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Old Tuesday, April 06, 2010
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Describe harmful effects of air pollution.

ANS :


* Burning sensation in eyes, nose and throat.
* Diseases of lungs like bronchitis, asthma, etc. caused by pollutant gases like SO2 and NO2.
* Diseases of respiratory system spread through dust particles. Silicosis is caused by silica and asbestosis is caused by asbestos.
* Cancer caused by carcinogenic pollutants.
* Heavy metals inhaled through air cause poisonous effects.
* Increase in ultraviolet radiation reaching earth due to depletion of ozone layer causes skin cancer, damage to eyes and damage to immune system.
* Dissolution of atmospheric gases like SO2, SO3, NO2 in moisture results in formation of sulphuric acid and nitric acid. This causes acid rain which harms organisms, various monuments and buildings.
* Carbon dioxide and methane absorb heat and increase the temperature of earth's atmosphere. This is known as Greenhouse effect. This increase in temperature results in melting of ice on polar regions and causes sea level to rise.
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  #42  
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ANSWER IN SHORT:


1. What does 'environment' mean ?

ANS :The social, economical, physical and chemical factors surrounding an organism are collectively known as 'environment' for that organism.
2. What is studied in environmental biology ?

ANS :The interrelationship between organisms as well as between living and nonliving components is studied in environmental biology.
3. Mention types of environment.

ANS :Types of environment are : (i)Physical environment (ii)Biological environment (iii)Cultural environment.
4. Mention the major reason for environmental problems.

ANS :Population explosion is the major reason for environmental problems.
5. Define : Pollution.

ANS :Pollution is an undesirable change in the physical, chemical or biological characteristics of air, water and soil.
6. Mention common pollutants.

ANS :Various gases, heavy metals, pesticides, fertilisers, radioactive materials, high temperature, etc. are major pollutants.
7. Mention types of pollution.

ANS :Air pollution, water pollution and land(soil) pollution.
8. What is atmosphere?

ANS :The transparent layer of gases surrounding the earth's surface is called atmosphere.
9. Mention common causes for air pollution.

ANS :Urbanisation, population explosion, industrialisation and heavy transportation are common causes for air pollution.
10. Mention respiratory diseases caused due to air pollution.

ANS :Asthma, bronchitis, silicosis and asbestosis are diseases caused due to air pollution.
11. Mention pollutants causing asthma and bronchitis.

ANS :SO2 and NO2 are pollutants causing asthma and bronchitis.
12. What are carcinogens ?

ANS :Substances causing cancer are called carcinogens.
13. What rae the effects of depletion of ozone layer ?

ANS epletion of ozone layer increases the amount of ultraviolet radiation reaching the earth which, in turn, causes skin cancer and damages eyes and immune system.
14. What is Greenhouse Effect ?

ANS :The warming up of earth's atmosphere due to absorption of heat by gases like CO2 and methane present in the atmosphere is called Greenhouse Effect.
15. Which type of pollutants cause air pollution ?

ANS :Gaseous and particulate pollutants cause air pollution.
16. What is water pollution ?

ANS :The mixing of undesirable chemical, physical or biological components with pure water is called water pollution.
17. What is the full form of BOD ?

ANS :The full form of BOD is Biological Oxygen Demand.
18. What is Eutrophication ?

ANS :The pollution caused due to growth of algae and other microorganisms under the influence of nutrients is called Eutrophication.
19. Which components promote algal growth in water ?

ANS :Compounds having nitrates and phosphates promote algal growth in water.
20. What is the full form of NEERI ?

ANS :NEERI stands for National Environment Engineering Research Institute.
21. Mention prime causes for land pollution.

ANS :Urbanisation, population explosion and industrialisation are prime causes for land pollution.
22. Mention solid waste pollutants causing land pollution.

ANS :Faeces of humans and other animals, dead bodies and domestic waste are solid pollutants causing land pollution.
23. How are pollutants classified ?

ANS :Pollutants are classified as biodegradable and non-biodegradable pollutants.
24. What is meant by biodegradable pollutants ?

ANS :The pollutants which can be decomposed by microorganisms are called biodegradable pollutants.
25. What is meant by non-biodegradable pollutants ?

ANS :The pollutants which cannot be decomposed by microorganisms are called biodegradable pollutants.
26. Give examples of biodegradable pollutants.

ANS :Faecal matter, solid sewage waste, domestic waste, agricultural waste, paper, wood, clothes, etc. are biodegradable pollutants.
27. Give examples of non-biodegradable pollutants.

ANS :Pesticides like DDT, mercury, lead, aluminium, arsenic, plastics, etc. are examples of non-biodegradable pollutants.
28. What is Biomagnification ?

ANS :The accumulation of harmful non-biodegradable substances in the bodies of organisms through the foodchains and biogeochemical cycle is called Biomagnification.
29. Demand of what increases due to population explosion ?

ANS emand of space and food increases due to population explosion.
30. What is conservation of environment ?

ANS :Conservation of environment means such activities which provide individual or commercial benefits by preventing excessive use leading to environmental damage.
31. Mention the effects due to depletion of ozone layer.

ANS :Increase in ultraviolet radiation reaching earth due to depletion of ozone layer causes skin cancer, damage to eyes and damage to immune system.
32. What work has been done by NEERI for water pollution ?

ANS :NEERI has developed Oxygen Pond method for the treatment of industrial effluents and sewage.
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Describe fission as a method of reproduction.

ANS :Fission occurs in unicellular organisms. Binary fission and multiple fission are its two types.

