CBSE Questions for Class 12 Medical Biology Environmental Issues Quiz 12 - MCQExams.com

What is the importance of forest as a resource?
  • It improves water holding capacity of soil.
  • It provides habitat, food, protection to wild life.
  • It help in balancing $$CO_{2}$$ and $$O_{2}$$ of atmosphere.
  • All of the above.
If forest cover is reduced to half, what is most likely to happen on a long term basis? 
  • Tribals living in these areas will starve to death.
  • Domestic animals in these and joining areas will die due to lack of fodder.
  • Large biomes will become deserts.
  • Crop breeding programes will suffer due to a reduced ability of variety of germplasm.
An important product in the ozone depletion by chlorofluorocabons is
  • $$ Cl_2$$
  • $$ OCl $$
  • $$ F_2 $$
  • $$ O_2F_2 $$
What is the intensity of sound in normal conversation : -
  • 10 - 20 decibel
  • 30 -  60 decibel
  • 70 -  90 decibel
  • 120 -150 decibel
In which one of the following, the BOD (Biochemical Oxygen Demand) of sewage (S), distillery effluent (DE), paper mill effluent (PE) and sugar mill effluent (SE) have been arranged in ascending order
  • SE < S < PE < DE
  • SE < PE < S < DE
  • PE < S < SE < DE
  • S < DE < PE < SE
Ozonosphere occurs at height of
  • 8-10 km. above poles
  • 8-10 km. above equator
  • 11-16 km above poles
  • 11-16 km above equator
One of the most dangerous radioactive pollutant to Homo sapiens is
  • Strontium - 90
  • Phosphorus - 32
  • Sulphur - 35
  • None of the above
In 'Wet System' of removing gaseous-pollutants  
  • Alkali fluid is used.
  • Acidic fluid is used.
  • Neutral fluid is used.
  • None of the above.
A lake with an inflow of domestic sewage, rich in organic waste, may result in
  • Drying of the lake very soon due to algal bloom
  • An increased production of fish due to lot of nutrients
  • Death of fish due to lack of oxygen
  • Increased population of aquatic web organisms
Fourier predicted the green house effect and it was coined by
  • Fourier
  • Tanseley
  • Arrhenius
  • Odum
The molecular action of ultra violet light is mainly reflected through
  • Photodynamic action
  • Destruction of hydrogen bonds between DNA strands
  • Formation of pyridine
  • Destruction of ester bonds
Which of the following damages WBC bone-marrow and lymph nodes? 
  • I$$^{131}$$
  • Ca
  • Cesium
  • Strontium
Which prokaryotic organism is frequently used in laboratories for testing the given phenomenon?
226814_81323d17fc3640deba5fd3ae2b9d0626.png
  • Amoeba
  • Paramecium
  • Escherichia coli
  • Agrobacterium tumefaciens
These are the green house gases match their exact concentration in the environment. 
1 - 
Methane
2 - CFCs
3 - N$$_2$$O
4 - Carbon dioxide
  • A- 2, B- 4, C- 1, D- 3
  • A- 3, B- 4, C- 1, D- 2
  • A- 1, B- 2, C- 3, D- 4
  • A- 4, B- 2, C- 1, D- 3
Contamination of radioactive materials are dangerous because it causes 
  • Biological magnification
  • Gene mutation
  • Photochemical smog
  • Ozone distruction
Which of the following radioactive element is found in tobacco smoke? 
  • lodine-131
  • Polonium-210
  • Caesium-137
  • Strontium-90
Leukaemia is caused by
  • Ca 40
  • Sr 90
  • Caesium
  • Iodine
What is being depicted in this graph?
226793_490cb0dbaec8486fac8ece8c3eaf64e0.png
  • Green house gases
  • Mineral rich water
  • BOD
  • Oligotrophic pond
The antiknock agent added to unleaded petrol is
  • Tetraethyl lead
  • Tetramethyl lead
  • Dibromoethane
  • Methyl Tertiary Butyl Ether (MTBE)
Contribution of methane to global warming is 
  • 6%
  • 14%
  • 20%
  • 30%
In a survey conducted in Delhi, on the efforts being made to clear the Km patch in Yamuna, it was observed that the BOD in 2003 was 13 mg/litre while it was 18 mg/litre in 2004. 
What inference can you draw from the following data?
  • The pollutants in the river has decreased due to efforts by Delhi government.
  • Despite efforts there are still dissolved minerals in the river.
  • Although efforts are being made, the pollution is still on an increase in Delhi.
  • There is an algae in the river.
Which one of the following is not a device used to control a particulate matter? 
  • Arresters
  • Scrubbers
  • Filters
  • Electrostatic precipitator
  • Incinerator
Which of the following property of green house gases may lead to ill effects?
  • Transparent to emission from earth surface for passage to outer space
  • Transparent to both solar and longwave radiations from earth
  • Absorption of long wave radiations from earth
  • Absorption of polar radiations for warming the atmosphere
CO$$_2$$, CH$$_4$$, N$$_2$$O and CFCS are called as green house gases because they can absorb
  • Ultraviolet radiation
  • Long wave infrared radiation
  • Visible light radiation
  • X-rays radiation
  • $$\gamma$$-rays radiation
Chlorofluorocarbons are not recommended to be used in refrigerators, because they
  • Increase temperature
  • Depletes ozone
  • Affects environment
  • Affects human body
Which among the following are the consequences of ozone depletion?
