Ecosystem — Class 12 Biology NCERT Solutions (Free)

Free step-by-step NCERT solutions for Class 12 Biology chapter "Ecosystem" — 8 important questions with detailed answers for CBSE board exam preparation.

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TL;DR: Free step-by-step NCERT solutions for Class 12 Biology chapter "Ecosystem" — 8 important questions with detailed answers for CBSE board exam preparati…

Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated Jul 23, 2026

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Key Questions Covered:

Define an ecosystem. What are its main components?
Explain energy flow in ecosystems. What is the 10% law?
Describe nutrient cycling. Explain the carbon cycle and nitrogen cycle.
What are food chains and food webs? Explain the concept of trophic levels.
Define ecological pyramid. Explain pyramids of numbers, biomass, and energy.
What is ecological efficiency? Calculate energy available at different trophi…
+ 2 more questions in the full chapter

Solutions Summary:

Question	Status
Define an ecosystem. What are its main components?	✓ Solved
Explain energy flow in ecosystems. What is the 10% law?	✓ Solved
Describe nutrient cycling. Explain the carbon cycle and n…	✓ Solved
What are food chains and food webs? Explain the concept o…	✓ Solved
Define ecological pyramid. Explain pyramids of numbers, b…	✓ Solved
What is ecological efficiency? Calculate energy available…	✓ Solved

Showing 6 of 8 questions

Q1: Define an ecosystem. What are its main components?

An ecosystem is a functional unit of nature comprising all living organisms (biotic components) and their physical environment (abiotic components) interacting together through energy flow and nutrient cycling. MAIN COMPONENTS: BIOTIC COMPONENTS: 1. Producers (Autotrophs) - Green plants, photosynthetic bacteria, algae - Convert solar energy into chemical energy (food) - Form base of food chains 2. Consumers (Heterotrophs) - Primary consumers: Herbivores eating plants - Secondar...

Q2: Explain energy flow in ecosystems. What is the 10% law?

Energy flow is the movement of energy through an ecosystem from sun through organisms to environment as heat. It is unidirectional and decreases at each level.

Q3: Describe nutrient cycling. Explain the carbon cycle and nitrogen cycle.

Nutrient cycling (biogeochemical cycles) involves circular movement of nutrients between biotic and abiotic components of ecosystem. Nutrients are recycled indefinitely.

Q4: What are food chains and food webs? Explain the concept of trophic levels.

Food chains and webs show transfer of energy and nutrients through different organisms in ecosystem.

Q5: Define ecological pyramid. Explain pyramids of numbers, biomass, and energy.

Ecological pyramids are graphical representations showing quantitative relationships between organisms at different trophic levels.

Q6: What is ecological efficiency? Calculate energy available at different trophic levels.

Ecological efficiency refers to percentage of energy transferred from one trophic level to next, typically 10%.

Showing 6 of 8 questions. Visit the full page for complete solutions.

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