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Biology · 2025 · 2 marks
CBSE 2025 · Region 2 · Set 2 · Q21
Student to attempt either option (A) or (B). (A) Construct a pyramid of biomass starting with phytoplankton, label its three trophic levels. Is the…
Student to attempt either option (A) or (B).
(A)
Construct a pyramid of biomass starting with phytoplankton, label its three trophic levels. Is the pyramid upright or inverted ? Justify your answer.
OR
(B)
Draw a pyramid of number where a large population of insects feed upon a very big tree. The insects in turn, are eaten by small birds which in turn are fed upon by big birds.
Marking-scheme solution
• Inverted pyramid of biomass
• The Biomass of fishes is much more than that of zooplankton and phytoplankton so the pyramid is inverted.
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CBSE Class 12 Biology past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.