NEET Biodiversity and Conservation Previous Year Questions with Solutions

The largely tropical Amazonian rain forest in South America harbors the greatest biodiversity on Earth. NCERT lists the exact documented species counts:

• • Invertebrates comprise the largest biological diversity slice.

Sorting the groups from greatest number of species to smallest number of species gives:

• • 125,000 > 40,000 > 3,000 > 1,300 > 427.

Comparing with options: Option (1) starts with (c); Option (2) displays: (d) > (a) > (c) > (b) > (e); Option (3) starts with (e); Option (4) starts with (b). Option (2) is uniquely correct.

• • Matches official NTA final answer key Option B / (2).

Ex-situ conservation involves the protection of endangered genetic materials, species, or organisms outside their natural habitats:

• • Used when a species is facing an imminent threat of extinction in the wild and requires urgent, intensive human intervention.

Classify each choice into in-situ or ex-situ categories:

• • National Parks: Strictly reserved for wild species in their natural habitat (In-situ).
• • Wildlife Sanctuaries: Natural wild tract with regulated human activities (In-situ).
• • Zoos and Botanical Gardens: Artificial enclosures maintaining living captive animals and cultivated plant collections (Ex-situ).
• • Matches Option (3).

Correlating each term from NCERT Chapter 15:

• • A. The Evil Quartet: The four major anthropogenic drivers of accelerated species extinctions: (1) Habitat loss and fragmentation, (2) Over-exploitation, (3) Alien species invasions, and (4) Co-extinctions. Hence, A matches III (Causes of biodiversity losses).
• • B. Ex situ conservation: Threatened animals and plants are taken out from their natural habitat and placed in special settings where they can be protected and given special care. Advanced ex situ methods include cryopreservation of gametes in viable and fertile conditions for long periods. Hence, B matches I (Cryopreservation).
• • C. *Lantana camara*: An exotic tropical shrub introduced into India as an ornamental plant that aggressively colonized native forests and displaced endemic flora, serving as a textbook example of Alien species invasion (along with water hyacinth / *Eichhornia* and carrot grass / *Parthenium*). Hence, C matches II.
• • D. Dodo (*Raphus cucullatus*): An extinct flightless bird endemic to the island of Mauritius that succumbed to extinction due to human over-hunting and predation by introduced domestic animals. Hence, D matches IV (Extinction).

Synthesizing the code:

• • A -> III (The Evil Quartet - Causes of biodiversity losses)
• • B -> I (Ex situ conservation - Cryopreservation)
• • C -> II (Lantana camara - Alien species invasion)
• • D -> IV (Dodo - Extinction)

The unambiguous combination is A-III, B-I, C-II, D-IV, matching Option (2).

The International Union for Conservation of Nature and Natural Resources (IUCN, also known as the World Conservation Union) is the global authority on the status of the natural world and the measures needed to safeguard it.

The IUCN Red List of Threatened Species compiles comprehensive information on the global extinction risk of species of animals, plants, and fungi, categorizing taxa from Least Concern to Extinct.

Conservation of biodiversity is divided into two fundamental approaches: in-situ (on-site conservation in natural protected areas like national parks, sanctuaries, biosphere reserves) and ex-situ (off-site conservation in zoological parks, botanical gardens, safari parks, seed banks).

The description "threatened species are taken out from their natural habitat and placed in special setting where they can be protected and given special care" defines ex-situ conservation.

Ex-situ conservation is a major modality of Biodiversity conservation. Option (3) is in-situ (incorrect), Option (1) is molecular biology, Option (2) is resource management. Thus, Option (4) Biodiversity conservation is the intended correct choice.

NCERT designates the four major causes of accelerated species extinction as 'The Evil Quartet': 1. Habitat loss and fragmentation 2. Over-exploitation 3. Alien species invasions 4. Co-extinctions

- Statement A (Over-exploitation): Included in the Quartet. - Statement B (Co-extinction): Included in the Quartet. - Statement C (Endemism): Refers to species confined to a particular area; not a destructive cause. - Statement D (Habitat loss and fragmentation): The most important cause in the Quartet.

