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Environmental Issues Test - 65

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Environmental Issues Test - 65
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Weekly Quiz Competition
  • Question 1
    1 / -0
    Multiple Choice Questions
    BOD in river water
    Solution
    Biochemical Oxygen Demand or BOD is the amount of dissolved oxygen needed by aerobic microbes to break down organic matter present in a particular water sample at a certain temperature over a specified period of time. Value of BOD increases, given that the organic matter content is high in the water sample. Sewage is rich in organic residues thus it increases BOD of river water upon mixing.
    So, the correct answer is option B, increases when sewage gets mixed up with river water.
  • Question 2
    1 / -0
    The enhanced growth of water hyacinth in lakes can be due to
    Solution
    Water hyacinth (Eichhornia crassipes) also known as Bengal terror is waterweed often blamed for choking water bodies and creating problems for aquatic plants and animal due to less availability of oxygen. It mainly grows where organic nutrient is present in large amount. Level of the nutrient increase due to use of pesticide, weedicides, of discharge of sewage into the water bodies. 
    So, the correct option is 'all of the above'.
  • Question 3
    1 / -0
    How are the wild animals affected by cutting of forest?
    Solution

    Seventy percent of the world's plants and animals live in forests and are losing their habitats to deforestation (cutting of forest), Loss of habitat can lead to species extinction. The number of wild animals decreases by cutting of forest because If the trees are gone, birds, reptiles, and insects lose their homes and food sources. That will affect the small mammals, which are a food source for mid- and large-sized mammals. It is a cascade effect that leads to species extinction. So, the correct answer is 'Number decreases'.

  • Question 4
    1 / -0
    Ozone layer depletion may lead to which of the following harmful effects in organisms?
    Solution
    Ozone gas is found in the stratosphere of the atmosphere. The ozone layer protects the earth from the harmful ultraviolet rays emitted from the sun. Ozone layer depletion has many adverse serious environmental effects. It may result in global warming. The ultraviolet radiations exposure leads to skin cancer like malignant melanoma. It also increases the rate of ageing in an individual. It also has harmful effect on the eyes. It may cause cataract. Immune system is also affected by this harmful ultraviolet radiations. Apart from humans, ozone layer depletion affects marine, aquatic and other forms of life as well.
    Thus, the correct answer is 'All of the above.'
  • Question 5
    1 / -0
    Which harmful radiations are absorbed by ozen layer?
    Solution
    • The ozone layer or ozone($$O_3$$) shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet(UV)radiation.
    • Overexposure to UV radiation may cause skin cancer, damage of the eye and the suppression of the immune system.
    • Hence The harmful radiations are absorbed by ozone layer UV.
    • So, the correct answer is 'UV'.
  • Question 6
    1 / -0
    The maximum hole of ozone is found over ______
    Solution
    Ozone-depleting substances are present throughout the stratospheric ozone layer because they are transported great distances by atmospheric air motions. The severe depletion of the Antarctic ozone layer known as the “ozone hole” occurs because of the special atmospheric and chemical conditions that exist there and nowhere else on the globe. The very low winter temperatures in the Antarctic stratosphere cause polar stratospheric clouds (PSCs) to form. Special reactions that occur on PSCs, combined with the relative isolation of polar stratospheric air, allow chlorine and bromine reactions to produce the ozone hole in Antarctic springtime. 
    So, the correct answer is 'Antarctic zone'.
  • Question 7
    1 / -0
    The bio accumulation of pesticides in birds leads to
    Solution
    • Bioaccumulation is the gradual accumulation of substances, such as pesticides, or other chemicals in an organism. This occurs when the absorption of pesticides is faster than its excretion.
    • Adverse effects of bioaccumulation include accumulation of mercury in the brain causes mercury poisoning, DDT, tetraethyllead kills organisms and the accumulation of pesticides in birds causes egg-shell thinning.
    • Hence The bioaccumulation of pesticides in birds leads to Eggshell thinning.
    • So, the correct answer is 'Eggshell thinning',
  • Question 8
    1 / -0
    Wastes may be sealed in concrete-filled drums and discharged to a depth of about 500 m. This specific statement is true for 
    Solution
    Radiation pollutants are the waste materials that release non ionizing radiation.
    UV radiation can be easily blocked by proper clothing and applying sunscreen. Hence UV pollutants don't need such a strong sealing.
    Particle pollutants are present everywhere in the atmosphere and hence can't be sealed. Most of them are not harmful to humans.
    Radioactive pollutants are the waste materials that release ionizing radiation which can be very dangerous to human beings. hence this kind of waste may be sealed and concrete filled drums and discharged to a depth of 500 m.
    So the correct answer is ' Radioactive pollutants'.
  • Question 9
    1 / -0
    BOD of lake becomes high by :-
    Solution
    BOD or biological oxygen demand is the amount of water needed by aerobic organisms to break down the organic substances (waste substances) present in a water body. Detergents reduce the amount of oxygen in a water body. This may result in an increase in the BOD. It may also result in an increase in eutrophication in the water bodies. Vehicles, wind mill, and smoke and ammonia on the other hand act mostly as air pollutants and are responsible for air pollution.
    So, the correct answer is 'Detergents'.
  • Question 10
    1 / -0
    Why ozone is known as 'chemical weed ' ?
    Solution
    Ozone is an inorganic molecule and a light blue gas with a pungent odor that is prevalent in the stratosphere just below the atmosphere of the earth. Without ozone, plants and animals would be receiving so much radiation from the sun that it would be difficult, if not impossible, for life to even survive here. The effects of no ozone to protect these harmful rays would be that all life here on earth would soon burn up, essentially. Although most associated with the atmosphere, ozone is also a powerful oxidant with many industrial and consumer uses. However, it must be used with extreme caution. The high oxidizing potential of ozone causes damage to mucous and respiratory tissues in animals and also damages tissue in plants at extremely high levels. In commercial agriculture, ozone can be used in conjunction with other chemicals and gases as a control for certain noxious weeds or pests.

    So, the correct option is 'Option A', Because it is formed by chemical reactions.
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