BINARY FISSION :


* An organism produces two unicellular organisms identical to the parent cell through mitotic division.
* Amoeba, paramoecium, etc. reproduce by binary fission.



MULTIPLE FISSION :


* Under certain circumstances, the nucleus of a cell divides several times within the cell forming many nuclei.
* Each nucleus is then surrounded by cytoplasm to form a separate unit.
* All these newly formed cells then come out of the mother cell(parent cell) by breaking the wall and behave as a new organism.
* Plasmodium, amoeba, paramoecium, etc. exhibit such reproductive event.
Attached Thumbnails
Short notes & explanation-amoeba01.jpg   Short notes & explanation-multifission.jpg  
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  #44  
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Describe budding as a method of reproduction.
ANS :


* Budding is observed in both unicellular and multicellular organisms.
* In unicellular organisms, some part of the body swells out at one point and developes into a 'bud' due to the formation of nucleus and cytoplasm within it. This bud then separates from the parent cell and behaves as an independent organism. Sometimes the buds form a chain before being separated. Example : yeast.
* In multicellular organisms like hydra, a part of its cylindrical body swells and develops into a bud. This bud then grows and separates from the mother's body to develop as an independent daughter animal.
Attached Thumbnails
Short notes & explanation-budding_yeast.jpg   Short notes & explanation-budding_hydra.jpg  
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Describe spore formation as a method of reproduction.

ANS :


* Spore formation is the most common method of asexual reproduction in majority of bacteria and fungi.
* During spore formation, a structure called sporangium develops from fungal hypha which is a filamentous structure.
* The nucleus in sporangium divides several times and forms many nuclei.
* Each nucleus gets surrounded by cytoplasm and forms small unicellular structure called spore.
* When sporangium bursts, the spores spread into the surrounding environment and germinate into new hypha forming mycellium which behaves as new organism.
* Mucor and Rhizopus reproduce by this method.
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Describe regeneration as a method of reproduction.

ANS :


* Regeneration is the ability of an organism to reproduce the lost parts of its body.
* When some body part of an organism breaks suddenly, a new part similar to the lost (broken) part is created at the point of breaking after some time.
* All broken parts thus develop into new organisms.
* Hydra, planaria, sponge and starfish reproduce by regeneration.
* Some filamentous algae increase their number by this method. Algae filaments break frequently and each broken piece develops into independent algae. This is called fragmentation.
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Describe vegetative propagation in detail.

ANS :


* Development of a new plant from root, stem or leaf is called vegetative propagation.
* Some higher plants exhibit this method of reproduction.
* Examples : (i)Development of buds from the root of sweet potato.(ii)Development of buds on potato tuber.(iii)Development of buds on the margin of bryophyllum leaf.
* Besides natural method, artificial vegetative propagation is also used to increase production. Cutting, layering and grafting are commonly used methods of artificial vegetative propagation.
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Describe various methods of artificial vegetative propagation.

ANS :


1. CUTTING :

* In this method, a piece of root, stem, leaf or sometimes a bud is sown in soil which develops into a new plant.
* The piece of the plant sown in the soil develops roots downwards in the soil and aerial organs in the external environment.
* this method is useful for large scale production which is greatly economical and profitable.
* Example : sugarcane, grapes, rose, phalsa.



2. LAYERING :

* In this method, a branch of stem of a plant is bent towards the soil in such a way that some part of the branch remains inside the soil and its tip remains outside.
* The part covered by the soil develops roots.
* When this part is detached from the parent plant, it grows independently into a new daughter plant.
* Example : Lemon, guaua, hibiscus, jasmine and bougainvillaea.
* In plants like strawberry and raspberry, sometimes a branch comes into contact of the soil naturally and develops as a daughter plant after producing roots.



3. GRAFTING :

* Grafting is a method in which two parts of different plants are joined together in such a way that they unite to grow as one plant.
* A part of an adult (mature) plant is tied up with a unit of soft plant to get early flowering in the soft plant.
* The portion of the plant having roots on which grafting is performed is called 'stock'.
* The portion of the plant which is grafted on the other plant is called 'scion'.
* By this method, desirable characteristics of different plants can be combined.
* This method is very useful for plants whose seeds have long dormancy period and poor germination capacity.
* Example : On the stock of lemon, a scion of lemon or orange can be grafted. This method is widely used to increase the production of mango.
Attached Thumbnails
Short notes & explanation-cutting.jpg   Short notes & explanation-grafting.jpg   Short notes & explanation-layering.jpg  
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Please make PDF file of these notes and send as an attached file.
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Old Wednesday, April 07, 2010
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EXPLAIN : TWINKLING OF STARS

ANS:




The density of the atmosphere is not uniform everywhere as the atmosphere consists of layers of different densities.


The layer at the lower altitude (near earth's surface) is colder and denser than the layer at higher altitude.


Due to this , the refractive index of atmosphere decreases continuously as we move up from the surface.


The star light keeps on bending towards the normal at every point of the atmosphere till it reaches our eyes.


Thus, as shown in the figure(refer to the figure given in the answer for TOTAL INTERNAL REFLECTION) the position of the star appears different from its actual position.


Moreover, the atmosphere is not stationary, i.e. the physical condition of the refractive medium keeps on changing every moment.


This results in continuous shifting of the apparent position of the star as well as variation in the intensity of its light.


This leads to TWINKLING OF STARS.


Unlike stars the planets do not twinkle because they are far closer than stars. Therefore, we can consider stars as point-sized source of light and planets as a collection of large number of point-sized sources (extended objects) of light such that they nullify twinkling effect.
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