|
Environment & Ecosystem |
Environment: Sum total of Physical and
Biological world around us. Ecosystem: Functional unit of the environment. First
time defined by A.G Tansley |
|
Components of Ecosystem |
Biotic Components: It consists of Producers, Primary Consumers, Secondary
Consumers, Decomposers Abiotic Components: It consists of all non-living factors of ecosystem e.g.
Temperature, Soil, Rainfall, Minerals |
|
Biodegradable and Non-Biodegradable pollutants |
Biodegradable: Compost, Dung, Wool, Leather, Paper,
Cotton, Jute etc. Non- Biodegradable: Plastic, Polythene, Pesticides
(DDT), Radioactive materials, Metals etc. |
|
Food Chain |
Sequential interlinking of organisms that involve transfer
of energy by eating or being eaten. e.g. Plant -> Sheep -> Human |
|
Food Web |
Interconnected network of many food chains which provides
alternate options for living organism to consume. Food web makes ecosystem stable |
Trophic Levels |
Trophic level defines the position of an organism in a food chain. Plants occupy first Trophic level, Herbivores occupy second Trophic level and Carnivores occupy third Trophic level |
|
Ecological Pyramids (Given by Charles Elton) |
Ecological Pyramid is the graphical representation of energy
level, biomass or number at each Trophic level. It is of many types: Ø Pyramid
of Number Ø Pyramid
of Biomass Ø Pyramid
of Energy |
|
Flow of Energy in an ecosystem |
Energy flow in an ecosystem is unidirectional. Sun is ultimate source of energy which passed energy to
plants. The plants in turn transfer energy to Primary consumers which transfer
energy to secondary consumers. |
|
Lindeman’s law of 10% |
The Law states that only 10% of energy is transferred to
next Trophic level in a food chain. |
|
Bio magnification |
The Progressive increase in the harmful chemicals in
the food chain due to pollution. |
|
Ozone layer depletion |
Ozone (O3) is found in stratosphere and protects
us from UV radiations. Depletes due to Chloro-flouro-Carbons (CFCs) such as
CCl4. Montreal Protocol (1987) signed to ban use of CFCs. |
|
Waste Management |
Follow 3Rs: Reduce, Reuse, Recycle Compost Landfills Incineration Sewage treatment |
Ans: Ecosystem is defined as interaction of biotic community with environment.
The flow of energy and matter takes place at ecosystem.
Ecosystem was first defined by A.G. Tansley and has biotic and abiotic components.
1. Biotic components: It includes all living beings such as plants, animals, microbes.
The biotic components are divided into:
a. Producers: They produce organic matter from inorganic compounds. E.g Plants, Blue-green Algae.
b. Consumers: They depend on producers for food. They can be herbivores, carnivores or omnivores.
c. Decomposers: They convert dead matter into simple compounds and release it into soil.
2. Abiotic components: It is the physical environment in which the living beings sustain. It includes climatic factors such as temperature, rainfall, wind, soil
It also includes inorganic and organic compounds.
Q. Define the term Food chain?
Ans: Food chain is defined as sequence of interlinked organisms who eat other or are being eaten.
Food chain involves the transfer of energy.
Each step of food chain represents a trophic level.
E.g Grass --------> Deer -------> Lion
Q. What is Food web?
Ans: Food web is interconnected network of many food chains.
In a food web, an organism can be eaten by more than one organism.
Food webs provide alternate pathways and make an ecosystem stable.
Q. What is biomagnification?
Ans: Biomagnification is defined as proportional increase of harmful chemical substances in higher trophic levels. E.g DDT.
Ans: The Energy flow in an ecosystem is always unidirectional.
In an ecosystem, usually Sun is ultimate source of energy which passed energy to plants.
The plants in turn transfer energy to Primary consumers which transfer energy to secondary consumers. and so on.
Ans: Lindermans Law states that only 10% of energy is transferred to next Trophic level in a food chain. The other 90 Percent is wasted as heat energy.
Q. Why are some substances biodegredable and some substances non biodegredable?
Ans: The biodegradable substances have biological origin. Therefore, enzymes from bacteria and fungi can degrade them. E.g Sewage, Paper, Wood.
The non biodegradable substances are elements or chemically prepared. Therefore, enzymes from bacteria and fungi cannot degrade them. E.g Plastic, Iron.
Q. What are trophic levels?
Ans: The distinct sequential steps in food chain where transfer of energy takes place.
E.g In a food chain,
Plant ----> Sheep -----> Man
Plant belongs to first trophic level. Goat belongs to second trophic level and Man belongs to third trophic level.
