1. What is environment?
Ans:In a broad sense, environment denotes the condition around an orgnism or a community of organisms. Such a condition includes all necessary elements for survival. These elements are both biotic and abiotic. The biotic elements include all sorts of plants and animals ranging from microbes to large mammals. On the other hand, land, water, air and all other lifeless elements fall under the abiotic category. These biotic and abiotic elements through their interaction create necessary condition or environment for life. In other words, each and every organism or community of organisms depend upon the conditions around. Thus organisms are also constituents of their environment. Human beings are also an organism and they also depend on the environment around.
2. What are the major spheres of environment?
Ans: The four spheres of environment are -
(A) Lithosphere :
The land component of the earth composed of rocks, soils, minerals, etc forms the lithosphere. The lithosphere covers all the continents where we find the mountains, hills, plateaus, plains, valleys and coasts. The characteristics of the lithosphere and its change in course of time depends on the other three components (hydrosphere, atmosphere and biosphere) of the earth's environmental system.
(B) Hydrosphere :
The seas and oceans have formed the earth's hydrosphere. The hydrosphere covers about 71% of the earth's surface. The rivers, lakes and other waterbodies distributed in the continents are also parts of the hydrosphere. The status and change in the hydrosphere depend on the status of the lithosphere, atmosphere and biosphere.
(C) Atmosphere:
From the earth's surface upward extends a gaseous layer. Composed of Oxygen, Nitrogen, Hydrogen, Carbon-di-Oxide, Argon, etc. this gaseous layer is called the atmosphere. The atmosphere extends broadly to a height of about 10000 km from the surface of the earth. The characteristics and change of the atmosphere depend on the other three components of the environmental system.
(D)Biosphere :
The biosphere covers those parts of the earth's environment where life forms occur. These include the earth's surface, down to a few meters from the earth's surface, the seas and oceans and the lower. ştratum of the atmosphere where birds and insects fly. So far 1.75 million species of plants and animals have been identified in the biosphere. Of these, human beings (Homo sapiens) constitute only a single species.
3) What are the factors responsible for the rapid change of the earth's environment?
Ans: a) population growth
b) industrialisation
c) urbanisation
d) expansion of transport and communication.
4) Fill in the blank.
In the atmosphere the Carbon -di- Oxide content 0.035%.
5) What are the major environmental problems?
Ans: a) pollution
b) desertification
c) global warming
6) What is global warming? What are its causes?
Ans:Global warming is a gradual increase in the earth’s temperature generally due to the greenhouse effect caused by increased levels of carbon dioxide, CFCs, and other pollutants.
It is the phenomenon of a gradual increase in the temperature near the earth’s surface.
Causes of global warming:
There are several causes of global warming . They are as follows:
1)Man-made Causes of Global Warming
a)Deforestation
Plants are the main source of oxygen. They take in carbon dioxide and release oxygen thereby maintaining environmental balance. Forests are being depleted for many domestic and commercial purposes. This has led to an environmental imbalance, thereby giving rise to global warming.
b)Use of Vehicles
The use of vehicles, even for a very short distance results in various gaseous emissions. Vehicles burn fossil fuels which emit a large amount of carbon dioxide and other toxins into the atmosphere resulting in a temperature increase.
c)Chlorofluorocarbon
With the excessive use of air conditioners and refrigerators, humans have been adding CFCs into the environment which affects the atmospheric ozone layer. The ozone layer protects the earth surface from the harmful ultraviolet rays emitted by the sun. The CFCs have led to ozone layer depletion making way for the ultraviolet rays, thereby increasing the temperature of the earth.
d)Industrial Development
With the advent of industrialization, the temperature of the earth has been increasing rapidly. The harmful emissions from the factories add to the increasing temperature of the earth.
e)Agriculture
Various farming activities produce carbon dioxide and methane gas. These add to the greenhouse gases in the atmosphere and increase the temperature of the earth.
f)High population
An increase in population means more people breathing. This leads to an increase in the level of carbon dioxide, the primary gas causing global warming, in the atmosphere.
