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Biology · 2026 · 3 marks
CBSE 2026 · Region 4 · Set 2 · Q25
(a) What is primary productivity? Why does it vary in different types of ecosystems? (b) Why is the assimilation of energy at the herbivore level…
(a)
What is primary productivity ? Why does it vary in different types of ecosystems ?
(b)
Why is the assimilation of energy at the herbivore level called secondary productivity ?
Marking-scheme solution
(a)
• Primary productivity- The amount of biomass or organic matter produced per
unit area over a time period by the plants during photosynthesis.
• It varies in different ecosystem depending upon–
-The plant species inhabiting a particular area.
-The environmental factors.
Photosynthetic capacity of plants
Availability of nutrients
(b)
Herbivores are the primary consumers the rate of assimilation or formation of new organic matter at the consumer level is secondary productivity.
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CBSE Class 12 Biology past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.