  • Entry of UV-rays in earth's atmosphere
  • Various skin troubles like skin cancer
  • Cataract
  • All of the above
The gases which absorb most of IR (infrared) rays are 
  • SO$$_2$$, CO$$_2$$, and NO$$_2$$
  • SO$$_2$$, CH$$_4$$, and O$$_3$$
  • CO$$_2$$, CH$$_4$$, and CFCs
  • NO$$_2$$, CO$$_2$$, and O$$_3$$
Which of the following is a weightless pollutant? 
  • Sewage and exhaust emissions
  • SO$$_2$$ and NO$$_2$$
  • Photochemical smog
  • Heat, sound and radioactive wastes
Man made radio active element Sr$$^{90}$$ accumulates in the body through 
  • Air
  • Food web
  • Water
  • Contaminated soil
Increase of BOD in water leads to
  • Increase in the dissolved oxygen concentration
  • Decrease in the dissolved oxygen concentration
  • Maintenance of dissolved oxygen concentration at the same level
  • No effect on dissolved oxygen concentration
Which one of the following is responsible for causing skin cancer and mutation? 
  • Ozone depletion
  • Smog formation
  • Snowfall
  • Smoke from aeroplane
Which of the following strategy is not a correct approach to reduce global warming?
  • Reducing the greenhouse gas emission by limiting the use of fossil fuels.
  • Increase the vegetation cover particularly the forest for photosynthetic utilization of CO$$_2$$.
  • Minimizing the use of nitrogen fertilizers in agriculture for reducing N$$_2$$O emission.
  • Increasing the use of air conditioners, refrigeration unit and production of plastic foams and propellants in aerosol spray cans.
  • Developing substitutes for chlorofluorocarbons.
Sewage drainage into water bodies is harmful for fishes because
  • Excessive CO$$_2$$ is added in water.
  • It gives off a bad smell.
  • It removes the competition with fishes to dissolved oxygen.
  • It increase competition of fishes for dissolved oxygen.
Limit of B.O.D. prescribed by Central Pollution Control Board for the discharge of industrial and municipal waste waters into natural surface waters, is 
  • < 30 ppm
  • < 3.0 ppm
  • < 10 ppm
  • < 100 ppm
High BOD indicates
  • Highly polluted $$H_2O$$
  • Less pollution in $$H_2O$$
  • Less sewage
  • Less microorganism
The gas that causes the depletion of the ozone layer thereby allowing more UV radiations to reach the Earth is
  • Carbon dioxide 
  • Chlorofluorocarbon 
  • Oxygen 
  • Nitrous oxide 
Exposure of plants to high fluoride concentration results in necrosis or chlorosis characteristically in 
  • Petiole but not in lamina
  • Only mid rib in lamina
  • Leaf tip and leaf margins
  • Stem tips only
In a coal fired power plant electrostatic precipitators metabolites are installed to control emission of 
  • CO
  • $$SO_2$$
  • $$NO_x$$
  • SPM
In a sewage plant, BOD is indicated as high. After sometime it shows a decrease then
  • There is increase in bacterial growth but decrease in oxygen.
  • There is decrease in bacterial growth but increase in oxygen.
  • There is increase in bacterial growth but increase in oxygen.
  • There is decrease in bacterial growth but decrease in oxygen.
Genetic erosion is due to
  • Deforestation
  • Shifting cultivation
  • Adoption of genetically uniform varieties of crop
  • All of the above
What is not useful to increase agriculture production?
  • Mechanisation of agriculture
  • Enhanced irrigation facilities
  • Use of fertilizers
  • Deforestation
Which one of the following is the chief ozone-depleting substance used in refrigerators and air conditioners as coolant?
  • Chlorofluorocarbons (CFCs)
  • Carbon tetrachloride
  • Methyl chloroform
  • Methyl bromide
Drinking mineral water drink with low levels ($$\sim$$ 0.02 ppm) of pesticide for long period would
  • Cause cancer of intestine.
  • Lead to accumulation of pesticides in the body.
  • Cause leukaemia in most of the people.
  • Produce immunity against mosquito.
Ozone hole enhances
  • UV radiations reaching earth
  • Number of cataracts
  • Skin cancers
  • All of the above
Ozone protects biosphere from high energy
  • Infra-red rays
  • Ultraviolet rays
  • X - rays
  • Gamma rays
Multiple Choice Questions
Consider the following statements (i-iv) about organic farming:
(i) Utilizes genetically modified crops like Bt cotton
(ii) Uses only naturally produced inputs like compost
(iii) Does not use pesticides and urea
(iv) Produces vegetables rich in vitamins and minerals.
 Which of the above statements are correct?
  • (ii), (iii) and (iv)
  • (iii) and (iv) only
  • (ii) and (iii) only
  • (i) and (ii) only
Chlorofluorocarbon releases a chemical harmful to ozone
  • Fluorine
  • Sulphur dioxide
  • Nitrogen peroxide
  • Chlorine
In the recent years, there has been an increasing incidence of floods in the plains of northern India, because
  • There has been an increase in annual rainfall.
  • The rate of silting of dams has gone lip.
  • There has been increased deforestation in the catchment areas.
  • Increased areas of land is being self cultivated.
In the environment, ozone is known for its 
  • Harmful effects
  • Useful effects
  • Both A and B
  • Inert nature
CFCs used in refrigerators cause 
  • Water pollution
  • Ozone depletion
  • Acid rain
  • Photochemical smog
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