Our Environment | Olympiad Preparation for Class 10 PDF Download

Introduction

The environment is the sum total of everything around an organism including both living and nonliving components. The living and nonliving factors influence the environment.

Components of environment

1. Abiotic: They are the nonliving factors that affect the environment. They include the following:

• Climatic factors like wind, water, light  and temperature.
• Physiographic factors like height, slope.
• Edaphic factors like minerals, soil, texture, soil organism, ph of the soil, etc.

2. Biotic: These are the living factors that affect the environment. They include the following-

• Grazing animals
• Insects
• Lichens
• Humans
• Parasites

Waste

We come across many waste things around us like garbage, kitchen waste, etc. They are simply defined as useless or discarded materials. They may be gaseous, liquid or solid in nature. Their disposal is a big problem and on the basis of degradation, they are classified in the following ways:

• Biodegradable waste: It is the waste that is broken down by biological processes, like by the saprophytes. For example kitchen waste, sewage, cotton, cloth, etc.
• Non biodegradable waste: These are those wastes which can not be broken down by the biological processes. For example plastics, polythene bags, etc. This non-biodegradable waste creates environmental pollution.

Environmental Pollution

As you have seen many times that the resources around us are not clean and pure enough like air is not free of harmful gases, smoke, etc, water does not seem to be clear and transparent. They are actually polluted and have certain substances that make them look like they are polluted. Thus, we can define pollution as an undesirable change in the physical, chemical, and biological characteristics of air, water, and soil. This pollution has lead to several health-related problems like asthma, bronchitis, ecological imbalance, etc.

Ecosystem

It is a structural and functional unit of the biosphere comprising of living organisms and their interaction with food chain and biogeochemical cycles. For example a garden has many different plants in it such as grasses, trees, flowering and non flowering plants, animals like frogs, insects, etc. These organisms interact with each other and they are also affected by abiotic factors that affect their growth, reproduction and other activities.
There are two types of ecosystem :

• Natural Ecosystem like the lakes, ponds, forests, etc.
• Artificial Ecosystem like the garden, crop field, aquarium, etc.

There are many organisms in the ecosystem which are categorized into different groups:

• Producers: The organisms that can make their food by themselves by utilising solar energy like very small aquatic green plants called phytoplanktons.
• Consumers: The organisms that depend upon producers for their nutritional requirement. They can be herbivores, carnivores and omnivores.
• Herbivores: They are those that feed on green plants for their food. They are also called primary consumers.
• Carnivores: The animals which depend on animals for their food requirement.
• Omnivores: They are those animals that feed on plants. as well as on animals.
• Parasites: They are those that live on other organisms body (host) either on or inside the food and fulfill its nutritional requirement.
• Decomposers: They are those organisms that feed on dead and decaying organic matter.  Example: Microorganisms, etc.

Food Chain

It is the process of eating and being eaten or we can say that in this sequence, one organism eats another organism and the same is eaten by some other organism.
A food chain generally consists of producers, consumers and decomposers. Each step of the food chain is called its trophic level at which transfer of energy takes place. Usually a food chain consists of 4-5 trophic levels because after that energy availability is almost nil. The food chains are represented by drawing pyramids where different levels are occupied by different organisms as shown:

Examples of food chains:
Terrestrial Food Chain

• Green Plants → Deer → Lion
• Grass → Grasshopper → Frog → Snake → Hawk
  For example:  Aquatic Food Chain
• Aquatic Plants → Zooplankton → Small Fish → Large Fish

Food web

It is defined as an interconnected food chain. In this, any organism is eaten by several other organisms.

Energy transfer in the food chain

According to it, the energy that gets transferred at each trophic level in a food chain is only ten percent of the energy that was available at the previous level. It is described as follows:
The green plants capture 1% of the energy of sunlight that falls on them and convert it into chemical energy of food. When primary consumers eat the green plants, a major part of energy is lost in the environment as community heat and only 10% of the energy available is transferred to another level. So this is the law that only 10% of total energy is transferred from one Trophic level to another.

Biological Magnification

It is defined as an increase in the concentration of some harmful substances at trophic levels. Sometimes some harmful chemicals may enter into the food chain. It is surprising to note that at each step, the concentration of it does not decrease like energy, rather it keeps on increasing at each level and the maximum sufferer is the last organism. Like in the given figure, the maximum sufferer is the lion.

Ozone Depletion

Ozone: It is a molecule of three oxygen atoms i.e. O₃. It is present in the stratosphere, a layer of the atmosphere. Ozone Is formed when u-v rays in upper atmosphere split oxygen atoms that is-
When oxygen molecule splits into atoms, then each atom combines with an undissociated molecule of oxygen to form ozone. Ozone protects us from the ultra violet radiations as it doesn’t allow them to enter the earth’s atmosphere.
if they enter the earth’s atmosphere, they may harm us in many ways such as:

• They may raise the temperature of earth
• They can cause global warming
• They may cause skin disorders
• It can cause eye disorders and many more.
  

The thinning of the ozone layer by air pollutants is called ozone depletion. For this, some synthetic chemicals are responsible like Chloro Fluoro Carbons that are used in refrigerators, air conditioners, etc.

Montreal Protocol

It is an agreement made by industrialized nations to freeze the production of CFCs and make use of some alternative source. It was done in 1987 UNEP (United Nations Environment Program). Now, instead of using CFCs, HFCS and PFCs are used that are somehow helping in saving the ozone layer.

Management of garbage

Garbage: It is refuse of fruits, vegetables and food along with other domestic waste. As these are considered as waste, there are certain methods for disposing the waste in the right way.
These are as follows:

• Landfills
• Preparation of compost
• Burning at high temperature (incineration).
• Production of biogas and manures