RBSE SS Env Sci flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Ecosystem
- A functional unit in which biotic communities interact with their abiotic surroundings, exchanging energy and matter; examples include a pond, a desert grassland or the whole biosphere.
- Trophic level
- The position an organism occupies in a food chain, such as producer, primary consumer or secondary consumer; energy decreases at each higher level.
- Ecological pyramid
- A graphical representation of numbers, biomass or energy at successive trophic levels; the energy pyramid is always upright because energy is lost as heat.
- Ecotone
- A transition zone between two adjacent ecosystems, such as a grassland-desert boundary; it often supports higher species richness due to the edge effect.
- Soil profile
- A vertical section of soil showing horizons O, A, E, B, C and R; each horizon differs in organic matter, texture and mineral accumulation.
- Sheet erosion
- Uniform removal of a thin layer of topsoil by rainfall runoff over a slope; it is less visible than gully erosion but reduces fertility gradually.
- Rainwater harvesting
- Collection and storage of rain from rooftops or catchments for later use or groundwater recharge; Rajasthan examples include tanka, khadin and johad.
- Renewable resource
- A natural resource replenished by natural processes within a human timescale, such as solar energy, wind, biomass and fresh water under careful management.
- Biodiversity hotspot
- A region with exceptional endemic species and severe habitat loss; India contains parts of the Himalaya, Indo-Burma, Sundaland and Western Ghats hotspots.
- In-situ conservation
- Conservation of species within their natural habitat through protected areas, sacred groves and community reserves, allowing natural ecological processes to continue.
- Keystone species
- A species whose influence on ecosystem structure is disproportionate to its abundance; removing it causes major changes, as with tigers or fig trees.
- Ramsar site
- A wetland of international importance designated under the Ramsar Convention 1971; Rajasthan has Keoladeo Ghana and Sambhar Lake as designated sites.
- BOD
- Biochemical oxygen demand, the oxygen consumed by microorganisms decomposing organic matter in water; high BOD indicates organic pollution and low dissolved oxygen.
- Eutrophication
- Nutrient enrichment of water by nitrogen and phosphorus causing algal blooms, oxygen depletion and fish kills; human activity accelerates it as cultural eutrophication.
- Photochemical smog
- A brownish oxidising haze formed when nitrogen oxides and volatile organic compounds react in sunlight, producing ozone and peroxyacetyl nitrate; typical of Los Angeles.
- Noise zone standards
- Indian ambient noise limits in dB(A) for day and night: residential 55/45, commercial 65/55, industrial 75/70 and silence zone 50/40.
- Tragedy of the commons
- Overuse of a shared open-access resource because each user gains individually while costs are shared collectively; solutions include regulation and community ownership.
- Bishnoi movement
- The 1730 Khejarli sacrifice led by Amrita Devi Bishnoi to protect khejri trees from felling; it is an early Indian community conservation movement.
- Precautionary principle
- The rule that lack of full scientific certainty should not delay cost-effective measures to prevent serious or irreversible environmental harm.
- Demographic transition
- A model of population change from high birth and death rates through a phase of rapid growth to low birth and death rates as societies develop.
- Carrying capacity
- The maximum population an environment can support sustainably given available resources, technology and consumption patterns without degradation.
- Demographic dividend
- Economic growth potential arising when the working-age population is large relative to dependents; it requires education, skills and job creation to realise.
- Environmental Impact Assessment
- A structured process predicting environmental effects of a proposed project before approval, including scoping, baseline study, mitigation and public hearing.
- Circular economy
- An economic model that designs out waste and keeps materials in use through reuse, repair and recycling, replacing the linear take-make-dispose pattern.
- Sustainable Development Goals
- Seventeen global goals with 169 targets adopted in 2015 under the 2030 Agenda, covering poverty, water, energy, climate, biodiversity and institutions.
- Article 48A
- A Directive Principle added by the 42nd Amendment 1976 directing the State to protect and improve the environment and safeguard forests and wildlife.
- Polluter pays principle
- The principle that those who cause pollution bear the cost of preventing, controlling and remediating it, including compensation to affected communities.
- National Green Tribunal
- A specialised body created by the NGT Act 2010 to hear environmental civil cases speedily and order compensation or restitution for environmental damage.
- Quadrat method
- A sampling technique using a defined frame to record species and individuals; frequency is the percentage of quadrats containing a species.
- Secchi disc
- A circular white-black disc lowered into water to measure transparency; the depth at which it disappears estimates water clarity and turbidity.
- Sambhar Lake
- A large saline wetland in Rajasthan designated a Ramsar site, important for flamingos and salt production, threatened by reduced inflow and pollution.
- Biomagnification
- The increasing concentration of persistent pollutants such as DDT or mercury in organisms at successive trophic levels, raising exposure in top consumers.