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Biology · 2022 · 3 marks
CBSE 2022 · Region 1 · Set 1 · Q8
Bio-diversification of life started to occur almost 3 billion years ago. Since then new species have been evolving and then disappearing en masse…
Bio-diversification of life started to occur almost $\displaystyle 3$ billion years ago. Since then new species have been evolving and then disappearing en masse from earth.
(a)
How many episodes of mass extinctions of species have already taken place and which one is in progress in the current era ?
(b)
How is current episode in progress different from the previous episodes and why ? Explain.
Marking-scheme solution
(a)
Five extinctions have already occurred
sixth is in progress
(b)
Sixth extinction is much faster / sixth extinction is $\displaystyle 100$ to $\displaystyle 1000$ times faster
Human activities like industrialisation, loss of habitat, over exploitation,land reforms.
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CBSE Class 12 Biology past-paper question from the 2022 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.