Q.Select the correct option : (A) Tropics between 23.5° N – 23.5° S –– Higher biodiversity than temperate areas (B) Columbia –– 105 bird species (C) New York –– 1400 bird species (D) India –– 2000 bird species

Let's walk through each option carefully. The question tests your grasp of biodiversity facts — specifically, numbers that are often quoted in discussions of species richness and conservation.

Option (A): Mega diversity countries in the world – 12

This is correct. The term "mega diversity countries" refers to a small group of nations that together harbour the majority of Earth's species. This figure of 12 is the standard one used in the NCERT/Indian Class 12 Biology textbook, and the question follows that textbook convention.

Option (B): Genetically different strains of rice in India – Less than 1000

This is the clear mismatch. India is one of the centres of origin of rice (Oryza sativa). Traditional varieties and landraces number in the tens of thousands. The figure commonly cited is over 50,000 genetically distinct strains of rice found in India. Saying "less than 1000" is a gross underestimate. This pair is wrong.

Option (C): Robert May's estimation on global species diversity – 7 million species worldwide

This is correct. The British ecologist Robert May, in the 1990s, estimated that the total number of species on Earth is around 7 million (with many still undiscovered). This is a standard reference point in biodiversity discussions.

Option (D): Zoological parks – Ex-situ conservation

This is correct. Zoological parks (zoos) are classic examples of ex-situ conservation — conserving species outside their natural habitats. The other main category is in-situ conservation (e.g., national parks, wildlife sanctuaries).

The question tests your understanding of global biodiversity patterns, specifically how species richness varies across latitudes and geographies. At its heart lies a fundamental ecological principle: life proliferates most abundantly near the equator and thins out as you move toward the poles.

The tropics, defined by the belt between the Tropic of Cancer (23.5° N) and the Tropic of Cancer (23.5° S), represent Earth's most biodiverse regions. This isn't a minor difference—tropical forests, though covering only about 7% of the planet's land surface, contain more than half of all terrestrial species. The reasons are multiple: year-round warmth, abundant rainfall, stable climatic conditions over millions of years, and complex forest structures that create countless ecological niches. A single hectare of tropical rainforest can contain more tree species than all of North America combined.

Temperate regions, by contrast, experience harsh seasonal swings, shorter growing seasons, and a history of recent glaciation that repeatedly wiped out species. The result is a dramatic latitudinal gradient in biodiversity—one of ecology's most robust patterns.

Now let's examine the specific claims about bird species:

• Colombia (not "Columbia") is one of the world's megadiverse countries, sitting astride the equator with Amazon rainforest, Andean mountains, and Pacific and Caribbean coasts. It hosts over 1,900 bird species—the highest bird diversity of any nation on Earth. The figure of 105 is wildly incorrect.

• New York State, a temperate region, records roughly 480 bird species cumulatively (including migrants and vagrants). The claim of 1,400 is inflated by nearly threefold.

• India, spanning tropical and subtropical zones with diverse habitats from the Himalayas to the Western Ghats, harbours approximately 1,300 bird species. The figure of 2,000 overshoots reality.

Option (A) stands as a statement of ecological fact, grounded in decades of biogeographic research. The other options contain numerical errors that disqualify them.

While more than 1.5 million species have been described and recorded so far, the actual number of species on Earth is much higher. Using statistical/comparison techniques, ecologist Robert May made a more conservative and scientifically sound estimate of the global species diversity at about 7 million. (Some other estimates ranged as wide as 20-50 million.) Edward Wilson is famous for popularising the term biodiversity; Paul Ehrlich and David Tilman are known for other ecological contributions, but the ~7 million figure is credited to Robert May.

Based on the currently available species inventories, of all the recorded species, about 70% are animals, while plants (including algae, fungi, bryophytes, gymnosperms and angiosperms) make up only about 22%. Among animals, insects are the most species-rich group, constituting more than 70% of the total animals recorded.