Biodiversity refers to the variety of life on Earth, including plants, animals, microorganisms, and the ecosystems they form. Conservation is the process of protecting and maintaining this biodiversity for present and future generations. The chapter “Biodiversity and Conservation” in Class 12 Biology explores the meaning, significance, threats, and strategies related to the protection of biodiversity. Understanding this chapter is not only important for exams but also crucial for developing awareness about the importance of nature in our lives.
Biodiversity and Conservation Class 12 Biology | Short & Long Questions
What is Biodiversity?
Definition of Biodiversity
Biodiversity can be defined as the total variety of organisms present on Earth, including their genetic variations and the ecosystems they form.
Levels of Biodiversity
Biodiversity can be studied at three different levels:
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Genetic Diversity – Variability in the genetic makeup among individuals of the same species.
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Example: Different varieties of rice or wheat, different breeds of dogs.
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Species Diversity – Variety of species within a region or ecosystem.
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Example: A rainforest has more species diversity than a desert.
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Ecosystem Diversity – Variety of ecosystems in a given geographical area.
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Example: Deserts, forests, wetlands, coral reefs.
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Global and National Biodiversity
Global Biodiversity
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According to IUCN (International Union for Conservation of Nature), there are about 1.7 to 1.8 million species known to science.
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Estimates suggest the actual number could be more than 10 million species on Earth.
India as a Mega Diversity Nation
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India is among the 12 mega diversity countries in the world.
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With only 2.4% of the Earth’s land area, India accounts for 8.1% of global species diversity.
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Major biodiversity-rich regions: Himalayas, Indo-Burma region, Indo-Malayan region, and the Indo-Pacific region.
Patterns of Biodiversity
Latitudinal Gradient
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Biodiversity is highest in tropical regions and decreases towards the poles.
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Example: Tropical rainforests of Amazon are rich in species diversity compared to polar regions.
Species-Area Relationship
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Proposed by Alexander von Humboldt.
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Species richness increases with increasing area, but only up to a limit.
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Mathematically expressed as:
S = C A^Z
where,
S = Species richness
A = Area
C = Constant
Z = Regression coefficient
Importance of Biodiversity
Ecological Roles
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Maintains ecological balance.
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Provides stability to ecosystems.
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Ensures nutrient cycling, soil formation, and pollination.
Economic Value
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Food and Crops – Cereals, pulses, fruits, vegetables.
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Medicines – More than 25% of drugs are derived from plants (e.g., quinine, morphine).
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Industrial Products – Rubber, timber, resins, oils.
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Recreational Value – Tourism, bird watching, nature trails.
Ethical Value
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Every species has a right to exist.
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Biodiversity should be preserved for future generations.
Loss of Biodiversity
Causes of Biodiversity Loss
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Habitat Loss and Fragmentation
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Conversion of forests into agricultural land, urbanization, and industrialization.
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Fragmentation of habitats reduces genetic exchange among species.
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Over-exploitation
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Excessive hunting, fishing, logging.
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Example: Extinction of passenger pigeon due to overhunting.
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Alien Invasive Species
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Introduction of non-native species disturbs natural ecosystems.
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Example: Eichhornia (water hyacinth) and Lantana.
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Co-extinction
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Extinction of one species leads to extinction of another dependent species.
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Example: Parasites die when their host species becomes extinct.
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Pollution and Climate Change
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Industrial pollution, pesticides, global warming, and ozone depletion threaten biodiversity.
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Biodiversity Conservation
Why Conserve Biodiversity?
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Narrow utilitarian values (food, medicine, fuel).
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Broad utilitarian values (ecosystem services like oxygen production).
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Ethical responsibility to protect other life forms.
Methods of Conservation
In-situ Conservation (On-site)
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Conserving species in their natural habitats.
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Examples:
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Protected Areas – National Parks, Wildlife Sanctuaries, Biosphere Reserves.
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Hotspots of Biodiversity – Regions rich in endemic species and under threat.
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India has 4 biodiversity hotspots: Himalaya, Indo-Burma, Indo-Malayan, and Indo-Pacific regions.
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Sacred Groves – Forest patches protected by local communities due to religious beliefs.
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Ex-situ Conservation (Off-site)
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Conserving species outside their natural habitats.
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Examples:
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Botanical Gardens and Zoological Parks.
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Gene Banks and Seed Banks.
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Cryopreservation – Preserving gametes, seeds, and embryos at very low temperatures.