Statements A, B, and D represent Evil Quartet causes, giving A, B and D only (Option 2).

Evolutionary biologists and ecologists propose three major hypotheses for greater species diversity in tropics: 1. Speciation is generally a function of time. Temperate regions were subjected to frequent glaciations in the past, while tropical latitudes remained relatively undisturbed for millions of years, having prolonged evolutionary time (Statement A). 2. Tropical environments are less seasonal, relatively more constant and predictable (unlike temperate zones). Such constant environments promote niche specialization and lead to greater species diversity (Statements D and E). 3. There is more solar energy available in the tropics, contributing to higher productivity, which indirectly supports greater diversity (Statement C).

Statement B asserts that "tropics are more seasonal", which directly contradicts ecological reality and NCERT text (tropics are less seasonal).

Statements A, C, D, and E are correct explanations, matching Option (3).

Robert May placed the global species diversity at a conservative and scientifically sound estimate of about 7 million (A -> III). Alexander von Humboldt observed that within a region, species richness increased with increasing explored area up to a limit (Species-Area relationship) (B -> I).

Stanford ecologist Paul Ehrlich used an airplane analogy ('rivet popper hypothesis') to explain the consequences of species extinction on ecosystem functioning (C -> IV). David Tilman’s long-term ecosystem experiments using outdoor plots provided empirical evidence linking species richness to ecosystem stability and biomass constancy (D -> II).

The resulting sequence is A-III, B-I, C-IV, D-II, matching Option (4).

The Evil Quartet comprises four major anthropogenic drivers responsible for accelerated species extinction rates:

Habitat loss directly destroys home ranges, breeding territories, and foraging habitats. NCERT notes that tropical rain forests once covering over $14\%$ of the earth's land surface now cover no more than $6\%$. Fragmentation isolates populations, leading to inbreeding depression and local extinctions.

While over-exploitation (Steller's sea cow, passenger pigeon), alien invasions (Nile perch, water hyacinth), and co-extinctions (obligate mutualists) cause extinctions, habitat destruction universally affects the largest number of taxa simultaneously.

The historic United Nations Conference on Environment and Development (UNCED), widely known as "The Earth Summit", was convened in Rio de Janeiro, Brazil, in 1992:

The Earth Summit called upon all nations to take appropriate measures for the conservation of biodiversity and the sustainable utilization of its benefits.

In a follow-up ten years later, the World Summit on Sustainable Development was held in 2002 in Johannesburg, South Africa, where 190 countries pledged to achieve significant reductions in the rate of biodiversity loss by 2010.

Biologists have documented and cataloged over 1.5 million species according to IUCN (2004). However, an enormous fraction of biodiversity (especially in the tropics and among insects/nematodes) remains undiscovered: - Some extreme speculative calculations suggested the existence of 20 to 50 million species. - The theoretical ecologist Robert May applied rigorous insect-host specificity ratios and species-area relationships to formulate a conservative and scientifically sound estimate placing total global species diversity at approximately 7 million. - Of these estimated 7 million species, only approximately 22% have been scientifically named and recorded so far.

- 1.5 million: The number of currently cataloged/described species according to IUCN (2004), not the total global estimate. - 20 to 50 million: Extreme, highly speculative estimates made by other researchers.

Species richness peaks in the tropics and declines towards the poles. The equatorial Amazonian rainforest in South America exhibits the highest species diversity on the planet due to three fundamental ecological drivers: 1. Evolutionary Stability: Tropical latitudes have remained relatively undisturbed by recurring glaciations over geological epochs, allowing prolonged evolutionary time for explosive speciation. 2. Constant Niche Environment: Tropical climates are less seasonal, relatively constant, and predictable, promoting specialization and greater niche differentiation. 3. Higher Solar Insolation: Enormous year-round solar energy input sustains massive primary productivity, which directly supports complex food webs and high species diversity.

- Western Ghats of India: Exceptionally rich in endemic amphibian biodiversity, but far smaller in total species count than the Amazon basin. - Himalayas & Madagascar: Globally designated biodiversity hotspots with high endemism, but their total species richness is dwarfed by the continental expanse of the Amazon basin.