26 public questions tagged with this topic.
In a forest ecosystem, the pyramid of biomass is always upright because the biomass of producers is greater than that of consumers.
Ref: NCERT Class 12 Biology Chapter 12: Ecosystem Ecological Pyramids - Number Biomass Energy
Availability of food and resources directly affects population size by influencing birth and death rates.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Adaptations - Morphological Physiological Behavioural
Bacteria play a key role in the nitrogen cycle by converting atmospheric nitrogen into forms usable by plants.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Organism and Environment - Major Biomes Abiotic Factors
Resource availability affects population growth, as limited resources lead to competition and population regulation.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Organism and Environment - Major Biomes Abiotic Factors
“Small, far from mainland” for which type of island is expected to have the fewest species. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. At equilibrium, species identities can continue to turn over even when richness is approximately stable. The model predicts a balance of rates, not an absence of colonization or extinction. The remaining alternatives—“Small, near mainland”, “Large, near mainland”, “Large, far from mainland”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Island biogeography explains species richness as a dynamic balance between immigration and extinction. Immigration generally declines as an island fills with species, whereas extinction rises as more species divide finite area and maintain smaller populations. Linking the wording to measurable consequences for fitness, abundance, or flux gives the conclusion its scientific meaning and prevents a purely mnemonic interpretation.
Ref: Biogeography, Lomolino et al., 5th Ed., Ch. 5-8
“Immigration equals extinction” for the equilibrium number of species is achieved when. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. At equilibrium, species identities can continue to turn over even when richness is approximately stable. The model predicts a balance of rates, not an absence of colonization or extinction. The remaining alternatives—“Immigration exceeds extinction”, “Extinction exceeds immigration”, “Immigration stops”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Island biogeography explains species richness as a dynamic balance between immigration and extinction. Immigration generally declines as an island fills with species, whereas extinction rises as more species divide finite area and maintain smaller 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.
Ref: Biogeography, Lomolino et al., 5th Ed., Ch. 5-8
“Phenotypic plasticity” for what is a typical reason non-native species become invasive. 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—“Presence of natural predators”, “Low reproductive rates”, “Specialized diet”—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. 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: NCERT Biology Class 12, Ch. 15 Biodiversity and Conservation
“Indicator species” for species defining environmental traits are called. 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—“Keystone species”, “Flagship species”, “Umbrella species”—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: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 21
The keyed exception is “Less likely to invade species-rich ecosystems.” In the context of characteristic generally not true for invasive species, that statement differs from the governing ecological pattern and must be evaluated against the mechanism rather than accepted from wording alone. 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. The remaining alternatives—“Greater phenotypic plasticity”, “High dispersal ability”, “High competitive ability”—refer to different states, processes, or scales and therefore do not express the same causal relationship. 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. 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: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 21
The keyed exception is “Influence proportional to abundance.” In the context of incorrect statement about keystone species, that statement differs from the governing ecological pattern and must be evaluated against the mechanism rather than accepted from wording alone. 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—“Species other than consumers can be keystone”, “Removal reduces species richness”, “Removal causes trophic cascades”—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.
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 21
“Invasive” for high dispersal ability and competitive ability species likely become. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. 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. The remaining alternatives—“Endangered”, “Dominant”, “Specialist”—refer to different states, processes, or scales and therefore do not express the same causal relationship. 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 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
“Wetlands” for preferred habitat for eichhornia crassipes is. 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—“Arid habitats”, “Tropical forests”, “Mountain regions”—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: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 21
