Chapter Overview & Weightage
Biodiversity and Conservation covers biodiversity levels, patterns, loss of biodiversity, conservation strategies, biodiversity hotspots, and endangered species. This is a factual chapter where knowing specific numbers and examples scores direct marks.
This chapter carries 3-4% weightage in NEET with 2-3 questions. Species-area relationship, biodiversity hotspots, and conservation strategy types are the most tested.
Key Concepts You Must Know
Tier 1 (Core)
- Three levels of biodiversity: genetic, species, ecological (ecosystem)
- Species-area relationship: (where = species richness, = area, = slope)
- value: 0.1-0.2 for small areas within a continent; 0.6-1.2 for islands or when studying entire continents
- Loss of biodiversity: habitat destruction, overexploitation, alien species invasion, co-extinction
- Conservation: in-situ (national parks, wildlife sanctuaries, biosphere reserves) vs ex-situ (zoos, botanical gardens, seed banks, cryopreservation)
Tier 2 (Frequently tested)
- Biodiversity hotspots: 36 globally, India has 4 (Western Ghats, Himalayas, Indo-Burma, Sundaland)
- IUCN Red List categories: extinct, endangered, vulnerable, near threatened
- Evil Quartet of biodiversity loss: habitat loss, overexploitation, alien species, co-extinction
- Rivet popper hypothesis (Paul Ehrlich): each species is like a rivet in an airplane — losing too many causes collapse
Tier 3 (Occasionally tested)
- Sacred groves as conservation example
- Convention on Biological Diversity (CBD), Rio Earth Summit
- Biodiversity numbers: ~1.5 million described species, estimated 5-50 million total
Important Formulas
Where:
- = species richness
- = area
- = Y-intercept (varies by taxonomic group)
- = regression coefficient (slope)
Normal Z value: 0.1 to 0.2 (within a region) Steep Z value: 0.6 to 1.2 (when considering very large areas like entire continents)
Interpretation: As area increases, species richness increases — but the relationship is logarithmic (not linear). Doubling the area does NOT double the species count.
| Strategy | Type | Examples |
|---|---|---|
| National Parks | In-situ | Jim Corbett, Kaziranga, Gir |
| Wildlife Sanctuaries | In-situ | Bharatpur, Periyar |
| Biosphere Reserves | In-situ | Nilgiri, Sundarbans, Nanda Devi |
| Zoos | Ex-situ | Delhi Zoo, Mysore Zoo |
| Botanical Gardens | Ex-situ | Royal Botanic Gardens (Kew) |
| Seed Banks | Ex-situ | Svalbard Global Seed Vault |
| Sacred Groves | In-situ (traditional) | Khasi and Jaintia Hills (Meghalaya) |
The value distinction is a classic NEET question: normal ( = 0.1-0.2) vs steep ( = 0.6-1.2). The steep value appears when you consider very large areas (entire continents or oceanic islands). For regions within a continent, is low because species overlap across adjacent habitats.
Solved Previous Year Questions
PYQ 1 — NEET 2024
Problem: In the species-area relationship, the value of Z for frugivorous birds and mammals in tropical forests is approximately:
(A) 0.6-1.2 (B) 0.1-0.2 (C) 2.0-3.0 (D) 0.01-0.02
Solution:
Alexander von Humboldt found that within a region, the value is typically 0.1 to 0.2 regardless of the taxonomic group (plants, birds, mammals). The steeper values (0.6-1.2) occur only when analyzing very large continental or island areas.
Answer: (B) 0.1-0.2
PYQ 2 — NEET 2023
Problem: Which of the following is an ex-situ conservation strategy?
(A) National park (B) Wildlife sanctuary (C) Cryopreservation (D) Biosphere reserve
Solution:
Cryopreservation (preserving gametes, seeds, or embryos at ultra-low temperatures in liquid nitrogen) is an ex-situ strategy — the organisms/genetic material are conserved outside their natural habitat. National parks, wildlife sanctuaries, and biosphere reserves are all in-situ.
Answer: (C) Cryopreservation
PYQ 3 — NEET 2022
Problem: How many biodiversity hotspots are there in India?
(A) 2 (B) 3 (C) 4 (D) 5
Solution:
India has 4 biodiversity hotspots: Western Ghats + Sri Lanka, Himalayas, Indo-Burma, and Sundaland (includes Nicobar Islands). Globally, there are 36 recognized biodiversity hotspots.
A region qualifies as a hotspot if it has high endemism (1500+ endemic plant species) AND has lost 70% or more of its original habitat.
Answer: (C) 4
Difficulty Distribution
| Difficulty | % of Questions | What to Expect |
|---|---|---|
| Easy | 50% | In-situ vs ex-situ, hotspot count, conservation strategy examples |
| Medium | 35% | Species-area relationship, Z value interpretation, evil quartet |
| Hard | 15% | Rivet popper hypothesis application, specific conservation examples |
Expert Strategy
Single session (2-3 hours): This is a compact chapter. Learn the species-area equation and Z values, the 4 Indian biodiversity hotspots, and the in-situ vs ex-situ distinction with examples. The evil quartet of biodiversity loss is a frequent question framework. Solve PYQs from the last 5 years — the same concepts recycle.
NEET loves asking for India-specific facts: 4 hotspots, 14 biosphere reserves, 106 national parks, 567 wildlife sanctuaries. You don’t need all numbers, but knowing there are 4 hotspots and being able to name them is worth 4 easy marks over your NEET career.
Common Traps
Trap 1 — In-situ means conservation in the natural habitat; ex-situ means outside. National parks, wildlife sanctuaries, and biosphere reserves are in-situ. Zoos, botanical gardens, seed banks, and cryopreservation are ex-situ. Don’t mix them up.
Trap 2 — The Z value of 0.6-1.2 is for large areas (continents/islands), not normal regions. Within a continent, Z is 0.1-0.2. The jump to 0.6-1.2 happens when comparing species across entire continents or isolated islands.
Trap 3 — Habitat loss is the BIGGEST cause of biodiversity loss, not overexploitation. The “evil quartet” is: habitat loss and fragmentation (primary cause), overexploitation, alien species invasion, and co-extinction. NEET asks which is the most significant.
Trap 4 — Endemism means found ONLY in that region, not just “common there.” A species is endemic to an area if it occurs nowhere else on Earth. High endemism is a key criterion for biodiversity hotspot designation.