Prayer Question No.1. Which way the does poet implore his Lord to lead him to? Ans. The poet implores his Lord to lead him to the way of truth. He also prays God to remove all his doubts and darkness of ignorance. Question NO.2. Name the blessings that the poet prays for? Ans. The poet prays for the path of truth. He prays for the nectar of knowledge. He also prays that his heart is surcharged with passion, zest, and hope. Above all, he implores his Lord to save him from sloth and infirmity. Question No.3. What is it that the poet wants to sing? Ans. The poet wants to sing those songs which will infuse life even into the dead and will inspire people to come under the same umbrage of love The poet wants to sing beautiful songs of love and brotherhood. He wants to motivate people to remove bitterness against each other. Question No.4. “Subject me not to the trials, shame not my human form”, explain? Ans. The poet shows his humble submission before his Lord....
OUR ENVIRONMENT
Basic Terms
Basic Terms
Environment: Anything which surrounds an organism is said to form its environment. The surrounding can be changed by the animal or plant itself. In simple words, environment is the sum total of all external conditions and influences that affect the life and development of an organism.
Ecology: It is the study of relationship between the organisms and the environment.
Habitat: It is the natural living condition of an organism or animal.
Biodegradable substances: These are those substances which are broken down into simpler, harmless substances in nature within due course of time by the biological process such as action of micro-organisms like certain bacteria.
Example: paper, wood, cloth etc.
Non-biodegradable substances: These are those substances which cannot be broken down into simpler, harmless substances in nature.
Example: DDT, plastics, polythene bags etc.
Biosphere: All ecosystems taken together make up the biosphere. Biosphere is the zone, including the earth’s surface, the adjacent atmosphere, and the underlying crust where life can exist.
Ecosystem: An ecosystem may be defined as a structural and functional unit of the biosphere in which living and non-living component interact together to form stable and self supporting system. The term Ecosystem was coined by
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| Ecosystem (Biotic & Abiotic Component) |
Components of ecosystem: There are two components of ecosystem.
Biotic component: Biotic component consists of living part of the environment such as plants, animals, human beings, micro-organisms etc.
Abiotic component:Abiotic component consists of non-living part of the environment such as air, water, soil etc.
Types of Ecosystem: There are two types of ecosystem.
Natural Ecosystems: These ecosystems operate in the nature by themselves without any human interference.
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| Natural Ecosystem |
Artificial ecosystems: These are maintained by man and hence are also termed man-made or made-engineered ecosystems.
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| Artificially Maintained |
Example:Croplands, orchards, gardens, parks etc.
Producers:
These are those organisms which can make their own food. This includes all green plants and certain blue-green algae. These organisms can utilise solar energy with the help of photosynthetic pigments to form glucose. Producers ultimately produce the food for all other members of the community.
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| Cycle of Ecosystem |
Consumers: All animals are consumers. They cannot make their own food. Therefore, they utilize materials and energy stored by the producers.
Example:
i. Primary consumers or Herbivores.
i ii. Secondary consumers or Carnivores.
ii iii. Tertiary consumers or omnivores.
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| Types of Consumers in Food Chain |
Decomposers: These are those organisms which feed on dead decaying matter. These include bacteria and fungi.
Functions of decomposers:
1. Decomposers cleanse the earth of organic remains and can therefore, are termed as natural scavengers.
2. Decomposers create space for newer generations of organisms.
3. Decomposers release minerals and other raw materials trapped in organic matter.
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| Role of Decomposers |
Food Chain:
Food chain is a sequential interlinking of organisms based on their feeding habit. In simple words, a list of living organisms showing “who eats whom” is called a food chain.
i.e., Example:
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| Food Chain |
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| Food Chain |
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| Food Chain |
Properties of food chain:
1. Usually, there are four or five tropic levels in a food chain.
2. A food chain is always straight and proceeds in a progressive straight line.
3. In a food chain, there is unidirectional flow of energy.
4. Shorter food chains provide more available energy, while longer ones provide little available energy.
5. Only 10% of the energy available at each tropic level is transferred to the higher level.
Food Web:
Food web is a network of food chains which are interconnected at various tropic levels so as to form a number of feeding connections.
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Difference between Food chain and Fod web |
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| Food web |
Properties of food web:
1. Unlike food chains, food webs are never straight.
2. A food web provides alternative pathways of food availability.
3. Greater alternatives available in a food web make the ecosystem more stable.
4. Food webs also help in checking the overpopulations.
5. Food webs also help in ecosystem development.
Flow of energy in an ecosystem:
1. The ultimate source of entire energy, used by living organisms, is the sun.
2. Of the total solar radiations falling on the earth, only about 1% are captured by green plants in a terrestrial ecosystem and converted into food energy by photosynthesis. This energy is stored as chemical energy of food and finally used by the consumers.
