Introduction to Our Environment
The word “environment” is derived from the French word “environ”, which means surrounding. Therefore, the word environment can be defined as our surroundings or the conditions in which all living organisms live. Our environment is made up of both living and non-living components and other physical and chemical factors that overall determine the well-being of all living beings. In this class 10 science chapter 15, our environment notes, we discuss the various components of our environment, our interactions with these components, and the effect of our activities on our environment.
Components of Environment
The components are of two types:
- Biotic components: it involves all the living organisms surrounding us. E.g., plants, animals, etc.
- Abiotic components: These involve all the non-living objects surrounding an organism. E.g., soil, sunlight, water, air, etc.
Interactions are always taking place between the biotic components as well as between living organisms and the abiotic components. These interactions lead to an input of energy into our surroundings which is crucial for the sustainability of our environment. Therefore, in a given area, the living organisms and the non-living components form a functional unit, termed an Ecosystem. Therefore, the ecosystem is defined as the interaction between biotic and abiotic components within a given area.
Within an ecosystem, there is a constant flow of energy maintained by food chains, whereby several food chains interlink to form a food web.
Food chain: The transfer of energy and nutrition from their ultimate source in plants through a series of organisms, in which the larger organism always feeds upon the smaller organism, is called the food chain.
Grass →Deer →Tiger
Food web: A network of food chains overlapping in a community is called a food web.
Example: Grass is eaten by a rat, and a rat is eaten by a snake. However, both the rat and the snake is a prey of the eagle.
The food chain or the food web can be classified into various levels based on the flow of energy from one organism to the next. These are as follows:
The producers: All green plants and certain bacteria, and blue-green algae fall under this level. These organisms can produce their food through a process called photosynthesis. hereby, they are termed producers or autotrophs.
The organisms that consume the producers are called the consumers and are of the following types:
- Herbivore (primary consumer): The organisms that are directly dependent on or feed upon the producers are called herbivores. E.g., cow, deer, rabbit, horse, etc.
- Carnivores (secondary consumer): The organisms that feed upon herbivores are called carnivores. Among the carnivores are animals that make up the top level of predators who are usually not killed and fed upon by other organisms, e.g., tiger, lion, wolf, eagle, etc., and form the secondary consumers.
- Omnivores: Those animals that can live on both plant and animal sources of food are called omnivores. E.g., humans, crows, bears, etc.
- Decomposers: These refer to the microorganisms (bacteria, fungi) that help in the breakdown of dead and decaying organic matter. Decomposers help to transform complex matters into simpler ones, and these substances are later taken up by the plants again.
Mode of Nutrition in Plants and Animals
The two major modes of nutrition securement in the living world are: Autotrophic and Heterotrophic. Autotrophic nutrition refers to the mode of nutrition whereby an organism can make its food matter (e.g., plants and certain bacteria). On the contrary, heterotrophic nutrition refers to the mode of nutrition in which organisms are dependent on plants or other animals for their food (e.g., animals, fungi, etc.)
The Food Pyramid
To properly understand the energy flow within a food chain or web in a community, scientists have developed graphical representations, depicted the shape of a pyramid, and hence called the food pyramid. These pyramids usually start with the producers and are of the following types:
- Pyramid of numbers: This pyramid shows the number of organisms per unit area at various trophic levels of a food chain. This can be either inverted or upright.
- Pyramid of biomass: The graphical representation of the biomass presents at each trophic level.
- Pyramid of energy: Graphical representation that shows the energy flow from one trophic level to the next. This pyramid is always in an upright position with the producers forming the base of the pyramid.
Interdependence Between Organisms
As stated earlier, living organisms interact with each other in an environment. However, there are some cases whereby living organisms live together for shelter and nutrition. This type of relationship can be broadly classified into the following categories:
- Symbiotic relationship: The type of relationship in which both organisms are benefitted from living together. For example, lichens show the association between an alga and a fungus. The algae provide food to the fungus whereby the fungus offers shelter.
- Parasitism: The type of relationship in which one organism is benefitted at the cost of the other. The parasite lives inside the body of another organism called the host and receives nutrition from it.
Law of Conservation of Energy
This law states that energy can neither be created nor destroyed; it only changes from one form to the other. In the biological context, energy gets transferred from one organism to the other across various trophic levels based on eating and being eaten.
With the rise in population, the interaction between living organisms and the abiotic components has increased subsequently leading to pollution. Pollution refers to the process of entry of harmful substances into our surroundings due to both natural and man-made causes.
With the rise in the number of individuals at each trophic level, there has been a disbalance in the number of prey and predators. Humans have increased the usage of pesticides such as DDT to meet the high demands of food. This, in turn, has led to an accumulation of these pesticides in the body of top-level predators, a phenomenon called biological magnification. The plants take up these pesticides along with water, which is later passed on to the other organisms, leading to several health adversaries.
Depletion of the ozone layer
Three oxygen atoms combine to produce the molecule of ozone (O3). While all aerobic forms of life require O2 or oxygen as we often refer to it. Ozone is a poison that can kill. However, ozone serves a crucial purpose at greater atmospheric altitudes. It protects the earth’s surface from the Sun’s ultraviolet (UV) radiation. It is extremely harmful to living things; for instance, it is known to give humans skin cancer.
Ozone is a byproduct of UV light acting on oxygen (O2) molecules at higher altitudes in the atmosphere. Some molecules of oxygen (O2) are broken apart into free oxygen (O) atoms by the higher energy UV rays. Ozone is created by these atoms joining with molecules of oxygen as shown:
The 1980s saw a substantial decline in the amount of ozone in the atmosphere. Synthetic chemicals like chlorofluorocarbons (CFCs), which are used in fire extinguishers and as refrigerants, have been connected to this decline. The United Nations Environment Program (UNEP) was successful in negotiating a deal in 1987 to maintain the 1986 level of CFC production. All manufacturing firms are now required to produce CFC-free refrigerators on a global scale.
Solid waste management
The increase in the world’s population has also led to the accumulation of solid wastes that are becoming tougher to control and manage with every passing day. Wastes such as bottles, caps, plastics, etc. are getting dumped at dumpsters or ending up in our ocean, thereby polluting our surroundings.
Biodegradable refers to substances that can be broken down by biological processes. How many of the materials you buried degraded naturally? A substance is considered non-biodegradable if it cannot degrade in this way. These compounds may be harmful to different ecosystem components, or they may just be inert and last a very long time in the environment.
Ways to reduce pollution
- Segregation and separation of waste.
- Following the 3Rs, i.e., reduce, reuse, and recycle.
- Change in our lifestyle and opting for a more sustainable method of living.
- Opting for clean sources of energy.
We hope these “our environment class 10 CBSE notes” help you pass your exams. All the best!