CBSE Questions for Class 12 Medical Biology Environmental Issues Quiz 4 - MCQExams.com

BOD is related with 
  • Organic matter
  • Microbes
  • Both A and B
  • None of the above
An effect of deforestation is
  • Desertification
  • Soil erosion and floods
  • Depletion of wildlife
  • All of the above
Ozone-layer is getting depleted because of
  • Excessive use of automobiles
  • Excessive formation of industrial units
  • Excessive use of man made compounds containing both fluorine and chlorine
  • Excessive deforestation.
Reason for elimination of wild life is 
  • Deforestation
  • Forest fire
  • Roods
  • Less rainfall
What minerals are found in the runoff from agricultural land and untreated sewage effluents that are responsible for eutrophication of water bodies?
  • Phosphorous and carbon
  • Nitrogen and phosphorus
  • Potassium and arsenic
  • Iron and manganese
Measurement of water pollution is made by
  • Coliform count
  • Biological oxygen demand
  • pH
  • All of the above
What is B.O.D.?
  • The amount of $$O_2$$ utilised by organisms in water.
  • The amount of $$O_2 $$ utilized by microorganisms for decomposition.
  • The total amount of $$O_2$$ present in water.
  • All of the above.
Temperature variation in Pacific ocean in present time is called as
  • Cyclone effect
  • El Nino effect
  • Green house effect
  • None of the above
Excess of carbon dioxide in the atmosphere leads to 
  • Global warming
  • Ozone depletion
  • Acid rain
  • None of the above
Which of the following does not affect ozone layer ?
  • Cl$$_2$$
  • CH$$_3$$Cl
  • NO
  • CFCl$$_3$$
The destruction of forests for agricultural and commercial reasons has upset the _____________ balances.
  • Ecological
  • Social
  • Environmental
  • Economical 
Inorganic fertilizers are applied each year to fields bordering a lake. The fertilizers run off into the lake and cause the following six changes which together cause high mortality of fishes.
(i) Aerobic bacteria feed on dead plants. 
(ii) Algae reproduce faster.
(iii) Light cannot penetrate the water.
(iv) Oxygen level falls.
(v) Water becomes green.
(vi) Plants under water die.
Which of the following shows the correct order of the changes taking place?
  • (iv) $$\rightarrow$$ (vi) $$\rightarrow$$ (i) $$\rightarrow$$ (ii) $$\rightarrow$$ (v) $$\rightarrow$$ (iii)
  • (ii) $$\rightarrow$$ (v) $$\rightarrow$$ (iii) $$\rightarrow$$ (vi) $$\rightarrow$$ (i) $$\rightarrow$$ (iv)
  • (v) $$\rightarrow$$ (ii) $$\rightarrow$$ (iii) $$\rightarrow$$ (vi) $$\rightarrow$$ (i) $$\rightarrow$$ (iv)
  • (ii) $$\rightarrow$$ (iii) $$\rightarrow$$ (v) $$\rightarrow$$ (iv) $$\rightarrow$$ (vi) $$\rightarrow$$ (i)
Eutrophication means
  • Toxication of water by fertilisers
  • Decrease in the growth of algae
  • Increase in the fertility of the soil
  • All of the above
Farming without the use of chemicals as fertilizers, herbicides, and pesticides is known as organic farming.
  • True
  • False
Chlorofluorocarbons deplete _______ layer.
  • Ozone   
  • Troposphere
  • Ammonium
  • Oxygen
What are the consequences of deforestation?
  • Soil erosion
  • Loss of biodiversity
  • Floods and droughts and climate change due to global warming
  • All of the above
Increasing amount of $$CO_2$$ in environment is causing ________.
  • Green house effect
  • Global warming
  • Ozone layer depletion
  • Both A and B
Which of the following leads to depletion of dissolved oxygen in water bodies resulting in loss of all aquatic life?
  • Eutrophication
  • Deforestation
  • Soil erosion
  • Soil infertility
Which of the following defines the effect of deforestation on the next generation?