10% Law:
It was put forth by Lindeman (1942). It is also termed as second law of thermodynamics or law of entropy. According to this law, on an average, only about 10% of energy is actually available to the next tropic level.
Biological Magnification:
The phenomenon that involves progressive increase in concentration of harmful non-biodegradable chemicals at different tropic levels in a food chain is called biomagnifications.
In simple words, some harmful non-biodegradable chemicals such as mercury, Cadmium etc. enter the bodies of organisms through the food chains and go on concentrating at each tropic level. This phenomenon is called bio-magnification or biological magnification.
Ozone and its Importance:
Ozone (O3) is a form of oxygen. It is formed by three atoms of oxygen.
In the stratosphere, ozone is being photo dissociated and generated by the absorption of harmful, ultraviolet (UV) radiations coming from sun.
Ozone layer is very important for the existence of life on earth because it absorbs most of the harmful ultraviolet radiations coming from the sun and prevents them from reaching the sun.
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| Ozone Depletion |
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| Ozone layer and its Depletion |
Ozone depletion and its cause:
The thinning of ozone layer is commonly called ozone depletion. Ozone is being depleted by air pollutants like CFCs (chlorofluorocarbons), methane (CH4) and oxides of nitrogen (NO). The excessive use of the fossil fuels and other air pollutants is also one of the major cause of the ozone depletion. The hole in the ozone layer called as ozone hole was first discovered over Antarctica in 1985.
Harmful Effects of Ozone depletion:
The ozone depletion has following harmful effects.
1. Ultraviolet radiations cause skin cancer.
2. These cause damage to eyes and also can cause increased incidence of cataract disease in eyes.
3. These cause damage to immune system.
4. Ozone depletion also causes global rainfall and ecological disturbances.
Wastes and moles of waste disposal:
“Waste disposal” literally means “getting rid of waste”.
Some prominent methods of waste disposal are:
1. Landfills: In urban areas, majority of the solid wastes are buried in low lying areas to level the uneven surface of land. This method of waste disposal is commonly called landfills.
2. Recycling of Wastes: Number of solid wastes (paper, plastics, metals, etc) can be recycled by sending them to respective recycling units.
3. Preparation of Compost:Household waste such as peeling of fruits and vegetables can be converted into compost and used as manure.
4. Incineration: Incineration is the process of burning of substances at high temperature and ultimately converting them into ashes. It is carried out in an incinerator.
5. Production of biogas and manure:Biodegradable wastes can also be used in biogas plants to generate biogas and manure.
NCERT Solutions
1. Why are some substances
biodegradable and some non-biodegradable?
Ans. Substances which can be
decomposed and broken down to simpler substances by micro-organisms acting on
it is called bio-degradable and those substances which cannot be acted upon by
microorganisms and are not broken down into simpler substances are called
non-biodegradable substances.
2. Give any two
ways in which bio-degradable substances would affect the environment.
Ans. Two ways in which
bio-degradable substances would affect the environment are:
(i)
During decomposition of the substances lot of foul smell spreads in the
surrounding areas.
(ii)
The place where these bio-degradable substance are present with some moisture
becomes breeding ground for insects like mosquitoes, housefly which are vectors
in carrying parasites that cause different diseases.
3. Give any two ways in which non-biodegradable
substances would affect the environment.
Ans. (i) The non-biodegradable
substances get accumulated and doesn’t get decomposed hence it remains in
the ecosystem and causes pollution, chokes the system of many animals and kill
them
(ii) These substances due to
accumulation cause water and soil pollution e.g., pesticides, detergents,
polythene.
4. What are trophic levels? Give an example of a
food chain and state the different trophic levels in it.
Ans. The various levels or
stages in a food chain at which the transfer of food takes place is called
trophic level, e.g., food chain.
Grass →
Grasshopper → frog → snake → peacock
Grass
— Producer — trophic level. 1
Grasshopper
— Consumer (Herbivores) — II trophic
level’.
Frog
— Consumer (Carnivores) — III trophic level
And
so on..
5. What is the role of decomposers in the ecosystem?
Ans.
1. Decomposers
cleanse the earth of organic remains and can therefore, are termed as natural
scavengers.