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Important Indian Conservation Efforts
Protected Area Network in India
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National Parks – 104
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Wildlife Sanctuaries – 566
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Biosphere Reserves – 18
Major Conservation Projects
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Project Tiger – Launched in 1973 to protect Bengal tigers.
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Crocodile Conservation Project.
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Project Elephant.
IUCN Red Data Book
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A comprehensive list of species facing risk of extinction.
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Categories:
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Critically Endangered
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Endangered
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Vulnerable
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Extinct
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Sacred Groves and Traditional Conservation Practices
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Sacred groves are forest areas protected by communities due to religious beliefs.
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Found in states like Meghalaya, Rajasthan, Kerala.
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These groves are biodiversity-rich and harbor many endemic species.
Key Concepts to Remember
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Biodiversity levels – Genetic, Species, Ecosystem.
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Patterns – Latitudinal gradient, species-area relationship.
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Causes of biodiversity loss – Habitat loss, over-exploitation, invasive species, pollution, co-extinction.
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Conservation methods – In-situ (protected areas, hotspots, sacred groves), Ex-situ (seed banks, gene banks).
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India’s biodiversity – A mega diversity nation with 4 hotspots.
Objective Questions on Biodiversity and Conservation
Q1. The term Biodiversity was popularized by:
a) Edward Wilson
b) Charles Darwin
c) Linnaeus
d) Humboldt
Answer: Edward Wilson
Q2. How many biodiversity hotspots are present in India?
a) 2
b) 3
c) 4
d) 5
Answer: 4
Q3. Species richness increases with increasing:
a) Temperature
b) Area
c) Population
d) Pollution
Answer: Area
Q4. The species–area relationship was studied by:
a) Mendel
b) Edward Wilson
c) Von Humboldt
d) Malthus
Answer: Von Humboldt
Q5. Amazon rainforest is known as the:
a) Earth’s desert
b) Earth’s lungs
c) Earth’s heart
d) Earth’s store
Answer: Earth’s lungs
Q6. The extinction of one species with another is called:
a) Adaptation
b) Co-extinction
c) Co-evolution
d) Migration
Answer: Co-extinction
Q7. The water hyacinth (Eichhornia) is an example of:
a) Endangered species
b) Exotic species
c) Extinct species
d) Endemic species
Answer: Exotic
Q8. Which one is not a cause of biodiversity loss?
a) Habitat loss
b) Over-exploitation
c) Afforestation
d) Alien species invasion
Answer: Afforestation
Q9. The IUCN Red Data Book contains information about:
a) Fossils
b) Endangered species
c) Domesticated animals
d) Cultivated plants
Answer: Endangered
Q10. Which of the following is an in-situ conservation method?
a) Seed bank
b) Zoological park
c) National park
d) Cryopreservation
Answer: National park
Q11. Project Tiger was launched in the year:
a) 1980
b) 1973
c) 1965
d) 1992
Answer: 1973
Q12. Which is the largest tiger reserve in India?
a) Bandhavgarh
b) Jim Corbett
c) Nagarjunsagar-Srisailam
d) Kaziranga
Answer: Nagarjunsagar-Srisailam
Q13. The total number of National Parks in India is:
a) 66
b) 104
c) 88
d) 52
Answer: 104
Q14. Sacred groves are found in:
a) Himalaya
b) Rajasthan
c) Kerala
d) All of these
Answer: All
Q15. Which is the most biodiversity-rich region?
a) Temperate forests
b) Desert
c) Tropical rainforest
d) Tundra
Answer: Tropical rainforest
Q16. Endangered species are those which:
a) Are extinct
b) Are at high risk of extinction
c) Are abundant
d) Are invasive
Answer: Risk
Q17. The Indian rhinoceros is mainly found in:
a) Madhya Pradesh
b) Assam
c) Tamil Nadu
d) Kerala
Answer: Assam
Q18. Which one is not an ex-situ conservation method?
a) Botanical garden
b) Zoological park
c) Gene bank
d) Biosphere reserve
Answer: Biosphere
Q19. The term “Hotspot” was coined by:
a) Norman Myers
b) Charles Darwin
c) Wallace
d) Linnaeus
Answer: Norman Myers
Q20. The primary cause of biodiversity loss is:
a) Overgrazing
b) Habitat loss
c) Global warming
d) Deforestation
Answer: Habitat
Short Answer Type Questions- Biodiversity and Conservation
Q1. What are the three levels of biodiversity?
