Class 12 Biology - WEST-BENGAL
Biodiversity and Conservation
The chapter 'Biodiversity and Conservation' in Class 12 Biology under WBBSE explores the immense variety of life on Earth at genetic, species, and ecosystem levels. Students will learn about patterns of biodiversity, latitudinal gradients, and the species-area relationship. The chapter highlights the alarming rates of biodiversity loss driven by habitat destruction, overexploitation, alien species invasions, and co-extinctions. It emphasizes the urgent need for conservation through in-situ methods (national parks, wildlife sanctuaries, biosphere reserves) and ex-situ methods (zoos, botanical gardens, cryopreservation), along with significant global initiatives like the Earth Summit.
Start Learning FreeKey Concepts
Levels of Biodiversity
Biodiversity exists at three main levels: Genetic diversity (variation within species), Species diversity (variety of species within a region), and Ecological diversity (variety of ecosystems in a region).
Latitudinal Gradients
Species diversity generally decreases as we move away from the equator towards the poles, making tropical regions hotspots of high biodiversity.
Species-Area Relationship
Alexander von Humboldt observed that within a region, species richness increases with increasing explored area, represented logarithmically as log S = log C + Z log A.
Evil Quartet
The four major causes of biodiversity loss are Habitat loss and fragmentation, Over-exploitation, Alien species invasions, and Co-extinctions.
In-situ and Ex-situ Conservation
In-situ conservation protects organisms in their natural habitats (e.g., sanctuaries), whereas ex-situ conservation protects them outside their natural habitats (e.g., botanical gardens, gene banks).
Important Formulas
Board Exam Info
In the West Bengal Council of Higher Secondary Education (WBBSE) Class 12 Biology examination, this chapter typically carries around 4 to 6 marks. Questions frequently include short answer type questions (SAQ) on conservation strategies, differentiating between in-situ and ex-situ conservation, and descriptive questions on the 'Evil Quartet' or reasons for high tropical biodiversity.
Frequently Asked Questions
In-situ conservation involves protecting endangered species in their natural habitat (e.g., National Parks), while ex-situ conservation involves protecting them away from their natural habitat in specialized facilities (e.g., Zoos, Cryopreservation).
What does 'Z' represent in the Species-Area relationship equation?
Z represents the slope of the regression line (regression coefficient). Its value generally lies between 0.1 and 0.2, regardless of the taxonomic group or region.
Why are biodiversity hotspots important?
Biodiversity hotspots are regions with very high levels of species richness and high endemism (species found nowhere else), which are facing constant threat of habitat destruction and thus require urgent priority conservation.
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