CBSE 2025, Set 2

Question

The world is facing an accelerated rate of species extinctions due to human activities. Explain any three major causes (The Evil Quartet) of biodiversity losses.

Edvaya · Accepted Answer

The correct answer is Subjective. **SOLUTION** Three major causes of biodiversity loss include: 1. **Habitat Loss and Fragmentation:** This is the most critical cause. Massive deforestation leads to outright habitat loss, destroying ecosystems. When large habitats are fragmented into small, isolated patches by human development, mammals and birds requiring large territories suffer heavy population declines. 2. **Overexploitation:** When human "need" turns to "greed," natural resources are heavily overexploited. This unsustainable hunting/harvesting has led to the extinction of many species (e.g., Steller's sea cow, passenger pigeon, and many marine fish populations). 3. **Alien Species Invasions:** When alien (non-native) species are introduced unintentionally or deliberately, some turn highly invasive and aggressively compete with indigenous species, causing their massive decline or extinction (e.g., water hyacinth or *Lantana* weed). *(Note: A fourth valid cause is Co-extinctions, where the extinction of one species invariably leads to the extinction of an associated species in an obligatory mutualistic relationship).*

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Biology > Human Welfare Biotech And Ecology > Biodiversity And Conservation

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