Revision: 12th Std >> Biodiversity, Conservation and Environmental Issues MAH-MHT CET (PCM/PCB) Biodiversity, Conservation and Environmental Issues

It is a tool used to classify organisms based on their similarities and differences.

• The diversity of life forms present on Earth, including plants, animals, and microorganisms, is called biodiversity.
• Biodiversity is the occurrence of different types of genes among the individuals of species, habitats and ecosystems, both terrestrial and aquatic within a defined area.

Ramsar Sites: It is a wetland site designed of international importance under the Ramsar convention. It is an inter-governmental environmental treaty established in 1971 by UNESCO and coming into force in 1975.

Eutrophication: The process by which a body of water enriched in dissolved nutrients (such as phosphates) that stimulates the growth of aquatic algae usually resulting in the depletion of dissolved oxygen.

Hotspot is a biodegradable region that is both a significant reservoir of biodiversity and is threatened with destruction.

Biodiversity is defined as the variety of plant and animal life in the world or in a particular habitat, a high level of which is usually considered to be important and desirable

The sum total of species richness, i.e., the number of species of plants, animals and micro-organisms inhabiting in a given habitat, is known as biodiversity.

Species that completely disappear from the planet are referred to as extinct.

When a species possesses a very high risk of extinction as a result of rapid population decline of 50 to more than 70 per cent over the previous 10 years, it is said to be an endangered species.

Species that are not native to a region or locality but are unintentionally or purposefully introduced and cause harm to the native species already present are referred to as invasive species.

Cryopreservation is a technique in which organisms, tissue, and cells are preserved and stored at the very low temperature of liquid nitrogen (−196°C) for years. They remain viable in the frozen state for future use.

Pollution is undesirable change in physical, chemical and biological characteristics of environmental components.

Air pollution means degradation of the air quality which harmfully affects the living organisms as well as certain objects.

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Contamination of air by harmful substances like poisonous gases, smoke, particulate matter, microbes, etc., is called air pollution.

Noise is defined as any unpleasant/loud undesired sound interfering with one's hearing and concentration and the pollution caused due to noise is termed as noise pollution.

Noise is defined as any unpleasant, loud, undesired sound that interferes with one’s hearing and concentration, and the pollution caused by noise is termed noise pollution.

Oil spills are the accidental discharges of petroleum into oceans or estuaries. The sources of spills are overturned oil tankers, offshore oil mining, and oil refineries.

Water pollution means any change in the water quality which makes it unsuitable for use by humans and by other living organisms.

The amount of heat that is needed to raise the temperature of a unit mass of a substance by 1°C is called specific heat capacity.

The heating-up of the earth’s atmosphere due to trapped infrared rays reflected from the earth's surface by atmospheric gases is called the greenhouse effect.

The warming up of the atmosphere due to trapping of the solar radiation reflected by the earth by gases like carbon dioxide is called Greenhouse effect.

The gradual increase in the average surface temperature of the Earth due to rising concentrations of greenhouse gases in the atmosphere is called global warming.

The gradual increase in Earth’s average surface temperature due to rising concentrations of greenhouse gases in the atmosphere is called global warming.

Deforestation is the conversion of forested areas into non-forested areas for agricultural, industrial, urban or other human uses.

• Biodiversity is the variety of life on Earth — including microorganisms, fungi, plants and animals in both terrestrial and aquatic habitats.
• Diversity exists in size, shape, colour, nutrition, habitat and reproduction. It arises due to adaptations of organisms to different environmental conditions for survival.
• Biodiversity = totality of genes, species and ecosystems in a region (as per IUCN, UNEP and WRI).
• Term coined by Walter Rosen (1982), popularised by Edward Wilson to describe diversity at all levels of biological organisation.
• Today's biodiversity is the result of 3.5 billion years of evolutionary history, influenced by natural processes and human activities.

• Biodiversity exists at three levels — genetic, species and ecological (ecosystem) diversity.
• Genetic diversity (intraspecific) is variation in genes and chromosomes within the same species. Example: 1000 varieties of mangoes and 50,000 varieties of rice in India.
• Species diversity (interspecific) refers to the variety of plant and animal species (richness) and the number of individuals of each species (evenness) in a region. Example: India is among the 15 nations richest in species diversity.
• Ecological diversity refers to the variety of ecosystems and habitats within a geographical area. Example: India has deserts, rainforests, wetlands, grasslands, estuaries, etc.
• Diversity at all three levels is rapidly being reduced by modern human activities.

Latitudinal Gradient

• Species richness is high near the equator (tropics: 23.5°N to 23.5°S) and decreases towards the poles. Example: The Amazon rainforest has 40,000 plants, 1300 birds and 427 mammals.
• Tropics have high diversity due to a stable climate, less glaciation, abundant sunlight, higher rainfall and greater niche specialisation.

Altitudinal Gradient

• Species diversity decreases at higher altitudes due to drastic climatic changes and seasonal variations.

Species-Area Relationship

• Observed by Alexander Von Humboldt, species richness increases with area but only up to a limit. For many species, this forms a rectangular hyperbola.
• Expressed as: log⁡ S = log⁡ C + Z log⁡ A, where S = species richness, A = area, Z = slope, C = Y-intercept. On a logarithmic scale, it gives a straight line.
• Z value for smaller areas = 0.1 to 0.2. For larger areas (continents) = 0.6 to 1.2 (steeper slope — species increase faster than area explored).

