CBSE Questions for Class 12 Medical Biology Environmental Issues Quiz 3 - MCQExams.com

Increase of BOD in water leads to
  • Increase in the dissolved O$$_{2}$$ concentration.
  • Decrease in the dissolved O$$_{2}$$ concentration.
  • Maintenance of dissolved O$$_{2}$$ concentration at the same level.
  • No effect on dissolved O$$_{2}$$ concentration.
In a coal power plant, electrostatic precipitators are installed to control emission of
  • $$SO_2$$
  • $$NO_2$$
  • SPM
  • CO
Which of the following strategy is not useful for global warming?
  • Use of fossil fuel in limit
  • Increase in forest
  • Increasing use of nitrogen fertilizers
  • Use of other options in the place of CFC
Which one of the following gases can deplete ozone layer in the upper atmosphere?
  • Ammonia
  • Methane
  • Carbon monoxide
  • None of the above
Bio-indicators are used for
  • Oxygen demand
  • Air pollution
  • Mineral present
  • All of the above
The BOD of an eutrophied lake will be
  • Higher
  • Lower
  • Moderate
  • Same as any other lake
Electrostatic precipitators are extensively employed to control
  • Water pollution
  • Air pollution
  • Radioactive pollution
  • None of the above
When domestic sewage mixes with river water
  • Small animals like rats will die after drinking river water.
  • The increased microbial activity releases micro nutrients such as iron.
  • The increased microbial activity uses up dissolved oxygen.
  • The river water is still suitable for drinking as impurities are only about 0.1%.
What will be the effect of addition of organic material on water?
  • COD remain unaffected
  • BOD remain unaffected
  • Increases BOD
  • Reduces BOD
Measuring 'Biochemical Oxygen Demand' is used for
  • Estimating the amount of organic matter in sewage water.
  • Working out the efficiency of oil driven automobile engines.
  • Measuring the activity of Saccharomyces cerevisiae in producing curd on a commercial scale.
  • Working out the efficiency of R.B.Cs. about their capacity to carry oxygen.
If we remove half of the forest cover of earth, what kind of crisis will occur?
  • Many species would become extinct.
  • Population, pollution and ecological imbalance will rise.
  • Energy crisis will commence.
  • The remaining forest will cause imbalance.
If forest area is reduced to half, which one of the following will be long term effect?
  • The natives (tribals) of that area will die on account of hunger.
  • Cattles of that area will die due to scarcity of fodder.
  • The diversity in germplasm will affect the crop breeding.
  • It will be converted into large desert.
Identify the incorrect statement among the following statements on the effects of deforestation.
  • It destroys the natural habitat of wild animals.
  • It alters the local weather patterns.
  • It speeds up nutrient recycling.
  • It leads to soil erosion.
Choose the wrong pair
  • Salvodora - Desert
  • Cenchrus - Savanna
  • Ables - Coniferous forest
  • Quercus - Broad leaf forest
  • Tectona - Temperate forest
Consider the following statements (A-D) about organic farming

(A) Utilizes genetically modified crops like Bt cotton.
(B) Uses only naturally produced inputs like compost.
(C) It does not use pesticides and urea.

(D) Produces vegetables rich in vitamins and minerals.

Which of the above statements are correct?
  • (B) and (C) only
  • (A) and (B) only
  • (B), (C), and (D)
  • (C) and (D) only
In 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 darns has gone up
  • There has been increased deforestation in the catchment areas
  • Increased areas of land is being self cultivated
What is the main cause for the extinction of some species in tropical forest?
  • Deforestation
  • Afforestation
  • Pollution
  • Soil erosion
Recurrence of floods in the plains of North India is due to excessive
  • Siltation of dams
  • Rainfall
  • Agriculture
  • Deforestation in catchment area
Concentration of insecticide in the animals of a species is known as ____
  • Eutrophication
  • Bioconcentration
  • Bioindicator
  • None of the above
Limit of BOD prescribed by Central Pollution Control Board for the discharge of industrial and municipal waste waters into natural surface waters, is -
  • < 3.0 ppm
  • <10 ppm
  • < 100 ppm
  • < 30 ppm
Ozone is deadly poisonous, still it performs an essential function.
  • True
  • False
Relative Biological Effectiveness (RBE) usually refers to the damages caused by
  • High temperature
  • Pollution
  • Radiation
  • Low temperature

Assertion :UV - rays are carcinogenic in nature.

