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Environmental Issues — BIOLOGY STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYEnvironmental Issues2 Marks
Question
Answer the following:
  1. What depletes ozone in the stratosphere? How does this affect human life?
  2. What is El Nino effect? Explain how it accounts for biodiversity loss.
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Answer

  1. Ozone in the stratosphere is depleted by CFCS, i.e. chlorofluorocarbons, released primarily from refrigerators and other industrial emissions. This affects the human life as it leads to more exposure of UV radiation, which is considered to be harmful for health.
  2. Effects of UV Rays:
    1. Damage to DNA and leads to mutation.
    2. Damage to the skin cells.
    3. Ageing of the skin.
    4. Various types of cancers.
  3. El Nino is abnormal warming of surface ocean water in the Eastern Pacific Ocean. During El Nino, there is movement of warm water to East which causes bleaching and death of coral reefs. It changes the route of migration of birds, fishes and whales thereby increasing the risk for them. It is also known to be responsible for sudden changes in rainfall pattern and drought. All this makes El Nino, a factor for biodiversity loss.

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