• The forests occurring in tropical areas of heavy rainfall are known as tropical rain forests. It has abundant species of wildlife and vegetation.
• Previously 14 percent of the Earth ’s land surface was covered by the tropical rain forests.

Tomato, potato, Brinjal etc. belongs to genus Solanum although they are of diverse forms. This variation in form represent species diversity belonging to same genus.

‘The Evil Quartet ’is the sobriquet used to describe the reasons for the decline in the number of species. The four reasons include Loss of habitat and fragmentation, Over-exploitation of species, Invasion of alien (new) species and Co-extinctions.

Wetland provide benefits like prevention from flood and recharge ground water, social, economic and environmental benefits and being rich in nutrients, they provide a diverse and productive ecosystem.

Biodiversity can be classified on the basis of community, habitat and landscape but not on the basis of population of particular species in the biosphere.

• The forests occurring in tropical areas of heavy rainfall are known as tropical rain forests. It has abundant species of wildlife and vegetation.
• Currently, 6 percent area of the Earth ’s land surface is covered by the tropical rain forests.

The excess and unsustainable use of resources is known as over-exploitation. It is also known as overharvesting. Overexploitation of any kind of resource leads to rapid decline and destruction of that resource that may cause serious damage to the ecosystem.

In food chain, each organism has its own role in flow of energy and nutrient cycle. If snakes become extinct the loss will make the biological network imbalanced. Their gene pool will lost forever that results into loss of biodiversity.

The pattern of species diversity on earth is not uniformly distributed. Species variation is generally highest in the tropics and decreases towards the poles due to variation in temperature.

• The unintentional or deliberate introduction of alien (new) species into a habitat cause the aliens to turn invasive and thus causing the decline or extinction of indigenous species.
• They can affect all types of organisms (animals, plants, fungi, and microorganisms) and ecosystems.