Q. What is the role of decomposers in an ecosystem?
Ans: Decomposers such as bacteria and fungi feed upon dead matter and convert it back into simple substances, which are then released into ecosystem.
Decomposers help in recycling of nutrients.
Without decomposers, an ecosystem will not sustain.
It is of many types:
Ø Pyramid of Number
Ø Pyramid of Biomass
Ø Pyramid of Energy
Q. What is ozone? How does it affect ecosystem?
Ans: Ozone is a molecule of oxygen (O3). It forms a layer in stratosphere and blocks Ultraviolet rays of sun from reaching earth. The Ultraviolet rays will kill living organisms by causing mutations. These rays can cause skin cancer, cataracts, and will destroy ecosystems.
Ans: The various steps that need to be taken to prevent ozone damage include:
i. less use of all the appliances that use ozone depleting substances like CFC's, Halons.
ii. Use ozone friendly alternatives of CFC's
iii. Follow Montreal protocol
Q. What will happen if we kill all organisms in one trophic level?
Ans: In a food chain, the energy transfer takes place from one trophic level to another.
If all organisms in one trophic level are killed, the whole food chain will collapse.
Q. How can you help in reducing the problem of waste disposal?
What are various methods of waste management?
Ans: The waste can me managed by various methods:
1. Landfills: The waste is buried in low lying areas or huge pits.
2. Incineration: The waste is burned at high temperature and converted into ashes.
3. Recycling of waste: Paper, plastic, metals can be recycled to be used again.
4. Compost: The organic waste is collected in compost pit where it decays to form manure.
Q. Why
are fossil fuels classified as nonrenewable sources of energy?
Ans: Fossil
fuels are classified as Nonrenewable sources of energy as they cannot be
replaced in the nature and are available in limited amount e.g Coal, Petrol,
Natural gas.
Q. What
is Biomass? Give three examples of it.
Ans: The dead parts, waste matter or products of living organisms is called as Biomass. E.g Wood, Cow Dung, Fodder.
Q. What are the problems caused by the non biodegradable wastes that we generate?
Ans: Non Biodegredable waste is the type of waste which cannot be decomposed by the bacteria and fungi e.g. Plastic, Polythene, Metals etc.
Biodegredable waste pollutes the environment
They make the soil infertile
It remains in the environment for long period of time.
Objective Type Questions:
