source of energy
class x
Question 1:
What is a good source of energy?
Answer 1:
A good source
of energy should have
the
following qualities:
Ø
It should be easily available.
Ø It should do a large
amount of work (or produce
large amount of heat) per unit volume/mass.
Ø
It should be easy to
store and transport.
Ø
It should be economical.
Ø
It should cause less environmental pollution.
Question 2:
What is a good fuel?
Answer 2:
A good fuel produces
a large amount of heat on burning, does not produce a lot of
smoke and is easily
available.
Question 3:
If you could use any source of energy for heating
your food, which one would you use and why?
Answer 3:
We shall use LPG/CNG gas or electricity for heating
our food because these are efficient
ways of supplying energy. Thermal efficiency of the energy
source is large,
there is less pollution
and the source
can be used easily.
Question 1:
What are the disadvantages of fossil fuels?
Answer 1:
There are following
disadvantages of
fossil fuels like coal and petroleum:
Ø
Burning of coal or petroleum causes air pollution.
Ø Acidic oxides like oxides of carbon, nitrogen
and sulphur are released
on burning fossil fuels.
These oxides lead to acid rains, which affect our water and soil resources.
Ø
Carbon dioxide gas also
causes greenhouse effect in
atmosphere.
Ø
Fossil fuels are non-renewable sources of energy.
Question 2:
Why are we looking
at alternate sources of energy?
Answer 2:
Fossil fuels, which have been traditionally used by human beings as an energy
sources, are non-renewable sources of energy.
These sources of energy are limited
and cannot replenish on their own. They are being consumed at a large rate. If this rate of consumption continues, then the fossil fuels would be exhausted
from the Earth.
Therefore, we should look for alternate sources of energy.
Question 3:
How has the traditional use of wind and water energy been modified for our convenience?
Answer 3:
To use energy of flowing
water large dams are built in hilly regions
to store huge amount of water at a height. The stored water from high level in dam is carried
through pipes to the turbine at the bottom
of the dam and runs hydropower plant. Similarly, the wind energy is used to generate electricity. For the same purpose, the rotatory
motion of windmill
is used to tum the turbine
of the electric
generator.
Question 1:
What kind of mirror – concave, convex or plain – would be best suited for use in
a solar cooker? Why?
Answer 1:
A solar cooker
uses heat of the sunlight
to cook the food. A concave mirror is used in order to reflect and focus sunlight at a particular area. The mirror
focuses all the incident
sunlight at a point. The temperature at that point increases, thereby cooking and heating the
food
placed at that particular
area.
Question 2:
What are the limitations of the energy that can be
obtained from the oceans?
Answer 2:
Energy from the oceans
can be obtained
in the form of tidal energy, wave energy and ocean thermal energy. But these energy
sources suffer from the following
limitations:
Ø
There are very few locations where dams to utilise
tidal energy can be built.
Ø Cost of installation of power houses is extremely high and efficiency of plants is comparatively small.
Ø Power plants built in oceans or at sea-shores will need high continuous maintenance as chances of
corrosion are extremely high.
Question 3:
What is geothermal energy?
Answer 3:
Geothermal energy is the heat energy present inside earth in certain regions called
hot spots. Due to geological changes, molten rocks formed in the deeper hot
regions of earth’s crust are pushed upwards and are trapped in hot spots. When
underground water comes in contact with the hot spot, steam is generated. This
steam is routed through a pipe to a turbine
and used to
generate electricity.
Question 4:
What are the advantages of nuclear energy?
Answer 4:
The advantages of nuclear energy
are as follows:
Ø
Large amount of energy is produced per unit mass.
Ø
It does not produce smoke. It is a clean energy.
Ø Fission of one atom of uranium produces 10 million times the energy
released by burning
of one atom of carbon.
Ø
Fusion of four hydrogen
atoms produces huge amount of energy.
Question 1:
Can any source of energy be pollution-free? Why or why not?
Answer 1:
No source of energy can be pollution-free. It is considered that solar cells are pollution-free. However, even their making causes environmental damage indirectly. Also, in the case of nuclear energy, there is no waste produced after the fusion reactions. However, it is not totally
pollution-free. To start the fusion
reactions, approximately 107 K temperature is required, which is provided
by fission reactions. The wastes released from fission reactions are very
hazardous. Hence, no source of energy is pollution-free.
