shows how each living thing obtains their food. A food chain consists of producers and consumers. Plants are the producers whereas herbivorous, carnivorous and omnivorous animals are consumers. For example, plants are eaten by herbivorous animals and herbivorous animals are eaten by carnivorous animals. A food chain always starts with plant life and ends with an animal.

Important points about a food chain

• Plants are called producers because they make their own food in the presence of sunlight, carbon dioxide and water.
• Animals cannot make their own food. They eat plants and/or other animals. They are called consumers. There are three groups of consumers.
• Animals that eat only plants are called herbivorous (or primary consumers).
• Animals that eat only other animals are called carnivorous.
• Carnivorous that eat herbivorous are called secondary consumers.
• Carnivorous that eat other carnivorous are called tertiary consumers e.g., hawk.
• Animals and humans who eat both animals and plants are called omnivorous.
• There are decomposers such as bacteria and fungi which feed on decaying matter.
• The decaying process is increased because of the decomposers. They release mineral salts that are absorbed by plants as nutrients.

In a food chain, a lot of energy is wasted while transformation of energy from one category to another. For example, when herbivorous eats plants, only a fraction of available energy is transferred in the body of herbivorous animals and major part of it is lost. When a herbivorous is eaten by a carnivorous, a very small amount of energy is passed into the body of carnivorous animals and rest of the energy is wasted. Thus, in a food chain, the transfer of energy decreases from producer level to consumer level. The large amount of energy is lost at each level and thus, in the amount of energy that is transferred gets lesser and lesser.

The following figure shows the supply of energy at each trophic level:

Generally there are four or five trophic levels in a food chain because the energy level reduces to zero at the end of the food chain. The organisms do not get enough energy to stay alive after a certain level. Many organisms are involved in more than one food chain to fulfil their energy requirements. There are many food chains. These food chains are interconnected. The interconnected food chains make a food web.

The following figure shows a food web:

The existence of each organism at various levels is necessary to maintain the balance in ecosystem. Any change in the size of population in a food chain will directly affect the population of other organism.

It is the interdependence of animals and plants in a food chain that helps them to maintain the balance of population of each species within a community. For example, if the number of herbivorous animals will increase then the number of plants will decrease automatically. Finally this will lead to starvation among herbivorous animals. If the condition gets reversed then number of plants will increase and the number of carnivorous animals will decrease as they will not get sufficient food. This will create imbalance in an ecosystem.

Human Activities and their Impacts on the Environment

Human beings are the finest creation of the nature. They have the most advance brain that makes them superior from other animals. But, unfortunately it is the human being who has been destroying the nature day by day. Their activities have been causing enough harm to the ecological system. Depletion of ozone layer is one of the most unfortunate things that has happened because of the human activities.

Depletion of ozone layer

The ozone layer protects the earth from the harmful ultraviolet rays of the sun. The depletion in ozone layer will endanger the life on the earth. It will not only affect the humans but also all the living things. The ozone layer is found on the outer surface of the atmosphere that is about

30 miles above the earth. The harmful ultra violet rays are stopped by this layer in the outer surface. These rays thus cannot reach on the surface of the earth and cannot cause any harm to life on it.

Causes of depletion

There are many factors that are responsible for the depletion of ozone layer. One of the leading causes for the depletion is the production and emission of chlorofluorocarbons (CFCS). CFCs have a great industrial value and are used in many products. It is used in refrigerators, home insulation, plastic foam and throwaway food containers.

Effects of Depletion of Ozone Layer

The effects of depletion of ozone layer are disastrous. Even a slight depletion can cause huge loss. The depletion will allow more ultra violet rays to enter the earth. Ultra violet rays cause skin cancer which is fatal. The depletion can cause many other diseases. A large population of the earth will not be able to survive.

The environment will also be negatively affected by ozone depletion. It not only disrupt the good chain but also the life cycles of plants. Effects on animals will also be severe and are very difficult to foresee.

Oceans will be hit hard as well. Many microbes that are found in the sea will not be able to survive. Destruction of microbes will lead to the destruction of other forms of life as well. There are many other ill effects of depletion. They are the following:

• Destruction of forests
• Affect on climate
• Change in wind patterns
• Overall climate change