A. Grass, Flowers, Leather
B. Grass, Wood, Plastic
C. Fruit peels, Cake, Lime Juice
D. Cake, Wood, Grass
Ans: A, C ,D
Q. Which of the following constitue a food chain?
A. Grass, Wheat and Mango
B. Grass, Wheat and Humans
C. Goat, Cow and elephant
D. Grass, Fish and Goat
Ans: B. Grass, Goat and Human
Q. Which of 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: All of the above
A. Human greed
B. Dumping of domestic garbage
C. Illegal encroachment
D All of above
Ans: All of above
Q. Average value for amount of organic matter that is present at each step or level of food chain:
a. 20% b. 10% c. 30% d. 40%
Ans: b. 10%
a. Ozone layer b. Environment
c. Atmosphere d. Ecosystem
Ans: b. Environment
Q. Of the total amount of energy that passes from one trophic level to another in food chain, about 10% is
A. Transpired
B. Burnt in respiration
C. Stored in body tissues
D. Loss as heat
Ans: C. Stored in body tissues
Q. Ozone is present in which of following layers of atmosphere?
A. Mesosphere B. Troposphere
C. Stratosphere D. Thermosphere
Ans: C. Stratosphere
Q. In a garden ecosystem,which of following are producers?
A. Snakes B. Insects
C. Rabbits D. Grasses, flowering plants
Ans: D. Grasses, flowering plants
Q. The term ecosystem was coined by
A. Haldane B. Odum
C. Tansley D. Oparin
Ans: C. Tansley
Q. Global warming is a result of increase percentage of .............. in atmosphere
a. Carbon dioxide b. Carbon monoxide
c. Oxides of nitrogen d. Sulphur
Ans: A. Carbon dioxide
Q. Natures cleaners are:
A. Producers B. Consumers
C. Decomposers D. Carnivores
Ans: C. Decomposers
Q. Which organism is a decomposer?
A. Vulture B. Fungus
C. Fox D. Frog
Ans: B. Fungus
Q. In a food chain, there is ............. flow of energy
A. Bi directional B. Zig zag
C. Uni directional D. Multi directional
Ans: C. Unidirectional
Q. Biotic components include:
A. Producers only
B. Consumere only
C. Producers and consumers
D. Producers, comsumers and decomposers
Ans: D. Producers, comsumers and decomposers
Q. Importance of ecosystem lies in:
A. Flow of energy
B. Cycling of materials
C. Both A and B
D. None of these
Ans: Both A and B
Q. 10% energy transfer law was first given by
A. Tansley B. Lindeman
C. Elton D. Raunkier
Ans: Lindeman
Q. Name any four common waste disposal methods?
Ans:
1. Landfill
2. Composting
3. Incineration
4. Vermicomposting
Reason: The length and complexity of food chain vary greatly
Ans: B. Both are Correct, But R is not correct explanation of A
Ans: The two examples of food chain are,
1. Grass _____ Deer ______ Lion
2. Grass ______ Insect _____ Bird
Q. Which of following constitutes a food chain:
a. Grass, Wheat and Mango b. Goat, Cow, elephant
c. Grass, Goat and Human d. Grass, Fish and Goat
Ans: c. Grass, Goat and Human
Q. In a food chain, the initial organism is usually:
a. Photosynthetic b. Herbivore c. Saprophytic d. Parasitic
Ans: a. Photosynthetic
Q. In a food chain, the third trophic level is always occupied by:
a. Carnivore b. Decomposers c. Herbivores d. Producers
Ans: a. Carnivore
Q. One of the following is not a consumer below:
a. Giraffe b. Antelope c. Algae d. Alligator
Ans: c. Algae
Q. In a food chain comprising of snakes, grass, insects and frog, the secondary consumer is :
a. Insect b. Snake c. Frog d. Grass
Ans: c. Frog
Q. List two Non-Biodegradable pollutants.
Q. Which factor is mainly responsible for increase in demand of natural resources?
A. Scientific advancement
B. Increase in population
C. Environmental pollution
D. Use of Biodegradable chemicals
Ans: B. Increase in population
Ans: It is very necessary to replace these non-biodegradable items by disposable paper items because they pollute land and water resources. They are also not decomposed by bacteria.
Q. In our day-to-day life we come across many items like polythene bags, vegetable peels etc. Make a list of at least seven items from your surroundings which are biodegradable.
Ans: Paper, Food waste, Human waste, Manure, Sewage sludge, dead animals and falling plant parts.
Reason: Cultivation of land and grazing are allowed in national parks.
(a) Both, A and R, are true and R is the correct explanation of A
(b) Both, A and R, are true but R is not the correct explanation of A
(c) If A is true but R is false
(d) If A is false but R is true
Ans: (c) A is true but R is false
a) Every component of food chain forms trophic level
b) Interrelation between different food chains is food web
c) All chains formed by nutritional relations are used to
understand energy flow
d) Energy level increases from lower trophic level to higher
trophic level.
Ans: d) Energy level increases from lower trophic level to
higher trophic level.
Q. In natural ecosystem, decomposers include:
a. All microscopic organisms b. Bacteria and Fungi c. Only Bacteria d. Only Fungi
Ans: b. Bacteria and Fungi
Q. The decomposers in an ecosystem:
a. Convert inorganic material to simpler forms b. Convert organic material to inorganic forms
c. Convert inorganic materials into inorganic compounds d. Do not break organic compounds
Ans: b. Convert organic material to inorganic forms
Q. In an ecosystem, the 10% of energy available for transfer from one trophic level to the next is in the form of:
a. Heat energy b. Chemical energy c. Light energy d. Mechanical energy
Ans: b. Chemical energy
Q. Assertion: Food web is a network of food chains which are interconnected at various trophic level
Reason: In a food web, one organism may occupy more than one position
A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true and R is not the correct explanation of A
C. A is True, R is False
D. A is False, R is True
Ans: B. Both A and R are true and R is not the correct explanation of A
Q. Assertion: Decomposers are micro consumers
Reason: They bring mineralization of decomposed matter
A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true and R is not the correct explanation of A
C. A is True, R is False
D. A is False, R is True
Ans: A. Both A and R are true and R is the correct explanation of A
Q. Assertion: There is always interaction between ecosystem
Reason: An ecosystem is recognized as self-regulating and self-sustaining entity.
A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true and R is not the correct explanation of A
C. A is True, R is False
D. A is False, R is True
Ans: A. Both A and R are true and R is the correct explanation of A
Q. The use of which chemical has endangered the ozone layer ?
(A) Pesticides (B) CFCs (C) Insecticides (D) None of these
Ans: (B) CFCs
Q. Assertion (A): Decomposers act as cleaning agents of the environment.
Reason (R) : The decomposers recycle waste material in the hydrosphere.
Ans: (C) A is true but R is false.
