CBSE 2026 · Region 3 · Set 1 · Q14 · 1 mark
Assertion (A): Ecosystems require a constant supply of energy to synthesize the molecules they require.
Reason (R) : This is to counteract the universal tendency towards increasing disorderliness as per Second Law of Thermodynamics.
Official answer
From CBSE’s own marking scheme for this paper.
(A)
Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
EcosystemEnergy FlowUnderstandassertion_reasonmedium
More from Ecosystem
- Observe the contents 1, 2, 3 and 4 of soil samples I, II and III shown in the graph. If the temperature and…2026 · asked 3×
- Below is shown a pond that represents a self-sustaining natural ecosystem with both biotic and abiotic…2026 · asked 3×
- Name the type of food chains responsible for the flow of larger fraction of energy in an aquatic ecosystem…2025 · asked 3×
- Differentiate between grazing food chain and detritus food chain. OR Explain Brood parasitism with the help…2024 · asked 3×
- Assertion: In terrestrial ecosystem much larger fraction of energy flows through grazing food chain. Reason…2026 · asked 3×
- Write important features of 'humus' formed during the decomposition cycle in a terrestrial ecosystem. OR (i)…2024 · asked 3×
- Assertion: Decomposition process is slower if detritus is rich in lignin and cutin. Reason (R): Decomposition…2023 · asked 3×
- Assertion: Some aquatic ecosystems have inverted biomass pyramids. Reason (R): More energy is required by the…2024 · asked 3×
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.