Class 12 Biology — Chapter 12: Ecosystem
90 practice questions · 30 Easy · 30 Medium · 30 Hard
Practise Class 12 Biology Chapter 12, "Ecosystem", with 90 NCERT-aligned multiple-choice questions. The set is split into 30 Easy, 30 Medium and 30 Hard questions, so you can warm up on the fundamentals and then push into the exam-level problems that separate top scorers in CBSE Board exams and NEET UG.
"Ecosystem" is one of the chapters where diagram-based recall, terminology and NCERT line-by-line accuracy really pays off. Each MCQ on this chapter is timed and uses exam-grade marking (+2 correct, −1 wrong, 0 skipped), training the same accuracy-under-pressure that real papers demand. Every question carries a short explanation, so a wrong answer becomes a quick lesson rather than a dead end — the fastest way to close gaps before a test.
Use this chapter as targeted revision: attempt the Easy set first to confirm your basics on Ecosystem, then move to Medium and Hard to test application and problem-solving. Your accuracy, streaks and XP save automatically, and the chapter feeds into your overall Class 12 Biology mastery score. A few sample questions are shown below; sign in free to practise all 90.
Key concepts: Ecosystem (Class 12 Biology)
This chapter covers ecosystem structure and function — productivity, decomposition, energy flow, food chains/webs, ecological pyramids and nutrient cycling.
- Ecosystem structure
- Biotic (producers, consumers, decomposers) and abiotic components interacting as a functional unit.
- Productivity
- Gross primary productivity (GPP) is total energy fixed; net primary productivity (NPP) = GPP − respiration, available to consumers.
- Energy flow
- Unidirectional, following the 10% law — only ~10% of energy passes to the next trophic level.
- Ecological pyramids
- Pyramids of number, biomass and energy; the energy pyramid is always upright.
- Nutrient cycling
- Biogeochemical cycles (carbon, phosphorus) recycle nutrients; decomposers release nutrients back to the environment.
Key formulas — Ecosystem
💡 Exam tips for Ecosystem
- The pyramid of energy is ALWAYS upright; pyramids of number/biomass can be inverted (e.g. a tree ecosystem).
- Energy flow is one-way (10% law); nutrients, by contrast, are recycled.
Sample questions
Producers in an ecosystem:
Convert solar energy via photosynthesis.
Nitrogen fixation by:
Converts N₂ to ammonia.
Net Primary Productivity (NPP) =
Available to consumers.
Ecosystem — FAQs
What are the key concepts in Class 12 Biology Ecosystem?+
This chapter covers ecosystem structure and function — productivity, decomposition, energy flow, food chains/webs, ecological pyramids and nutrient cycling. Key ideas include Ecosystem structure, Productivity, Energy flow, Ecological pyramids, Nutrient cycling.
What does Class 12 Biology Chapter 12 (Ecosystem) cover on XamBaaz?+
It covers 90 NCERT-aligned MCQs on "Ecosystem" — 30 Easy, 30 Medium and 30 Hard — each with a timed quiz and an instant explanation, suitable for CBSE Board exams and NEET UG.
Are these "Ecosystem" questions free to practise?+
Yes — sign in with Google to practise "Ecosystem" free. Full unlimited access is ₹999/year (limited-time launch price), with no per-chapter charges.
How should I revise "Ecosystem" for the exam?+
Start with the Easy quiz to confirm your fundamentals, then attempt Medium and Hard for application-level practice. Review each explanation, retry the questions you miss, and track your accuracy on this chapter until it is consistently high.
Practise all 90 questions free
Timed quizzes, instant scoring, streaks and XP. Sign in with Google — no card needed.
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