10 public questions tagged with this topic.
Invasive species can outcompete native species, leading to reduced biodiversity and ecosystem imbalance.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Organism and Environment - Major Biomes Abiotic Factors
Untreated sewage increases BOD, reducing oxygen levels in water and harming aquatic life.
Ref: NCERT Class 12 Biology Chapter 8: Microbes in Human Welfare Microbes in Human Welfare - Overview and Significance
“Parthenium hysterophorus” for which invasive species is known as 'congress grass'. 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—“Eichhornia crassipes”, “Prosopis juliflora”, “Lantana camara”—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
“Anthropogenic extinction” for extinction due to human activity is called. 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—“Mass extinction”, “Demographic extinction”, “Natural extinction”—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: Conservation Biology, Primack & Sher, 6th Ed., Ch. 7
“0.36” for habitat destruction causes what percent of extinctions. 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—“0.23”, “0.434”, “0.38”—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. 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: Conservation Biology, Primack & Sher, 6th Ed., Ch. 7
Detection of microplastics in fish and shellfish provides a credible human-exposure pathway because these organisms are eaten, sometimes whole. The observation establishes potential dietary contact, although it does not by itself quantify absorbed dose or prove a particular disease. Risk assessment must distinguish particle presence in gut contents from edible tissues and consider particle size, additives, preparation, consumption rate, and toxicological evidence. Laboratory effects must be interpreted alongside environmentally realistic concentrations, while field detection demonstrates exposure but does not alone prove causation. Prevention requires reducing unnecessary plastic use, improving collection and recycling, controlling lost fishing gear, and limiting releases of fibres and tyre-wear particles. Because conventional polymers persist, fragmentation redistributes plastic into smaller pieces rather than removing its mass from the ecosystem. Trophic transfer can occur when predators consume contaminated prey, although evidence for consistent biomagnification of particle numbers remains system-dependent. Standardised sampling and contamination controls are essential because airborne fibres can enter samples during collection and laboratory processing.
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
Plastic ingestion affects marine birds, mammals, turtles, and fish, as well as many invertebrates. Animals may mistake fragments for prey or ingest particles indirectly through contaminated food. Consequences include gut blockage, false satiation, reduced body condition, tissue injury, and exposure to additives or sorbed contaminants. Restricting the effect to one group ignores extensive observations across trophic levels and feeding modes. Trophic transfer can occur when predators consume contaminated prey, although evidence for consistent biomagnification of particle numbers remains system-dependent. Standardised sampling and contamination controls are essential because airborne fibres can enter samples during collection and laboratory processing. Particle size, shape, polymer type, weathering state, and associated chemicals all influence uptake and biological response, so microplastics are not a uniform toxicant. Laboratory effects must be interpreted alongside environmentally realistic concentrations, while field detection demonstrates exposure but does not alone prove causation. Prevention requires reducing unnecessary plastic use, improving collection and recycling, controlling lost fishing gear, and limiting releases of fibres and tyre-wear particles.
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
Microplastics are conventionally defined as plastic particles smaller than 5 millimetres. Primary microplastics are manufactured at small size, such as some industrial pellets and microbeads, whereas secondary microplastics form when larger objects fragment. The category includes fibres, films, foams, and irregular fragments of varied polymers. Small size promotes ingestion by many organisms, but the particles are not necessarily invisible, organic toxins, or biodegradable materials. Prevention requires reducing unnecessary plastic use, improving collection and recycling, controlling lost fishing gear, and limiting releases of fibres and tyre-wear particles. Because conventional polymers persist, fragmentation redistributes plastic into smaller pieces rather than removing its mass from the ecosystem. Trophic transfer can occur when predators consume contaminated prey, although evidence for consistent biomagnification of particle numbers remains system-dependent. Standardised sampling and contamination controls are essential because airborne fibres can enter samples during collection and laboratory processing. Particle size, shape, polymer type, weathering state, and associated chemicals all influence uptake and biological response, so microplastics are not a uniform toxicant.
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
Plastic constitutes most persistent marine debris by item count in many surveys because production and disposal volumes are enormous, buoyant products travel far, and polymers degrade very slowly. Bags, bottles, fishing gear, packaging, and fragments remain in coastal and open-ocean systems for years. Glass and metal also occur but are generally less abundant and may sink or corrode; organic waste decomposes much more readily. Laboratory effects must be interpreted alongside environmentally realistic concentrations, while field detection demonstrates exposure but does not alone prove causation. Prevention requires reducing unnecessary plastic use, improving collection and recycling, controlling lost fishing gear, and limiting releases of fibres and tyre-wear particles. Because conventional polymers persist, fragmentation redistributes plastic into smaller pieces rather than removing its mass from the ecosystem. Trophic transfer can occur when predators consume contaminated prey, although evidence for consistent biomagnification of particle numbers remains system-dependent. Standardised sampling and contamination controls are essential because airborne fibres can enter samples during collection and laboratory processing.
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
Estrogens, including natural hormones and synthetic pharmaceutical analogues, can shift fish sex ratios by altering endocrine signalling during sensitive developmental periods. Exposure may induce vitellogenin in males, create intersex gonads, feminise genetic males, reduce sperm quality, and lower reproductive success. Fertilisers chiefly alter nutrient status, while heavy metals and chlorinated hydrocarbons have other toxic actions, although some compounds in those groups can also disrupt endocrine systems. Aquatic effects depend on chemical form, persistence, solubility, dose, and the capacity of organisms to metabolise or excrete the substance. Catchment processes connect land use with rivers, lakes, estuaries, and coastal waters, so prevention at the source is usually more effective than downstream treatment. Ecological assessment distinguishes hazard from risk: a substance may be intrinsically harmful, but realised impact also requires sufficient environmental exposure. Sensitive developmental stages may respond at concentrations that cause little immediate adult mortality, making reproduction and recruitment essential endpoints. Monitoring should include appropriate controls, spatial replication, temporal variation, and validated analytical methods before broad conclusions are drawn.
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
