Class 12 Biology - CBSE
Biodiversity and Conservation
Biodiversity and Conservation explores the immense variety of life on Earth at genetic, species, and ecological levels, and highlights the urgent need to protect these natural resources. For CBSE Class 12 board exams, this chapter is high-scoring and forms a crucial part of the Ecology unit. You will learn about patterns of biodiversity, the alarming rates of extinction due to human activities, and the strategies used for conservation, including in-situ and ex-situ methods. Understanding concepts like the 'Rivet Popper Hypothesis' and species-area relationships is essential for both conceptual clarity and direct application-based questions in your board papers.
Start Learning FreeKey Concepts
Levels of Biodiversity
Biodiversity exists at three hierarchical levels: genetic diversity (variation within a species), species diversity (diversity among species in a given region), and ecological diversity (variety of biological communities and ecosystems).
Latitudinal Gradients in Biodiversity
Biodiversity generally decreases as we move away from the equator towards the poles, making tropical regions hotspots of rich biological wealth due to consistent climates and high solar energy.
Species-Area Relationship
Proposed by Alexander von Humboldt, it states that within a region, species richness increases with the explored area, but only up to a limit, represented mathematically on a logarithmic scale as a straight line.
The Evil Quartet
The four major causes of accelerated biodiversity loss are Habitat loss and fragmentation, Over-exploitation, Alien species invasions, and Co-extinctions.
In-situ vs Ex-situ Conservation
In-situ conservation protects species in their natural habitats (e.g., National Parks, Biosphere Reserves), whereas ex-situ conservation protects endangered species outside their natural habitats in specialized facilities (e.g., zoos, botanical gardens, seed banks).
Important Formulas
Board Exam Info
In the CBSE Class 12 Biology board exam, the Ecology unit typically carries around 14 marks, with Biodiversity and Conservation contributing roughly 3 to 5 marks. Common question types include direct definitions (like hotspots and endemism), numerical or conceptual questions based on the Species-Area relationship graph, and distinguishing between in-situ and ex-situ conservation methods.
Frequently Asked Questions
What is the difference between In-situ and Ex-situ conservation?
In-situ conservation involves protecting endangered plants and animals in their natural habitat (e.g., wildlife sanctuaries), while ex-situ conservation involves protecting them away from their natural habitat in places like botanical gardens, zoos, or gene banks.
Why is the Z value (slope) steeper for larger areas like continents?
For very large areas like entire continents, the species-area relationship has a much steeper slope (Z = 0.6 to 1.2) because different geographical regions within a continent tend to house completely different sets of species, leading to a much faster rate of species accumulation as area increases.
What are Biodiversity Hotspots and how many are there globally?
Biodiversity hotspots are regions with very high levels of species richness and a high degree of endemism (species found nowhere else) that are under constant threat of habitat loss. Globally, there are 36 recognized biodiversity hotspots, of which 3 are in India.
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