  • Global warming
  • Global cooling
  • Both A and B
  • None of the above
Main cause of extinction of species from tropical areas is
  • Afforestation
  • Deforestation
  • Gamma diversity
  • Delta diversity
A water body has high BOD, indicating that water is
  • Being contaminated with sewage
  • Being aerated
  • Receiving minerals
  • Atrophic
Deforestation is the major cause of
  • Transpiration
  • Genetic erosion
  • Desertification of habitat
  • All of the above
Global warming can be controlled by
  • Reducing deforestation, cutting down use of fossil fuel
  • Reducing reforestation, increasing the use of fossil fuel
  • Increasing deforestation, slowing down the growth of human population
  • Increasing deforestation, reducing efficiency of energy usage
Water blooms are formed by
  • Lemna
  • Hydrilla
  • Water hyacinth
  • Planktonic algae
Fertilisers added to fresh water will cause
  • Death of plants
  • Decrease in carbon dioxide content
  • Increase in aquatic animals
  • Eutrophication
Peak concentration of ozone occurs in the atmosphere above a height of
  • 10 km
  • 15 km
  • 17 km
  • 25 km
Which of the following is an example of freon ?
  • $$CCl_2F_2$$
  • $$CCl_4$$
  • $$CHCl_2$$
  • $$CH_2Cl$$
Frequent floods in plains of Northern India is due to
  • Excessive rainfall
  • Siltation of dams
  • Deforestation in catchment areas
  • Agriculture
Deforestation generally decreases 
  • Rainfall
  • Soil erosion
  • Drought
  • Global warming
Presence of CFCs in the atmosphere is responsible for
  • Formation of ozone
  • Production of healthy plants
  • Depletion of ozone layer
  • None of these
BOD of a pond is related to .......... in per unit volume of water.
  • All the plants
  • All the nektons
  • All the microbes
  • All the animals
Ozone layer is disturbed by
  • Large number of factories
  • Supersonic jets
  • Large number of automobiles
  • None of these
At what height over the earth does the ozone layer exist?
  • 200 km
  • 150 km
  • 100 km
  • 25 km
Occurrence of water blooms in a lake indicates
  • Excessive nutrient availability
  • Nutrient defciency
  • Oxygen defciency
  • Absence of herbivores
Which one of following pairs of gases is the major cause of greenhouse effect?
  • $$CO$$ and $$O_3$$
  • $$CO_2$$ and $$CO$$
  • $$CO$$ and $$SO_2$$
  • $$CO_2$$ and $$N_2O$$
Chernobyl nuclear tragedy occurred in
  • April, 1986
  • August 6, 1945
  • August 9, 1945
  • December 3, 1984
Environment is warmed up by
  • Water vapour
  • Methane
  • $$CO_2$$
  • All of the above
Which of the following provides nutrients to the seedlings to grow in forests?
  • Bacteria
  • Fungi
  • Decaying animal dung
  • Beetles and grubs
Radioactive pollution along Kerala coast is due to
  • Zinc
  • Thorium
  • Caesium
  • Plutonium
High BOD values for a river means that river water
  • Have no microbes
  • Have more bacteria
  • Is highly polluted
  • Is highly clean
Through food chain radioactive Sr is deposited in which part of human body? 
  • Muscles
  • Thyroid
  • Kidnies
  • Bones
One of the most dangerous radioactive pollutant is
  • C$$^{14}$$
  • S$$^{35}$$
  • Sr$$^{90}$$
  • P$$^{32}$$
Which of the following damages WBC, bone marrow and lymph nodes?
  • Ca$$^{40}$$
  • I$$^{131}$$
  • Sr$$^{90}$$
  • Caesium
The common refrigerant chlorofluoromethane (Freon) and NO$$_x$$ is a serious pollutant because?
  • It destroys haemoglobin
  • It disrupts O$$_3$$ layer
  • It lowers atmospheric temperature
  • It prevents cloud condensation
BOD is related to
  • Organic pollutants
  • Detergents
  • Putrescibility
  • Inorganic pollutants
C.O.D. stands for
  • Chemical oxygen demand
  • Control of diesel
  • Csiumoxide deposition
  • Cemistry of depositions
In the polluted water, the values of
  • C.O.D. slightly higher than B.O.D.
  • C.O.D. much higher than B.O.D.
  • B.O.D. slightly higher than C.O.D.
  • B.O.D. much higher than C.O.D.
The ultimate environmental hazard or the most outstanding danger for the survival of living beings on this planet is:
  • Radiation hazard or nuclear pollution
  • Glaciation
  • Deforestation
  • Desertification
The automobile emission can be reduced by adding which of the following in the petrol?
  • Barium salts
  • Cadmium salts
  • Cobalt salts
  • Silicon 011
Which of the following does not contributes to greenhouse effect?
  • Carbon dioxide
  • Carbon monoxide
  • Chloro-fluoro carbon and Methane
  • Refrigerant freon
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