Answer: The three levels of biodiversity are Genetic diversity (variation in genes within a species), Species diversity (variety of species in an ecosystem), and Ecosystem diversity (variety of ecosystems in a region).
Q2. Why are tropical regions more diverse than temperate regions?
Answer: Tropical regions have a stable climate, high solar energy input, and constant availability of resources, which promote higher productivity and speciation, making them more diverse than temperate regions.
Q3. What is co-extinction? Give an example.
Answer: Co-extinction is the extinction of one species leading to the extinction of another dependent species. Example: If a host fish species becomes extinct, its parasite species also disappears.
Q4. Define species–area relationship.
Answer: Species–area relationship is the observation that the number of species increases with increasing area, but only up to a limit. It was studied by Alexander von Humboldt and is expressed as S = C A^Z.
Q5. What is the difference between in-situ and ex-situ conservation?
Answer:
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In-situ conservation: Protection of species in their natural habitats (e.g., national parks, sanctuaries).
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Ex-situ conservation: Protection of species outside their natural habitats (e.g., seed banks, zoological parks).
Q6. Name the four biodiversity hotspots of India.
Answer: The four biodiversity hotspots of India are: Indo-Burma region, Indo-Malayan region, Himalaya, and Indo-Pacific region.
Q7. What is the Red Data Book?
Answer: The Red Data Book is published by IUCN and contains a list of species that are endangered, vulnerable, critically endangered, or extinct.
Q8. Write one example each of endangered and invasive species.
Answer:
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Endangered species: Asiatic Lion.
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Invasive species: Eichhornia (Water Hyacinth).
Long Answer Type Questions- Biodiversity and Conservation
Q1. Explain the importance of biodiversity in human life.
Answer: Biodiversity is essential for human survival as it provides food, medicines, fuel, timber, fibers, and industrial raw materials. It maintains ecological balance through nutrient cycling, pollination, climate regulation, and soil fertility. It also has aesthetic and ethical values, promoting ecotourism and preserving nature for future generations. Without biodiversity, ecosystems would collapse and human existence would be threatened.
Q2. Describe the causes of biodiversity loss.
Answer: Major causes of biodiversity loss include:
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Habitat loss and fragmentation – Due to deforestation, urbanization, agriculture.
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Over-exploitation – Excessive hunting, fishing, logging.
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Invasive alien species – Non-native species like Eichhornia and Lantana.
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Pollution – Industrial effluents, pesticides, and global warming.
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Co-extinction – Extinction of one species leading to the extinction of dependent species.
Together, these factors pose a serious threat to biodiversity across the globe.
Q3. Explain the methods of biodiversity conservation.
Answer: Conservation methods are classified into two types:
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In-situ conservation (on-site): Protecting species in their natural habitats. Examples – National parks, Wildlife sanctuaries, Biosphere reserves, Biodiversity hotspots, Sacred groves.
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Ex-situ conservation (off-site): Protecting species outside their natural habitats. Examples – Zoological parks, Botanical gardens, Seed banks, Cryopreservation, Gene banks.
Both methods are necessary for the long-term survival of species.
Q4. Write a note on India as a mega diversity nation.
Answer: India is one of the 12 mega diversity countries in the world, contributing about 8.1% of global biodiversity despite covering only 2.4% of the world’s land area. It has rich flora and fauna due to its varied climate and ecosystems like forests, deserts, wetlands, and coastal regions. The Himalayas, Indo-Burma, Indo-Malayan, and Indo-Pacific regions make India biologically significant. This diversity is protected through numerous national parks, sanctuaries, and biosphere reserves.
Q5. What are biodiversity hotspots? Explain their significance.
Answer: Biodiversity hotspots are regions rich in endemic species (species found nowhere else) and facing serious threat of habitat loss. Norman Myers introduced the concept of hotspots. India has four hotspots – Himalaya, Indo-Burma, Indo-Malayan, and Indo-Pacific regions. These areas are highly important as they contribute significantly to global biodiversity and require urgent conservation measures to prevent extinction of unique species.
Conclusion
Biodiversity forms the foundation of life on Earth. It ensures ecological balance, provides food, medicine, and cultural value, and contributes to economic development. However, due to human activities, biodiversity is under severe threat. Conservation through in-situ and ex-situ methods is essential for the survival of all species, including humans. Protecting biodiversity is not just a scientific necessity but also a moral duty to preserve nature for future generations.