10 public questions tagged with this topic.
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
Invasive species can significantly impact ecosystem dynamics by disrupting food chains and reducing biodiversity.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Adaptations - Morphological Physiological Behavioural
Invasive species often reduce biodiversity by outcompeting native species and disrupting ecosystem balance.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Responses to Abiotic Factors - Regulate Conform Migrate Suspend
“Population size of prey” for top predators impact ecosystems by controlling. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Evidence should connect encounter rates or resource use to survival, growth, or reproduction. The ecological label follows that causal effect rather than superficial proximity between organisms. The remaining alternatives—“Nutrients”, “Primary productivity”, “Abiotic factors”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Species interactions are classified by their net effects on the fitness of each participant, but those effects can change with density, resource supply, life stage, and environmental stress. Competition reduces access to shared limiting factors, whereas predation and parasitism transfer resources from victim to consumer. Field observations could test this account by measuring the proposed driver and the demographic or ecosystem response while controlling plausible confounding factors.
Ref: Fundamentals of Ecology, Odum & Barrett, 5th Ed., Ch. 4
“Generally invade easily” for invasive species in diversity-rich ecosystems. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Diversity can influence ecosystem functioning through complementarity, facilitation, and insurance among species, although the relationship depends on which traits are represented rather than species number alone. The remaining alternatives—“Always fail”, “Quick extinction”, “Enhance native richness”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Biodiversity has complementary components. Richness counts entities, evenness describes their relative abundances, and turnover measures compositional change across space or time; no single index captures all three. The cited framing is therefore most useful when treated as a conditional biological claim, with assumptions about scale and environmental context kept explicit. Linking the wording to measurable consequences for fitness, abundance, or flux gives the conclusion its scientific meaning and prevents a purely mnemonic interpretation.
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 21
“Keystone species” for species disproportionately affecting environments. 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—“Indicator species”, “Flagship species”, “Umbrella species”—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. This distinction matters because similar surface patterns can arise through different mechanisms, whereas ecological prediction depends on identifying the mechanism that actually changes rates. The cited framing is therefore most useful when treated as a conditional biological claim, with assumptions about scale and environmental context kept explicit.
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 21
“High competition and rapid reproduction” for invasive species typically become problematic because of their. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Management outcomes depend on scale and context: suppressing abundance at one site does not guarantee regional eradication when dispersal reconnects treated and untreated populations. The remaining alternatives—“Low dispersal ability”, “Specialized dietary habits”, “Strict habitat requirements”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Species management must identify the demographic stage and ecological process that most strongly limits population growth. Prevention, early detection, removal, habitat manipulation, and biological control act at different points in an invasion or recovery trajectory. Linking the wording to measurable consequences for fitness, abundance, or flux gives the conclusion its scientific meaning and prevents a purely mnemonic interpretation. Field observations could test this account by measuring the proposed driver and the demographic or ecosystem response while controlling plausible confounding factors.
Ref: NCERT Biology Class 12, Ch. 15 Biodiversity and Conservation
“Island birds” for introduction of predators like rats and cats most affects. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Extinction risk rises when abundance, geographic range, or genetic variation becomes small because demographic chance, environmental fluctuations, inbreeding, and rare catastrophes then have disproportionate effects. Correlated losses among subpopulations further weaken regional persistence. The remaining alternatives—“Marine mammals”, “Terrestrial reptiles”, “Amphibians”—refer to different states, processes, or scales and therefore do not express the same causal relationship. The mechanism should be evaluated across both local and global scales. Local disappearance can be reversed by recolonization, whereas global extinction is irreversible and requires the loss of every surviving population. 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: Conservation Biology, Primack & Sher, 6th Ed., Ch. 7
The rivet hypothesis predicts accumulating, often stepwise deterioration as species are removed. Individual losses may initially have small effects, yet each removes part of the system's functional support, so resilience and performance decline and eventual collapse becomes increasingly likely. Species richness counts taxa but does not show their abundance, traits, or interaction strengths. Dominant species may control bulk process rates, rare species may provide specialized functions or future insurance, and predators can restructure whole food webs through indirect effects. Functional groups summarize role overlap, while keystone effects identify unusually strong influence. Separating these dimensions explains why equal losses of richness can have very different ecological consequences and why conservation cannot rely solely on the number of species remaining. In this context, the keyed term, Gradual, stepwise decline, identifies the relevant mechanism or quantitative relationship and links the observed pattern to its underlying ecological cause. The distinction is testable by measuring changes in organisms, resources, or process rates through time rather than relying on the label alone.
Ref: NCERT Biology Class 12, Ch. 15 Biodiversity and Conservation
Eutrophication is enrichment of water with nutrients, especially phosphorus in many fresh waters and nitrogen in many coastal systems. The added nutrients remove a growth limitation on phytoplankton or cyanobacteria, allowing rapid population increase that appears as an algal bloom. Dense blooms reduce water clarity and shade submerged vegetation. When algal cells die, bacteria decompose the organic matter and consume dissolved oxygen; stratified bottom waters may then become hypoxic or anoxic. Fish kills, loss of oxygen-sensitive species, toxin-producing cyanobacteria, unpleasant odours, and altered food webs may follow. Nutrient enrichment can initially increase biomass or the abundance of a few species, but it does not reliably boost biodiversity and often reduces it through dominance and oxygen stress. Clear water and higher oxygen are therefore opposite to the common late consequences. Natural eutrophication occurs slowly as basins age, whereas fertilizer, manure, sewage, and urban runoff can accelerate it dramatically. The bloom is the immediate visible response because nutrient supply raises photosynthetic growth before decomposition generates oxygen depletion.
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 2-3
