CBSE Class 12 Biology Ecosystem Question Bank

Read and download the CBSE Class 12 Biology Ecosystem Question Bank. Designed for 2025-26, this advanced study material provides Class 12 Biology students with detailed revision notes, sure-shot questions, and detailed answers. Prepared by expert teachers and they follow the latest CBSE, NCERT, and KVS guidelines to ensure you get best scores.

Advanced Study Material for Class 12 Biology Chapter 12 Ecosystem

To achieve a high score in Biology, students must go beyond standard textbooks. This Class 12 Chapter 12 Ecosystem study material includes conceptual summaries and solved practice questions to improve you understanding.

Class 12 Biology Chapter 12 Ecosystem Notes and Questions

 

CBSE Class 12 Biology Ecosystem Question Bank. There are many more useful educational material which the students can download in pdf format and use them for studies. Study material like concept maps, important and sure shot question banks, quick to learn flash cards, flow charts, mind maps, teacher notes, important formulas, past examinations question bank, important concepts taught by teachers. Students can download these useful educational material free and use them to get better marks in examinations.  Also refer to other worksheets for the same chapter and other subjects too. Use them for better understanding of the subjects. 

ECOSYSTEM
1. How is a food web formed? 
2. What is stratification in a forest?
3. Define standing crop? How is it measured?
4. What is the importance of humus? 
5. Why is secondary succession faster than primary succession?
6. Name the pioneers and climax of primary succession in water and on rocks. 
7. As succession proceeds the type and number of animals and decomposers also change.
8. Define ecological succession.What is sere 
9. What characteristic features are seen in Ecological succession? 
10. Why is there a restriction on trophic levels in a grazing food chain? Is there such a limitation in the detritus food chain? Explain. 
11. Schematically show the flow of energy in a grazing food chain from the sun. 
12. Justify the statement succession and evolution would have been parallel processes at that time when life started on earth. 
13. In general all pyramids are upright. Explain. What are the exceptions to this generalization? 
14. What are the limitations of ecological pyramids? 
15. What are the producers in grass land and oceans .How is GPP different from NPP? Why is the productivity in oceans lesser than on land?
16. Why is it reasonable to think that biodiversity should carry a hefty price tag? Justify. 
17. a, Why are Carbon and Phophorus essential to living organisms?
a. b, What are the natural reservoirs of these elements and in what form?
b. c, Give the important differences between the two cycles in nature ? 
18. With a flow chart explain the process of decomposition .What factors affect this process? work as a unit to perform the function? 
20. Humans do a disservice to nature by creating a desert from a forest. Comment and say why should it be a cause of concern?
 ECOSYSTEM
(QUESTION BANK)
ANSWER KEY
1 Interconnecting foodchains/one organism in different trophic levels 
2 The vertical levels of trees in a forest 
3 The mass of living matter at a given time measure of biomass ,dry weight of living matter at a given time
4 The colloidal matter resistant to microbial action ,reservoir of nutrients,breaks down slowly 
5 Soil already formed,spores,seeds remnants of vegetation
6 Phytoplanktons and forest,lichens and forest 
7 Vegetational changes, affect food and shelter for various types of animals 
8 Gradual fairly predictable change, in the species composition of a given area.The entire  sequence of communities that change in a given area during the succession
9 There is increase in diversity,species increase and increase in number,increase in biomass 
10 Energy decreases with successive levels. 10% only transferred to next level.
11 Sun----1%------- plants----2-10%-------herbivores------10%------carnivore 
12 Succession starts from the pioneer species giving way to seral communities before establishing the climax.Evolution also involves change of environmental factors followed by change in the communities containing fittest species
13 The producers are the most ,in terms of energy,biomass and number and subsequent levels are fewer in number,energy and Biomass .Energy decreases with successive
levels, The pyramid of Biomass in the oceans and pyramid of number in the case of a fruiting tree supporting hundreds of consumers ,the pyramids can be inverted.
14 Decomposers are not taken into account,two trophic levels may be taken up by the same species which is not considered,a food wb is not accomodated
15 Grass,phytoplanktons,GPP is the rate of Biomass production /g/yr whereas NPP is the rate of Biomass converted into plant matter and available for the consumers
(NPP=GPP-Respiration),Oceans have less solar energy available compared to land hence productivity is lower.
16 Ecosystem services include 1) maintaining soil 2) regulating rainfall 3) preventing erosion of soil,4) pollination 5)providing materials of medicinal,food and other values
17 Carbon part of all organic compounds ,Phosphorus for ATP,DNA etc Gaseous-Reservoir in atmosphere,Nitrogen cycle b)Sedimentary-Soil,eg-phosphorus. No gaseous component in phosphorus and reservoirs of the two are atmosphere and sediments respectively
18 Breakdown of complexorganicmatterbydecomposers.a)Process-i)fragmentation ii)leaching iii)catabolism.Humificationandmineralization–humificationleadsto accumulationofdarkcoloursubstancecalledhumus.Mineralisationresultinreleaseof inorgranic substances
a)climaticfactor– i)tempii)soilb)chemicalqualityofdetritus.Highertempandmoist condition – high rate of decomposition.Drysoil ,High temp–Lowrate
19 Productivity-producers,nutrient cycling and energy flow through the food chains-GFC & DFC,decomposition by the detritivores and decomposers
20 Ecosytem services include regulating the climate,hence livelihood and food of animals and people. Conversion of range land fedcropland, rainorirrigated cropland to desert like and,withadropinagriculturalproductivityof10%ormore.Itisusuallycausedbyacombination ofovergrazing,soilerosion,prolongeddrought,and climatechange. The soil becomes unsuitable for crops and vegetation food would also become scarce besides water and oxygen.
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CBSE Class 12 Biology Chapter 12 Ecosystem Study Material

Students can find all the important study material for Chapter 12 Ecosystem on this page. This collection includes detailed notes, Mind Maps for quick revision, and Sure Shot Questions that will come in your CBSE exams. This material has been strictly prepared on the latest 2026 syllabus for Class 12 Biology. Our expert teachers always suggest you to use these tools daily to make your learning easier and faster.

Chapter 12 Ecosystem Expert Notes & Solved Exam Questions

Our teachers have used the latest official NCERT book for Class 12 Biology to prepare these study material. We have included previous year examination questions and also step-by-step solutions to help you understand the marking scheme too. After reading the above chapter notes and solved questions also solve the practice problems and then compare your work with our NCERT solutions for Class 12 Biology.

Complete Revision for Biology

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