Question 2:
Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
Answer 2:
Hydrogen can be considered a cleaner
fuel because its burning
produces water vapour which is non-polluting. However, due to explosive nature of hydrogen,
its storage and
transportation is difficult
Question 1:
Name two energy sources
that you would consider to be renewable. Give reasons for your
choices.
Answer 1:
Solar energy, wind energy, ocean energy etc., are renewable
sources of energy
due to the following
reasons:
Ø These forms of energy are available in plenty in our natural environment in the form
of continuous currents of energy.
Ø These energy sources will not be depleted because their supply is large and extraction of usable energy from these sources is negligible.
Question 2:
Give the names of two energy sources that you would consider to be exhaustible. Give reasons
for your choices.
Answer 2:
Coal and petroleum are two exhaustible sources of energy.
These fuels were formed over millions
of years ago and there are only limited
reserves. If we continue
to use them as at present, these
reserves will be exhausted very soon.
Question 1:
What is a good source of energy?
Answer 1:
A good source
of energy should have
the
following qualities:
Ø
It should be easily available.
Ø It should do a large
amount of work (or produce
large amount of heat) per unit volume/mass.
Ø
It should be easy to
store and transport.
Ø
It should be economical.
Ø
It should cause less environmental pollution.
Question 2:
What is a good fuel?
Answer 2:
A good fuel produces
a large amount of heat on burning, does not produce a lot of
smoke and is easily
available.
Question 3:
If you could use any source of energy for heating
your food, which one would you use and why?
Answer 3:
We shall use LPG/CNG gas or electricity for heating
our food because these are efficient
ways of supplying energy. Thermal efficiency of the energy
source is large,
there is less pollution
and the source
can be used easily.
Question 1:
Why are some
substances biodegradable and some non-biodegradable?
Answer 1:
Some substances which are degraded and broken down into simpler substances by the microorganisms, are called biodegradable substances.
For example:
Cotton, wood, paper, wool, etc.
Substance (mainly man-made) that do not degraded or broken down into simpler substances by the action of enzymes secreted by microorganisms are called non- biodegradable substances.
For example:
Plastic, polythene,
DDT, etc.
Question 2:
Give any two
ways in which
biodegradable substances would
affect the environment.
Answer 2:
Ø During decomposition process of biodegradable substances foul smell and some harmful gases are released which make problem for the nearby living
person.
Ø During decomposition it provide a breeding ground for mosquitoes, insects and microbes responsible
for diseases like cholera, diarrhoea, etc.
Question 3:
Give any two ways in which non-biodegradable substances would affect the environment.
Answer 3:
Ø Chemicals like BHC and DDT induce carcinoma (muscle cancer) and growth of tumours.
Ø Handling of waste materials may cause
skin, respiratory and intestinal
infections.
Ø Non-biodegradable substances do not decompose easily so it produces
land and water pollution.
our environment
Question 4:
What will happen if we kill
all the organisms
in one trophic level?
Answer 4:
If we kill all the organisms in one trophic
level, the transfer of
food energy to the next trophic level will stop.
This will cause a break
in the food chain resulting in ecosystem imbalance. As a result, the organisms
of the higher trophic
level will also die, while the individuals of the lower trophic level will exhibit
enormous growth
in their population. Both the conditions will
result in ecological upset.
Question 5:
Will the impact of removing
all the organisms in a trophic level be different
for different trophic levels? Can the organisms
of any trophic level be removed
without causing any damage to the ecosystem?
Answer 5:
Yes, the impact of removing all organisms in a trophic
level will be different for different trophic levels. If all the producers
are killed, it will cause death or migration of the primary
consumers in the ecosystem. In the absence
of producers, subsequent
level of consumers
will also be affected.
But if primary
consumers are removed,
organisms of higher trophic level will die, while those of lower level (producers) show exponential growth much beyond the carrying capacity of the environment. Removal of the organisms in a trophic level will upset the whole ecosystem as all categories of organisms
are linked through
food chain. The survival of organisms
of one trophic
level depends on the existence of the members of other trophic level.
Question 6:
What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
Answer 6:
Progressive increase in the concentration of non-biodegradable substances in a food chain is called
biological magnification. The level of these harmful substances will go on increasing from one trophic level to the next. When certain harmful substances enter the food chain at the level of primary producers,-they get concentrated many times at each
subsequent trophic
level.
