Introduction
Chapter 13 Biodiversity and Conservation is a core ecology chapter in Class 12 Biology that explains the immense variety of life forms present on Earth and highlights the urgent need to conserve this biological wealth. Biodiversity is not limited to counting species alone; it also reflects genetic variation within species, diversity of ecosystems, evolutionary history, and ecological stability. A biologically rich planet is essential for sustaining natural processes that support life, including food production, climate regulation, and nutrient cycling.
From a JEE perspective, this chapter is highly conceptual and NCERT-driven. Questions are often straightforward in wording but demand clarity of definitions, logical understanding of patterns, and precise knowledge of causes and conservation strategies. At Deeksha Vedantu, this chapter is taught with a strong emphasis on conceptual linking, helping students understand why biodiversity varies across regions and how conservation strategies are designed to address biodiversity loss. This approach prepares students well for assertion–reason, match-the-following, and statement-based questions frequently asked in JEE Main.
What Is Biodiversity?
Biodiversity refers to the totality of biological variation found at different levels of organisation, including genes, species, and ecosystems. It represents the collective variety of life forms present on Earth and forms the foundation of ecosystem functioning and evolutionary processes.
Biodiversity is commonly studied at three hierarchical levels:
- Genetic diversity
- Species diversity
- Ecosystem diversity
Clear understanding of these levels is essential because JEE questions often test precise definitions and the ability to differentiate between them.
Genetic Diversity
Genetic diversity refers to variation in genes within a species. This variation may exist between individuals of the same population or among different populations of the same species. Genetic diversity enables populations to adapt to changing environmental conditions and provides resistance against diseases and environmental stresses.
For example, different varieties of crops, strains of microorganisms, or breeds of domesticated animals represent genetic diversity within a species. When genetic diversity is reduced, populations become more vulnerable to epidemics, environmental changes, and extinction. JEE questions may indirectly test the importance of genetic diversity in long-term species survival.
Species Diversity
Species diversity refers to the variety of species present in a particular region. It includes two components:
- Species richness, which is the number of species present
- Species evenness, which refers to the relative abundance of different species
Regions with high species diversity generally show greater ecosystem stability and productivity. Species diversity is one of the most frequently tested concepts in this chapter, especially in relation to biodiversity patterns, latitudinal gradients, and conservation priorities.
Ecosystem Diversity
Ecosystem diversity refers to the variety of ecosystems found within a geographical region. Forests, grasslands, deserts, wetlands, freshwater ecosystems, and marine ecosystems together contribute to ecosystem diversity.
Higher ecosystem diversity usually supports higher species diversity because a greater variety of habitats and ecological niches are available. Ecosystem diversity also increases resilience against environmental disturbances, an idea that is often linked conceptually with conservation in JEE questions.
Patterns of Biodiversity
Biodiversity is not evenly distributed across the Earth. NCERT highlights specific global patterns that explain why some regions are richer in species than others.
Latitudinal Gradients in Biodiversity
One of the most prominent patterns is the latitudinal gradient in biodiversity. Species diversity is highest in tropical regions and gradually decreases towards temperate and polar regions.
Several factors contribute to higher biodiversity in the tropics:
- Relatively stable and predictable climatic conditions
- Higher solar energy input leading to greater productivity
- Longer evolutionary time without major disturbances
JEE questions frequently test the reasoning behind this pattern rather than asking for simple recall.
Species–Area Relationship
Another important pattern is the species–area relationship, which states that species richness increases with an increase in the area explored. This relationship is represented by a rectangular hyperbola when species number is plotted against area.
When plotted on a logarithmic scale, the relationship becomes linear. Larger areas support more species because they provide a wider range of habitats, greater resource availability, and reduced chances of extinction. This relationship is sometimes tested in JEE through conceptual or mathematical reasoning questions.
Importance of Biodiversity
Biodiversity is essential for maintaining ecosystem stability, resilience, and productivity. Loss of biodiversity can disrupt ecological balance and threaten the survival of many species, including humans.
