The 'Evil Quartet' represents the major causes of

What could have triggered mass extinctions of species in the past?

Elaborate how invasion by an alien species reduces the species diversity of an area.

Assertion: Tropical rain forests are disappearing fast from developing countries such as India.
Reason: No value is attached to these forests because these are poor in biodiversity.

Give scientific reasons: Habitat loss is the most important cause of the extinction of our wildlife.

Which of the following plants has become a water weed in this country?