Question 7:
What are the problems caused by the non-biodegradable wastes that we generate?
Answer 7:
Non-biodegradable wastes cannot be broken-down into simpler substances. Their volume keeps on increasing creating the problem of their safe disposal. Some of the non-biodegradable wastes like heavy metals and pesticides enter into the food chain and increases in the upper trophic levels. Non-biodegradable wastes reduce the soil fertility
by changing the natural pH balance.
Question 8:
If all the waste we generate
is biodegradable, will this have no impact on the environment?
Answer 8:
Biodegradable wastes are decomposed
by microorganisms into simpler
substances themselves and provide raw materials
for producers, but they also have
adverse effects on the
environment:
Ø Slow decomposition of biodegradable waste will result
in the release of foul smell and harmful gases. When inhaled by human beings,
they may cause irritation, nausea,
giddiness, etc.
Ø Decomposing waste provides breeding ground for some harmful organisms. Abundance of harmful
microorganisms may cause diseases
in animals, plants and human beings.
Ø Increase in the number of microorganisms in aquatic medium will- cause oxygen deficiency in waterbodies.
Question 9:
Why is damage
to the ozone layer a cause for concern?
What steps are being taken to limit this damage?
Answer 9:
Ozone layer is a protective shield around the earth. It prevents
harmful ultraviolet radiation of the sun from reaching
the earth. Air pollutants, like chlorofluorocarbons (CFCs), are causing depletion
of ozone layer. This is allowing greater amount of UV radiation to reach the earth. UV
radiation
upset the ecosystem by affecting
photosynthesis in plants, destroying planktons and decomposers. In human beings, UV radiation may cause skin cancer, cataract of eyes
and damage
to immune system. Several developed as well as developing nations of the world have agreed to sign and obey
the directions of TINEP (United Nations Environment Programme) to freeze the production of CFCs or to 1imit their production to some extent.
Question 1:
What are trophic levels? Give an example of a food chain and state the different trophic
levels in it.
Answer 1:
The various steps in food chain at which transfer of food energy takes place are called trophic
levels.
Example: Food chain operating in a grassland.
Grass → Insects → Frogs → Snakes
1.
Grass → 1st trophic level
2.
Insects → 2nd trophic level
3.
Frogs → 3rd trophic level
4.
Birds → 4th trophic level
Question 2:
What is the role of
decomposers in the
ecosystem?
Answer 2:
Decomposers are microorganisms that act on dead and decaying
bodies of producers and consumers and break them into simple inorganic
compounds. They absorb some of the substances and release the rest into the environment to be recycled
and to be used in future by producers. Thus, decomposers have a key role in the cycling of material
in the biosphere
and provide the raw materials
to the producers. So in this way they
make the soil fertile.
Question 1:
What is ozone and how
does it affect any ecosystem?
Answer 1:
Ozone (O3) is a molecule formed by three atoms of oxygen. Ozone, is a deadly
poison. However, at the higher
levels of the atmosphere, ozone performs an essential
function. It shields
the surface of the earth from ultraviolet (UV) radiation from the Sun.
This radiation is highly damaging to organisms, for example,
it is known to cause skin cancer, cataract and damage the immune system in human beings.
It also destroys
plants and reduces photosynthesis process.
Question 2:
How can you help in reducing the problem of waste disposal?
Give any two methods.
Answer 2:
Ø By minimising
the use of disposal
items and promoting
the use of recycled articles.
Ø Separating biodegradable and non-biodegradable waste before dumping them.
Ø
Recycling the non-biodegradable waste material.
management of natural resources
Question 4:
How can you as an individual contribute or make a difference to the management of (a) forests and wildlife,
(b) water resources
and (c) coal and petroleum?
Answer 4:
(a) Forests and Wildlife
Ø
Take part in community activities with focus on conserving forests and wildlife.
Ø As a tourist follow
all principles of conservation.
Ø Help organisations engaged in conservation of forests and wildlife
(b) Water Resources
Ø Save water
in
domestic use.
Ø Install a system for rainwater harvesting.
(c) Coal and Petroleum
Ø Save electricity whenever
required.
Ø Install electric
gadgets that use
less power.
Ø Use public
transport.
Question 5:
What can you as an individual
do to reduce your consumption of the various
natural resources?
Answer 5:
Ø Save electricity.
Ø
Do not waste food.
