Class 12 Biology - KERALA
Ecosystem
The chapter 'Ecosystem' in Class 12 Biology (Kerala SCERT) explores the structural and functional units of nature where living organisms interact with each other and their physical environment. Students will study productivity, decomposition, energy flow through trophic levels, ecological pyramids, and nutrient cycling (carbon and phosphorus). Additionally, the chapter covers ecological succession and ecosystem services. This is a high-scoring unit in the Kerala Board examinations, frequently featuring questions on ecological pyramids, energy flow percentages (10% law), and differences between primary and secondary succession.
Start Learning FreeKey Concepts
Productivity
The rate of biomass production, divided into Gross Primary Productivity (GPP) and Net Primary Productivity (NPP), which is available to consumers.
Decomposition
The breakdown of complex organic matter into inorganic substances through processes like fragmentation, leaching, catabolism, humification, and mineralization.
Energy Flow
The unidirectional movement of energy through trophic levels in an ecosystem, following the 10% law of energy transfer.
Ecological Pyramids
Graphical representations of trophic structure and function, which can be pyramids of number, biomass, or energy.
Ecological Succession
The predictable and progressive change in species composition in a given area over time, leading to a climax community.
Important Formulas
Board Exam Info
In the Kerala (SCERT) Class 12 Biology public examination, this chapter typically carries around 4 to 6 marks. Common question types include short notes on ecological succession, diagrammatic representation of ecological pyramids, differentiating between GPP and NPP, and explaining steps of decomposition.
Frequently Asked Questions
Why is the pyramid of energy always upright?
Because energy is lost as heat at each trophic level during transfer, according to the second law of thermodynamics, making the energy content always highest at the producer level.
What is the difference between primary and secondary ecological succession?
Primary succession occurs on bare, lifeless areas where life has never existed before (e.g., bare rock), while secondary succession occurs in areas where natural life was previously destroyed (e.g., a burnt forest).
What is the 10% law in an ecosystem?
Proposed by Lindeman, it states that only about 10% of the energy is transferred from one trophic level to the next; the rest is lost during respiration and metabolic activities.
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