2)Natural Causes of Global Warming
a)Volcanoes
Volcanoes are one of the largest natural contributors to global warming. The ash and smoke emitted during volcanic eruptions goes out into the atmosphere and affects the climate.
b)Water Vapour
Water vapour is a kind of greenhouse gas. Due to the increase in the earth’s temperature, more water gets evaporated from the water bodies and stays in the atmosphere adding to global warming.
c)Melting Permafrost
Permafrost is frozen soil that has environmental gases trapped in it for several years and is present below Earth’s surface. It is present in glaciers. As the permafrost melts, it releases the gases back into the atmosphere, increasing Earth’s temperature.
d)Forest Fire
forest fires emit a large amount of carbon-containing smoke. These gases are released into the atmosphere and increase the earth’s temperature resulting in global warming.
7)What are the major effects of Global Warming?
Ans: Major effects of global warming are:
a)Increase in Temperature
Global warming has led to an incredible increase in earth’s temperature.
b)Threats to the Ecosystem
Global warming has affected the coral reefs that can lead to the loss of plant and animal lives. Increase in global temperatures has made the fragility of coral reefs even worse.
c)Climate Change
Global warming has led to a change in climatic conditions. There are droughts at some places and floods at some. This climatic imbalance is the result of global warming.
d)Spread of Diseases
Global warming leads to a change in the patterns of heat and humidity. This has led to the movement of mosquitoes that carry and spread diseases.
e)High Mortality Rates
Due to an increase in floods, tsunamis and other natural calamities, the average death toll usually increases. Also, such events can bring about the spread of diseases that can hamper human life.
f)Loss of Natural Habitat
A global shift in the climate leads to the loss of habitats of several plants and animals. In this case, the animals need to migrate from their natural habitat and many of them even become extinct. This is yet another major impact of global warming on biodiversity.
8) What is desertification?
Ans: Desertification is a process with endorse the productive areas of the tropical region a desert- like situation. Desertification denotes the spread of the deserts to their peripheral areas.
According to a convention on desertification, the meeting defined Desertification as-" the diminution or destruction of the biological potential of the land leading ultimately to desert- like conditions ".
At present, around 35% of the world's land surface is affected by the process of Desertification.
9) Write the affect of desertification?
Ans: Desertification affects the land productivity and the growth of natural vegetation.
10) What do you mean by pollution?
Ans: The process of contamination of the environment by harmful substances is called pollution.
11) What is land pollution? What are its causes?
Ans: Land looses its natural properties and fertility ,when it comes into contact with certain chemicals ,poisonous metals, industrial wastas, radioactive substances, acid rain and so on. In such a situation , land is considered to be polluted.
Its causes:
a) modern farming practice
b) expanding industries
c) increasing deforestation
12) What is air pollution?
Ans: The atmosphere is mainly composed of gaseous. substances. Some liquid and solid substances are also present in the atmosphere in different states. Among the gaseous substances, Nitrogen (78.08%), Oxygen (20.94%), Argon (0.93%) and Carbon di-Oxide (0.035%) are important. By maintaining a definite proportion, these substances keep the atmosphere in a balance. Surely various problems will occur, if this balance is somehow disturbed. The natural state of the atmosphere may be changed, if certain solid, liquid or gaseous substances are added to the atmosphere by some natural or human processes. If such a change causes some harm to the biotic and abiotic elements, then the atmosphere is said to be polluted.
13) What are the causes of air pollution?
Ans:
a) Volcanic eruption: The smoke,ashes and gases that come out from the earth's interior during eruption pollute the air.
b) growth of industries
c) urbanisation
d) growth of vehicular traffic
e) nuclear explosions.
14) What is the consequence of air pollution.
Ans:
a)Occurance of acid rain: Generally acid rain occurs when there is maximum concentration of Sulphur di -oxide and Nitrogen dioxide in the atmosphere.
15)What is water pollution?
Ans: The natural state or quality of water gets changed when certain chemical substances, particles ,microbes, radiations are added to or pass through it. The process of such change in water is called water pollution.
Causes of water pollution:
1) the industrial wastes
2) the urban wastes.
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