SPECIES

SPECIES

An invasive species that acts as a carrier of plant pathogens is:

“Achatina fulica” for an invasive species that acts as a carrier of plant pathogens 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—“Nile perch”, “Cane toad”, “Zebra mussel”—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: NCERT Biology Class 12, Ch. 15 Biodiversity and Conservation

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Umbrella species typically require:

“Extensive territories for viable populations” for umbrella species typically require. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Ecological interpretation requires separating the immediate process from its broader consequence. A mechanism operating through physiology or behavior can scale up to alter survival, reproduction, abundance, distribution, and community structure. The remaining alternatives—“Small habitats”, “Limited resources”, “Highly specialized diets”—refer to different states, processes, or scales and therefore do not express the same causal relationship. The inference is strongest when the relevant variables, spatial boundary, and time scale are explicit. Context can alter the magnitude of an effect without changing the definition of the focal concept. 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

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Which species is not an invasive plant in India?

The keyed exception is “Nelumbo nucifera.” In the context of which species is not an invasive plant in india, that statement differs from the governing ecological pattern and must be evaluated against the mechanism rather than accepted from wording alone. 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—“Mikania micrantha”, “Parthenium hysterophorus”, “Eichhornia crassipes”—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. 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: NCERT Biology Class 12, Ch. 15 Biodiversity and Conservation

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Dominant species typically have:

“Large biomass and high abundance” for dominant species typically have. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. A sound explanation connects the stated pattern to a causal pathway and distinguishes it from alternatives that describe different levels of organization or different ecological processes. The remaining alternatives—“Low ecological impact”, “Narrow dietary preferences”, “Few interactions with other species”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Ecological interpretation requires separating the immediate process from its broader consequence. A mechanism operating through physiology or behavior can scale up to alter survival, reproduction, abundance, distribution, and community structure. 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

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SPECIES

A species causing ecosystem changes despite being few in number is classified as a:

“Keystone species” for a species causing ecosystem changes despite being few in number is classified as a. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Ecosystem processes are constrained by energy conservation and by the cycling of matter. Energy enters mainly through primary production, is lost as metabolic heat at every transfer, and therefore cannot be recycled in the way that carbon, nitrogen, phosphorus, or water can. The remaining alternatives—“Dominant species”, “Invasive species”, “Indicator species”—refer to different states, processes, or scales and therefore do not express the same causal relationship. The relevant inference should follow the pathway from resource supply to organismal uptake and then to ecosystem-level flux. Productivity, trophic transfer, decomposition, and nutrient regeneration are connected, but each measures a different part of that pathway. 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

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SPECIES

Which plant invaded India via contaminated PL-480 wheat imports?

“Parthenium hysterophorus” for which plant invaded india via contaminated pl-480 wheat imports. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Ecological interpretation requires separating the immediate process from its broader consequence. A mechanism operating through physiology or behavior can scale up to alter survival, reproduction, abundance, distribution, and community structure. The remaining alternatives—“Eichhornia crassipes”, “Prosopis juliflora”, “Lantana camara”—refer to different states, processes, or scales and therefore do not express the same causal relationship. The inference is strongest when the relevant variables, spatial boundary, and time scale are explicit. Context can alter the magnitude of an effect without changing the definition of the focal concept. 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: NCERT Biology Class 12, Ch. 15 Biodiversity and Conservation

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SPECIES

Species that reflect the biotic state of an environment and indicate changes in ecosystems are called:

“Indicator species” for species that reflect the biotic state of an environment and indicate changes in ecosystems are called. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. The relevant inference should follow the pathway from resource supply to organismal uptake and then to ecosystem-level flux. Productivity, trophic transfer, decomposition, and nutrient regeneration are connected, but each measures a different part of that pathway. The remaining alternatives—“Specialist species”, “Flagship species”, “Umbrella species”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Rates depend on temperature, moisture, substrate quality, consumer physiology, and the elemental balance between organisms and their food. These controls explain why the same process can differ among terrestrial, freshwater, and marine systems without changing its definition. 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

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What is the main advantage of generalist species under changing environmental conditions?

“Adaptability to various habitats and food sources” for what is the main advantage of generalist species under changing environmental conditions. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. The inference is strongest when the relevant variables, spatial boundary, and time scale are explicit. Context can alter the magnitude of an effect without changing the definition of the focal concept. The remaining alternatives—“Highly specialized diet”, “Narrow niche occupation”, “Low reproductive rate”—refer to different states, processes, or scales and therefore do not express the same causal relationship. A sound explanation connects the stated pattern to a causal pathway and distinguishes it from alternatives that describe different levels of organization or different ecological processes. Linking the wording to measurable consequences for fitness, abundance, or flux gives the conclusion its scientific meaning and prevents a purely mnemonic interpretation.

Ref: NCERT Biology Class 12, Ch. 15 Biodiversity and Conservation

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Lantana camara negatively impacts other plants primarily through:

“Allelopathy” for lantana camara negatively impacts other plants primarily through. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. The inference is strongest when the relevant variables, spatial boundary, and time scale are explicit. Context can alter the magnitude of an effect without changing the definition of the focal concept. The remaining alternatives—“Competition for sunlight”, “Rapid growth rate only”, “Toxic fruit ingestion”—refer to different states, processes, or scales and therefore do not express the same causal relationship. A sound explanation connects the stated pattern to a causal pathway and distinguishes it from alternatives that describe different levels of organization or different ecological processes. 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

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What role does the sea otter play in kelp forest ecosystems?

“Keystone predator” for what role does the sea otter play in kelp forest ecosystems. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Rates depend on temperature, moisture, substrate quality, consumer physiology, and the elemental balance between organisms and their food. These controls explain why the same process can differ among terrestrial, freshwater, and marine systems without changing its definition. The remaining alternatives—“Primary producer”, “Dominant herbivore”, “Generalist species”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Ecosystem processes are constrained by energy conservation and by the cycling of matter. Energy enters mainly through primary production, is lost as metabolic heat at every transfer, and therefore cannot be recycled in the way that carbon, nitrogen, phosphorus, or water can. 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

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The Giant African Snail (Achatina fulica) was initially introduced to India from:

“Mauritius” for the giant african snail (achatina fulica) was initially introduced to india from. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. The inference is strongest when the relevant variables, spatial boundary, and time scale are explicit. Context can alter the magnitude of an effect without changing the definition of the focal concept. The remaining alternatives—“Africa”, “South America”, “Australia”—refer to different states, processes, or scales and therefore do not express the same causal relationship. A sound explanation connects the stated pattern to a causal pathway and distinguishes it from alternatives that describe different levels of organization or different ecological processes. 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

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Which species introduction nearly caused extinction of cichlids in Lake Victoria?

“Nile perch” for which species introduction nearly caused extinction of cichlids in lake victoria. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Human-driven habitat conversion, exploitation, introduced enemies, pollution, and climate change often interact rather than acting independently. Traits such as slow reproduction or ecological specialization can magnify vulnerability. The remaining alternatives—“Cane toads”, “Zebra mussels”, “Prosopis juliflora”—refer to different states, processes, or scales and therefore do not express the same causal relationship. 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. 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

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