Reason : UV - rays rupture DNA strands and induce mutations to cause cancers.
  • If both assertion and reason are true and the reason is the correct explanation of the assertion.
  • If both assertion and reason are true but reason is not the correct explanation of the assertion.
  • If assertion is true but reason is false.
  • If the assertion and reason both are false.
  • If assertion is false but reason is true.
Solid waste serve as useful resource for providing energy for our industries.
  • True
  • False
  • Nihter
  • Either
Many wild animals have either become extinct or are endangered mainly due to 
  • Scarcity of food
  • Over crowding
  • Hunting
  • Deforestation
Match column -I with column-II and select the correct answer using the codes given below :
           Column-I                                Column -II
(A) Global warming                         (p) Eutrophication
(B) Algal bloom                               (q) CO, CO$$_{2}$$
(C) Nitrogen fixation                       (r) Rhizobium
(D) Pseudomonas                            (s) Fossil Fuel
(E) Non-renewable resource           (t) Denitrification
  • (A)- p, (B)- q, (C)- r, (D)- t, (E)- s
  • (A)- q, (B)- p, (C)- r, (D)- t, (E)- s
  • (A)- q, (B)- p, (C)- r, (D)- s, (E)- s
  • (A)- q, (B)- p, (C)- s, (D)- r, (E)- t
A successful forest conservation strategy should involve
  • Protection of animals at the highest trophic level
  • Protection of only sonsumers
  • Protection of only herbivores
  • Comprehensive programme to protect all the physical and biological components
Ozone depletion is occurring due to 
  • PCB
  • CO
  • PAN
  • None of the above
Which one of the following is responsible for causing skin cancer and mutation?
  • Ozone depletion
  • Smog formation
  • Snowfall
  • Smoke from aeroplane
Radioactive substances can cause
  • Cancer
  • Malaria
  • Dysentry
  • Common cold
The presence of ozone in the atmosphere of earth 
  • Hinders higher rate of photosynthesis
  • Has been responsible for increasing the average global temperature in the recent past
  • Helps in checking the ultra violet rays to earth
  • Is advantageous, since it supplies oxygen for people travelling in jets
If the river water is polluted with domestic sewage and garbage, it leads to the depletion of 
  • CO$$_2$$
  • CO
  • O$$_2$$
  • All of the above
The major pollutants to deplete ozone are
  • Chlorofluorocarbons
  • Nitrogen oxides
  • Hydrocarbons
  • All of the above
If BOD of river is high, it means that the river 
  • Is not polluted
  • Is very polluted
  • Does not have green plants
  • Get least amount of light
The ozone layer  'ozonosphere' occurs in
  • Thermosphere
  • Troposphere
  • Stratosphere
  • Heterosphere
'Biological Oxygen Demand' (BOD) is a measure of
  • Industrial wastes poured into water bodies
  • Extent to which water is polluted with organic compounds
  • Amount of carbon monoxide inseparably combined with haemoglobin
  • Amount of oxygen needed by green plants during night
Measuring 'Biochemical Oxygen Demand' (BOD) is a method used for  
  • Estimating the amount of organic matter in sewage water.
  • Measuring the activity of Saccharomyces cervisae in producing curd on a commercial scale.
  • Working out the efficiency of RBCs, about their capacity to carry oxygen.
  • Working out the efficiency of oil driven automobile engines.
Supersonic jets cause pollution by thinning of
  • O$$_3$$ layer
  • SO$$_2$$ layer
  • O$$_2$$ layer
  • CO$$_2$$ layer
Catalytic converter is involved in the control of 
  • Air pollution
  • Radioactive pollution
  • Sewage and chemical from industry
  • Nuclear pollution
Which one of the following is the correct percentage of the two (out of the total of 4) green house gases that contribute to the total global warming?
  • CFCs 14%, Methane 20%
  • CFCs 20%, Methane 14%
  • N$$_2$$O 6%, CO$$_2$$ 86%
  • Methane 20%, N$$_2$$O 18%
The reason for global warming is 
  • Long wavelength radiation are absorbed by the atmosphere
  • Short wavelength radiation are absorbed by the atmosphere
  • Atmosphere traps radiations to increase the temperature
  • UV and infra red radiations
Global warming can be controlled by 
  • Reducing reforestation, increasing the use of fossil fuel
  • Increasing deforestation, slowing down the growth of human population
  • Increasing deforestation, reducing efficiency of energy usage
  • Reducing deforestation, cutting down use of fossil fuel
The worst enemy of ozone is
  • Liquid NH$$_3$$
  • SO$$_2$$
  • CH$$_4$$
  • CFCs
Which method is most effective in controlling floods?
  • Digging deep canals
  • Reforestation
  • Deforestation
  • Constructing dams
Ozone layer of upper atmosphere is being destroyed by 
  • Sulphurdioxide
  • Carbondioxide
  • Chlorofluorocarbon
  • Smog
BOD is
  • The-amount of $$O_2$$ utilised by organisms in water
  • The amount of $$O_2 $$ utilised by micro organisms for decomposition
  • The total amount of $$O_2 $$ present in water
  • All of the above
The major source of BOD in the river Ganga is 
  • Leaf litter
  • Fishes
  • Human waste
  • Aquatic plants
Increase in BOD of water reservoir is due to
  • Algae
  • Soil
  • Moss
  • Waste product
'Biological Oxygen Demand' (BOD) is a measure of 
  • Industrial wastes poured into water bodies.
  • Extent to which water is polluted with organic compounds.
  • Amount of carbon monooxide inseparably combined with haemoglobin.
  • Amount of oxygen needed by green plants during night.
Which of the following is a correct statement?
  • Biogas contains 55% of nitrogen.
  • Producer gas contains 33% of carbon monoxide.
  • CO$$_2$$ is the major constituent in biogas and producer gas.
  • None of the above.
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