9 public questions tagged with this topic.
Population density refers to the number of individuals in a specific area or volume, reflecting the population size in a habitat.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Population Attributes - Birth Death Sex Ratio Age Distribution
The keyed exception is “Endemic species.” In the context of which of these terms does not refer to invasive 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—“Alien species”, “Exotic species”, “Non-native species”—refer to different states, processes, or scales and therefore do not e
Ref: NCERT Biology Class 12, Ch. 15 Biodiversity and Conservation
“Any isolated habitat separated from similar habitats” for what is a habitat island. 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—“An oceanic island”, “A large continent”, “A freshwater lake”—refer to different states, processes, or scales and therefore do not express the same caus
Ref: Biogeography, Lomolino et al., 5th Ed., Ch. 1-4
“Emigration” for movement of individuals out of a population is termed. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Population ecology links individual births, deaths, immigration, and emigration to changes in abundance. Per-capita rates determine the direction of change, while density dependence creates feedback when crowding alters survival or reproduction. The remaining alternatives—“Immigration”, “Dispersion”, “Colonization”—refer to different states, processes, or scales and therefore do
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
The finite rate of increase λ is the ratio of population sizes at successive discrete censuses: λ = N(t+1)/N(t). If censuses are annual, it represents the population multiplication factor per year, often described as annual finite growth. Thus λ = 1.10 means the next year’s population is expected to be 110% of the current one, whereas λ = 0.90 indicates a 10% decline. The time unit is set by the census interval and need not always be a year. Net reproductive rate R0 differs because it measures replacement over a generation, usually expected daughters per female across her lifetime. Carrying ca
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 11
Autotrophic respiration is conventionally written RA because it is respiration performed by primary producers. It represents carbon fixed by photosynthesis that plants or other autotrophs consume for maintenance, ion uptake, biosynthesis, growth, and tissue turnover rather than retaining as new biomass. Ecosystem production is measured over a stated area and interval because it is a flux, not simply material present at one moment. Producers convert inorganic carbon into organic compounds, respiration returns some carbon to the environment, and heterotrophs redistribute and mineralize the remai
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 17
Net community productivity is the net rate at which organic carbon accumulates in an ecosystem after respiration by both autotrophs and heterotrophs. Ecosystem respiration, RE, includes plant respiration plus respiration by consumers and decomposers, so subtracting RE from gross primary productivity gives NCP. Carbon accounting separates gross fixation from respiratory expenditure. Gross primary productivity records all photosynthetic carbon fixation; net primary productivity subtracts autotrophic respiration, while net community productivity subtracts total ecosystem respiration. Keeping flux
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 17
Total ecosystem respiration, RE, is the combined carbon dioxide release from autotrophic respiration, RA, and heterotrophic respiration, RH. Autotrophs respire to maintain and build plant, algal, or microbial tissues; heterotrophs—including animals, fungi, and many bacteria—respire while consuming living or dead organic matter. Adding these fluxes gives RE = RA + RH. Gross primary productivity removes CO2 from the atmosphere or water through carbon fixation, whereas ecosystem respiration returns CO2 through oxidation of organic carbon. Their difference defines net ecosystem production: NEP = G
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 17
Arthur George Tansley, a British ecologist, introduced the term “ecosystem” in 1935. He argued that ecologists should study organisms together with the physical factors of their environment as integrated systems, rather than treating the biological community in isolation. An ecosystem therefore includes the biotic community and abiotic surroundings, linked by energy flow, nutrient cycling, and feedback. Tansley’s formulation helped move ecology toward analysis of systems that can range from a pond or soil patch to a forest or the biosphere, depending on the boundaries selected. Charles Elton m
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 17