Ø Save water.
Ø Use cooking
gas instead of wood for
cooking.
Ø Observe the principle of three R's (Reduce, Recycle
and Reuse).
Question 6:
List five things you have done over
the last one week to –
(a) conserve our
natural resources.
(b) increase the
pressure on our natural resources.
Answer 6:
(a) Five things done
to conserve natural resources are:
Ø Used energy efficient electrical appliances.
Ø
Used only
as much of electricity as was required.
Ø Kept the water tap closed while
brushing the teeth.
Ø Convinced mother to cook the food in a
solar cooker.
Ø Used public transport for school instead of parent's car.
(b) Five things done to increase the pressure on natural
resources:
Ø
Went to school on
a bike instead of
cycle.
Ø Forgot to switch off fan while going out
Ø Wasted food.
Ø Used more paper than required for
printing on computer.
Ø
Wastage of water resource.
Question 7:
On the basis of the issues raised in this chapter, what changes would you incorporate in your life-style in a move towards a sustainable use of our resources?
Answer 7:
Three methods of producing
magnetic field are
as follows:
Ø
Will move in public
transport system to conserve
petrol.
Ø
Instead of coal or natural gas,
will prefer to use
solar energy for cooking.
Ø
Wilt obey
rationalised husbanding of all renewable
resources.
Ø
Take care not to pollute the environment with waste.
Ø
Should realise that we are
living in a community and are not alone.
Question 1:
What changes can you make in your habits to become
more environment- friendly?
Answer 1:
Ø
Stop wastage of water.
Ø
Switching off unnecessary lights and
fans.
Ø
Don't waste food. Take as much as you require.
Ø
Walking down or use cycle for going to nearby
market instead of using vehicle.
Ø Separate wastes
into recyclable and non-recyclable.
Ø
Reuse carry bags, packing materials, plastic containers and other reusable material.
Question 2:
What would be the advantages of exploiting resources with short-term aims?
Answer 2:
The advantage of exploiting
resources with short
term aim is to
meet the immediate
basic human needs.
Question 3:
How would these advantages differ from the advantages
of using a long-term perspective in managing
our resources?
Answer 3:
Short term exploitation of natural resources fulfil the current demand. It is beneficial for the present
generation only, whereas, management of resources
with long term perspective is aimed to fulfil the needs of future
generations. Long term use
of resources can be
achieved through its
sustainable use.
Question 4:
Why do you think there should be equitable distribution of resources? What forces would be working against an equitable
distribution of our resources?
Answer 4:
Equitable distribution of resources will ensure benefits to all the sections
of the society
rich as well as poor. This is necessary
for the growth and development
of a country. Money
force is the main factor which is working against an equitable distribution of resources
as rich people and rich nations try to encroach upon the share
of the
poor people or poor nations.
Question 1:
Why should we conserve forests and wildlife?
Answer 1:
Wildlife and forests
should be conserved
for the following reasons:
Ø
To prevent loss of ecological
stability
Ø
To preserve biodiversity
Ø
To obtain medicine, wood,
fruits, etc., products in
a sustainable manner
Ø
To promote social and economic growth.
Question 2:
Suggest some approaches towards the conservation of forests.
Answer 2:
Ø Forests can be conserved by:
Ø
Preventing the process of deforestation
Ø
Preventing cattle ranching in the
forest
Ø
Promoting afforestation
Ø
Preventing the soil erosion
Ø
Mobilising people's active cooperation
Question 1:
Find out about the traditional systems of water harvesting/management in your region.
Answer 1:
The traditional systems of water harvesting/management in different region are different. The system of water
harvesting in our
region are ponds, pits, lakes and other
reservoirs where rainwater is stored.
Question 2:
Compare the above system with the probable systems in hilly/mountainous areas or plains or
plateau regions.
Answer 2:
In mountainous areas instead of traditional
water harvesting system, check dams are built across the seasonally flooded gullies. In this system running
water is stored and diverted to the required
places such water does not remain stagnant for long,
hence there is less chance
of it becoming polluted
like that of pond water.
Question 3:
Find out the source of water in your region/locality. Is water from this source
available to all
people living in that area?
Answer 3:
In our locality water
is
available from the
following sources:
Ø
Through pipe line supply by municipal
corporation department to the houses.
Ø
People also obtain water
from hand pumps installed
nearby.
