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Science · 2022 · 3 marks
CBSE 2022 · Region 2 · Set 1 · Q13
(a) We do not clean ponds or lakes, but an aquarium needs to be cleaned regularly. Why? (b) Why is ozone layer getting depleted at the higher levels…
(a)
We do not clean ponds or lakes, but an aquarium needs to be cleaned regularly. Why ?
(b)
Why is ozone layer getting depleted at the higher levels of the atmosphere ? Mention one harmful effect caused by its depletion.
Marking-scheme solution
(a)
A pond is a natural ecosystem having its own cleaning system in the form of decomposers whereas an aquarium is a man-made or artificial ecosystem having no decomposers.
(b)
It is due to release of chlorofluorocarbons (CFCs) in the atmosphere.
The harmful UV radiations would reach earth and cause damage to different life forms on the earth / cause skin cancer in human beings.
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