Class 12 Biology - HARYANA
Ecosystem
The Ecosystem chapter in Class 12 Biology explores the structural and functional units of nature where living organisms interact with each other and their physical environment. Important topics covered for the Haryana Board (BSEH) examinations include ecosystem productivity, decomposition, energy flow through trophic levels, ecological pyramids, and nutrient cycling (carbon and phosphorus). You will also learn about ecological succession and ecosystem services. This chapter is vital for board exams as it tests conceptual understanding through direct questions, numerical problems on energy transfer, and diagram-based questions on ecological pyramids and nutrient cycles.
Start Learning FreeKey Concepts
Productivity
The rate of biomass production, divided into Gross Primary Productivity (GPP) and Net Primary Productivity (NPP) after plant respiration losses.
Decomposition
The breakdown of complex organic matter into inorganic substances through steps like fragmentation, leaching, catabolism, humification, and mineralization.
Energy Flow
The unidirectional movement of energy through trophic levels in a food chain, governed by 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 sequential change in the species composition of a given area over time, leading to a climax community.
Important Formulas
Board Exam Info
In the Haryana Board (BSEH) Class 12 Biology examination, this chapter typically carries around 4-6 marks. Common question types include short-answer questions on decomposition steps, differentiation between GPP and NPP, drawing and explaining ecological pyramids, and numerical or conceptual problems based on energy flow in food chains.
Frequently Asked Questions
Energy flow is unidirectional because energy captured by autotrophs from the sun does not go back to the sun, and energy lost as heat at each trophic level cannot be reused by organisms.
Energy flow is unidirectional because energy captured by autotrophs from the sun does not go back to the sun, and energy lost as heat at each trophic level cannot be reused by organisms.
Can an ecological pyramid be inverted?
Yes, certain ecological pyramids can be inverted. For example, the pyramid of biomass in a aquatic ecosystem is inverted because the biomass of phytoplankton is much lower than that of zooplankton at any given time.
What is the difference between primary and secondary succession?
Primary succession starts in areas where no living organisms ever existed (like bare rock), while secondary succession begins in areas that have lost all previous life (like a burnt forest), making secondary succession much faster.
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