2. Decomposers
create space for newer generations of organisms.
3. Decomposers
release minerals and other raw materials trapped in organic matter.
4. Decomposers maintain balance in the
nature and plays an important role in the environment.
5. Decomposers add nutrients to the soil
once they are dead.
6. What is ozone and how does it affect any
ecosystem?
Ozone (O3)
is a form of oxygen. It is formed by three atoms of oxygen.
In the
stratosphere, ozone is being photo dissociated and generated by the absorption
of harmful, ultraviolet (UV) radiations coming from sun.
UV radiations from sun
Ozone
Ecosystem:
At ground level ozone is poisonous
but at higher level it is very useful as it protects all living organisms from
harmful UV radiations of the sun. It doesn’t allow , the ultra violet radiations
to enter the surface of earth. The UV radiations cause ionizing effect that
leads, to skin cancer in human beings.
7. How can you help in reducing the problem of waste
disposal? Give any two methods.
Ans. To reduce the. problem of
waste disposal we can
(i)
Segregate the. bio-degradable waste from non-biodegradable waste before dumping
it.
(ii)
Remove all materials which can be recycled and send it for recycling. e.g.,
paper, glass, metal, rubber.
QUESTIONS FROM NCERT TEXTBOOK
1. Which of the
,following groups contain only biodegradable items?
(a)
Grass, flowers and leather
(b)
Grass, wood and plastic
(c)
Fruit-peels, cake and lime juice (a), (c) and (d).
(d)
Cake, wood and grass
Ans. (a), (c) and (d).
2. Which of the
following constitute a food-chain?
(a)
Grass, wheat and mango (b)
Grass, goat and human,
(c)
Goat, cow and
elephant (d)
Grass, fish and goat,
Ans. (b) Grass, goat and human
3. Which of the
following are environment friendly practices?
(a)
Carrying cloth-bags to put purchases in while shopping
(b)
Switching off unnecessary lights and fans
(c)
Walking to school instead of getting your mother to drop you on her scooter
(d)
All of the above
Ans. (d) All of the above
4. What will happen if we kill all the organisms in
one trophic level?
Ans. If all the organisms in one
trophic level are killed then all the organisms of next trophic level which are
dependent on these are killed. Next trophic levels will not get food to eat and
the entire food chain gets disturbed. At the same time the organisms at the
lower trophic level will reproduce and the population will increase in
abundance there by , disturbing the ecosystem.
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?
Ans. The impact of removing all
the organisms in a trophic level will be same. If the organisms of any trophic
level be removed it will certainly damage the ecosystem.
For
example,
Grass
→ Grass hopper Frog → Snake → Peacock
In
this if all grasshoppers are killed/removed frogs will strive and grass will
reproduce in abundance.
If
snakes are removed then the number of frogs will increase which will disturb
the entire ecosystem.
1. What is biological
magnification? Will the levels pf this magnification ,bed different at
different levels of the ecosystem?
Ans.
Biological Magnification:
The phenomenon that involves progressive increase in concentration of
harmful non-biodegradable chemicals at different tropic levels in a food chain
is called biomagnifications.
In simple words, some harmful
non-biodegradable chemicals such as mercury, Cadmium etc. enter the bodies of
organisms through the food chains and go on concentrating at each tropic level.
This phenomenon is called biomagnifications or biological magnification.
The
level of magnification will be different at different trophic levels, the
maximum concentrations will be at the highest trophic level and the chemical
will be less at lower trophic levels.
7. What are the problems caused by the
non-biodegradable waste that we generate?
Ans. As the non-biodegradable
waste cannot be broken down into simpler forms hence they keep on accumulating and will cause following effects :
(ii)
They cause lot diseases.
(iii)
It also causes biological magnification.
iii) They will increase the
pollution level
8. If all the waste we generate is bio-degradable,
will this have no impact on the environment?
Ans. If all the waste we
generate is bio-degradable and is managed in such a way that it is allowed to
decompose then it will have no impact on the environment.
9. Why is damage to the ozone layer a cause for
concern? What steps are being taken to limit this damage?
Ans. Ozone layer in the stratosphere
is very helpful in shielding harmful UV rays. In absence of ozone layer heavy
damage to organism may occur. It may cause diseases like skin cancer, cataract,
reduced crop production etc.
The
damage is limited bye UNEP (United Nations Environment Programme), it has
forged an agreement to freeze for CFC production in 1986.
CFC–
Chlorofluorocarbons used as refrigerants and in fire extinguishers.
With Regards
Riya Gupta
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