Major reasons for conserving biodiversity include:
- Maintenance of ecological stability and ecosystem services
- Economic benefits such as food, medicine, fuel, and raw materials
- Aesthetic, cultural, and recreational value
- Ethical responsibility to protect life forms with whom humans share the planet
NCERT emphasises that biodiversity is a priceless natural resource, and its loss can have irreversible consequences.
Loss of Biodiversity
Human activities have greatly accelerated the rate of biodiversity loss. The current rate of species extinction is estimated to be much higher than the natural background extinction rate.
Causes of Biodiversity Loss
NCERT identifies four major causes of biodiversity loss, collectively referred to as the “Evil Quartet”:
- Habitat loss and fragmentation
- Over-exploitation of natural resources
- Invasion by alien species
- Co-extinctions
Habitat loss and fragmentation is the most significant cause, leading to shrinking habitats, isolated populations, and increased risk of extinction. Over-exploitation reduces population sizes, while alien species may outcompete native species. Co-extinctions occur when the extinction of one species leads to the loss of another dependent species. These causes are frequently tested in JEE through direct and indirect questions.
Biodiversity Conservation
Conservation of biodiversity aims to protect ecosystems, preserve species, and ensure sustainable use of biological resources.
Conservation strategies are broadly classified into:
- In situ conservation
- Ex situ conservation
In Situ Conservation
In situ conservation involves conserving species in their natural habitats. This approach protects entire ecosystems and maintains natural evolutionary processes.
Examples of in situ conservation include:
- National parks
- Wildlife sanctuaries
- Biosphere reserves
Biodiversity hotspots are regions with very high species richness and a high degree of endemism. Conservation of hotspots is given priority because protecting small areas can conserve a large number of species.
Ex Situ Conservation
Ex situ conservation involves protecting species outside their natural habitats. This method is used when species face immediate threats in the wild.
Examples include:
- Zoological parks
- Botanical gardens
- Seed banks
- Cryopreservation
Ex situ conservation acts as a supplementary strategy to in situ conservation. At Deeksha Vedantu, students are trained to clearly differentiate between these two methods, as this comparison is commonly tested in JEE.
Biodiversity and Conservation for JEE Preparation
Conceptual Focus
JEE questions from this chapter mainly focus on:
- Definitions and levels of biodiversity
- Global patterns of biodiversity
- Species–area relationship
- Causes of biodiversity loss
- Conservation strategies
Clear understanding of NCERT terminology and logical connections between concepts is essential for scoring well.
Scoring Potential
Biodiversity and Conservation is considered a high-scoring chapter because most questions are direct, NCERT-based, and concept-oriented. With systematic revision and conceptual clarity, as emphasised at Deeksha Vedantu, students can confidently secure full marks from this chapter.
FAQs
Q1. What is biodiversity?
Biodiversity refers to the variety of genes, species, and ecosystems present in a region.
Q2. What are the three levels of biodiversity?
The three levels of biodiversity are genetic diversity, species diversity, and ecosystem diversity.
Q3. Why is biodiversity highest in tropical regions?
Tropical regions have stable climates, higher productivity, and longer evolutionary history, which support greater species diversity.
Q4. What is the evil quartet?
The evil quartet refers to habitat loss, over-exploitation, invasion of alien species, and co-extinctions that cause biodiversity loss.
Q5. What is the difference between in situ and ex situ conservation?
In situ conservation protects species in their natural habitats, while ex situ conservation protects species outside their natural habitats.
Conclusion
Chapter 13 Biodiversity and Conservation highlights the richness of life on Earth and the urgent need to conserve it. For JEE aspirants, the focus should be on thoroughly understanding biodiversity levels, global patterns, causes of biodiversity loss, and conservation strategies exactly as presented in NCERT. A concept-driven preparation approach, similar to the one followed at Deeksha Vedantu, helps students build accuracy, confidence, and strong ecological reasoning skills required for competitive examinations.
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