CBSE 2026 · Region 1 · Set 1 · Q21 · 2 marks
Given below is a pyramid found in an ecosystem, where each bar represents the standing crop available in the trophic level.(i)Identify the kind of pyramid and with the help of an example explain the conditions where this kind of pyramid is possible in nature.(ii)Write any two limitations of ecological pyramids.In an ecosystem there was loss of biodiversity due to some project in that area.(i)How will biodiversity be affected? ($\displaystyle 2$ points)(ii)List two major causes of loss of biodiversity.
Given below is a pyramid found in an ecosystem, where each bar represents the standing crop available in the trophic level.
(i)
Identify the kind of pyramid and with the help of an example explain the conditions where this kind of pyramid is possible in nature.
(ii)
Write any two limitations of ecological pyramids.
In an ecosystem there was loss of biodiversity due to some project in that area.
(i)
How will biodiversity be affected? ($\displaystyle 2$ points)
(ii)
List two major causes of loss of biodiversity.
Marking-scheme solution
(i)
• Inverted Pyramid of Biomass
• Such pyramids are seen in – Aquatic conditions where a small standing crop of phytoplanktons supports a large standing crop of zooplankton or fish / In terrestrial ecosystem – when a large number of insects are feeding on a single tree / or any other correct example
(ii)
• Ecological pyramids does not take into account the same species belonging to two or more trophic levels.
• It does not accommodate a food web.
• Saprophytes are not given any place in ecological pyramids even though they play a vital role in the ecosystem.
(Any two)
(i)
• Decline in plant production.
• Lowered resistance to environmental perturbations as drought.
• Increased variability in certain ecosystem processes such as water use and pest and disease cycles
• Any other correct point
(Any two points)
(ii)
• Habitat loss and fragmentation.
• Alien species invasion.
• Over exploitation
• Co-extinction
(Any two)
EcosystemEcological PyramidsUnderstandvery_short_answermedium
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CBSE Class 12 Biology past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.