12 public questions tagged with this topic.
The four major causes of biodiversity loss are habitat loss and fragmentation, overexploitation, alien species invasions, and co-extinctions.
Ref: NCERT Class 12 Biology Chapter 13: Biodiversity and Conservation Loss of Biodiversity - Causes - Habitat Loss Overexploitation
Large-scale deforestation of the Amazon rainforest has caused extensive habitat loss and biodiversity decline.
Ref: NCERT Class 12 Biology Chapter 13: Biodiversity and Conservation Loss of Biodiversity - Causes - Habitat Loss Overexploitation
Human activities such as habitat loss and fragmentation, overexploitation, alien species invasions, and co-extinctions have greatly accelerated species extinction.
Ref: NCERT Class 12 Biology Chapter 13: Biodiversity and Conservation Loss of Biodiversity - Causes - Habitat Loss Overexploitation
Speciation increases biodiversity. The major causes of biodiversity loss are habitat loss and fragmentation, overexploitation, alien species invasions, and co-extinctions.
Ref: NCERT Class 12 Biology Chapter 13: Biodiversity and Conservation Loss of Biodiversity - Causes - Habitat Loss Overexploitation
Pollination is a beneficial ecosystem service. The major causes of biodiversity loss are habitat loss and fragmentation, overexploitation, alien species invasions, and co-extinctions.
Ref: NCERT Class 12 Biology Chapter 13: Biodiversity and Conservation Loss of Biodiversity - Causes - Habitat Loss Overexploitation
NCERT cites the Passenger pigeon as an example of extinction caused by overexploitation by humans.
Ref: NCERT Class 12 Biology Chapter 13: Biodiversity and Conservation Loss of Biodiversity - Causes - Habitat Loss Overexploitation
Habitat loss and fragmentation is the most important cause of biodiversity loss and has caused most species extinctions during the last 500 years.
Ref: NCERT Class 12 Biology Chapter 13: Biodiversity and Conservation Loss of Biodiversity - Causes - Habitat Loss Overexploitation
According to NCERT, the present extinction rate is 100–1000 times the natural background rate because of habitat loss and fragmentation, overexploitation, alien species invasions, and co-extinctions.
Ref: NCERT Class 12 Biology Chapter 13: Biodiversity and Conservation Loss of Biodiversity - Causes - Habitat Loss Overexploitation
NCERT identifies the "Evil Quartet" as habitat loss and fragmentation, overexploitation, alien species invasions, and co-extinctions. Climate change is not included in this list.
Ref: NCERT Class 12 Biology Chapter 13: Biodiversity and Conservation Loss of Biodiversity - Causes - Habitat Loss Overexploitation
Biodiversity loss reduces productivity, lowers resistance to environmental disturbances, and increases variability in ecosystem processes.
Ref: NCERT Class 12 Biology Chapter 13: Biodiversity and Conservation Biodiversity - Levels - Genetic Species Ecological
“Decreased biodiversity” for common impact of invasive species on native ecosystems. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Effective control reduces propagule pressure or population growth without causing unacceptable non-target effects. Repeated monitoring is necessary because seed banks, dormant stages, recolonization, and density-dependent compensation can reverse short-term gains. The remaining alternatives—“Increased biodiversity”, “Stable ecological niches”, “Enhanced native populations”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Management outcomes depend on scale and context: suppressing abundance at one site does not guarantee regional eradication when dispersal reconnects treated and untreated populations. Field observations could test this account by measuring the proposed driver and the demographic or ecosystem response while controlling plausible confounding factors. This distinction matters because similar surface patterns can arise through different mechanisms, whereas ecological prediction depends on identifying the mechanism that actually changes rates.
Ref: NCERT Biology Class 12, Ch. 15 Biodiversity and Conservation