• A stable community maintains constant biomass production, withstands disturbances, recovers quickly and resists invasive species.
• David Tilman proved that greater species richness maintains the stability of an ecological community. Rich diversity leads to lesser variation in biomass production — called Productivity Stability Hypothesis.
• Paul Ehrlich (Stanford) proposed the Rivet Popper Hypothesis — an ecosystem compared to an aeroplane and species to rivets. Loss of one species may not cause immediate damage, but gradual loss seriously threatens the ecosystem.
• Loss of key species causes rapid and serious damage, showing that diversity and ecosystem well-being do not share a linear relationship.
• Loss of species disturbs food chains, food webs, energy flow and natural cycles — affecting the entire balance of the ecosystem.

• Over 1.5 million species documented so far. Robert May estimated about 7 million species globally.
• More than 70% of recorded species are animals, plants comprise only 22%, and 70% of all animals are insects.
• Fungi species outnumber all vertebrates combined. Conventional taxonomic methods cannot identify prokaryotic species.
• India is one of 12 megadiverse nations, holding 8.1% of global biodiversity with only 2.4% of the world's land area. About 45,000 plant species and nearly double the number of animal species have been recorded.
• India has over 1,00,000 plant and 3,00,000 animal species yet to be discovered. Only 22% of India's natural wealth has been recorded so far.
• Tropical rainforests are still unexplored. The major threat is species loss due to deforestation and reclamation before they are even identified.
• A lizard from Amboli Ghat, Maharashtra, misidentified as Hemidactylus brookii, was correctly renamed Hemidactylus varadgirii using DNA profiling, in honour of Dr. Varad Giri.

• Loss of biodiversity causes ecosystem imbalance and may lead to extinction of species (natural, mass, and anthropogenic).
• Natural causes include forest fires, earthquakes, and volcanic eruptions, while human causes include habitat destruction, hunting, and overexploitation.
• The present biodiversity loss is considered the 7th mass extinction, occurring 100–1000 times faster due to human activities.
• Loss of biodiversity reduces plant productivity, disturbs environmental processes, and lowers resistance to disturbances.
• The “Evil Quartet” causes biodiversity loss: habitat loss, over-exploitation, alien species invasion, and co-extinction.
• Invasive species can harm or eliminate native species due to a lack of natural predators (e.g., Parthenium, water hyacinth).
• Conservation status is maintained in the IUCN Red Data Book; endangered species have declining populations, while extinct species are completely lost.

• Conservation of biodiversity means protection and proper management of species to maintain balance and ensure benefits for the present and the future.
• Narrowly utilitarian value: biodiversity provides food, shelter, medicines, and industrial products; many species are used in traditional and modern medicine.
• Broadly utilitarian value: biodiversity supports ecological processes like oxygen production, pollination, seed dispersal, and also provides recreational benefits.
• Bioprospecting involves searching for useful biological resources like new medicines, genes, and economically important products.
• Ethical reason: all living organisms have an equal right to live, so humans should not destroy biodiversity.

• India became a party to the Convention on Biological Diversity (CBD, 1992) and passed the Biological Diversity Act in 2002 in compliance with it.
• Main objectives - regulation of access to Indian biological resources and cataloguing of traditional knowledge about ethnobiological materials.
• Three-tier system - NBA (national level), SBBs (state level), BMCs (local level). Permission from the NBA is mandatory before exploiting any biological resource.
• Violation of NBA approval can lead to jail and a fine of up to ₹10 lakh. The NBA has the powers of a civil court.
• Rahibai Popere ("Seed Mother of Maharashtra") maintains a seed bank of 54 crops and 116 varieties. Awarded Padma Shri in 2020 and featured in BBC's '100 Women 2018'.

• Exponential population growth and rapid industrialisation over the last ten decades have disturbed the balance between living and non-living components of the biosphere, leading to severe pollution.
• Pollution is an undesirable change in the physical, chemical and biological characteristics of environmental components.
• A pollutant is any chemical substance or form of energy that adversely affects the health of living organisms, including humans.
• The government of India passed the Environment Protection Act, 1986, to protect and improve the quality of the environment.

• Air pollutants are of two types - particulate (smoke, smog, dust, heavy metals) and gaseous (CO₂, CO, SO₂, NO, NO₂). PM2.5 particles cause the greatest harm, penetrating deep into the lungs, causing irritation and breathing disorders.
• NO₂ + water vapour = nitric acid, causing irritation to eyes, lungs, liver and kidneys. CO is a poisonous gas produced by the incomplete combustion of fuel.
• Three control mechanisms - Electrostatic Precipitator (removes 99% soot/dust from industrial exhaust), Exhaust Gas Scrubber (removes SO₂ using lime/water spray), Catalytic Converter (removes poisonous gases from automobile exhaust; requires unleaded petrol).
• Delhi was 4th most polluted city in 1990. Following Supreme Court orders, all city buses were converted to CNG by 2002 — economic, efficient and adulteration-proof.
• India adopted BS-VI emission standards in 2018, skipping BS-V, reducing CO₂ and SO₂ levels in Delhi.

1. Control at Source: Air pollution can be reduced by proper planning and siting of industries, improved design of equipment, correct fuel–air mixture, use of fuel additives, and efficient engine design in vehicles.
2. Vehicular Pollution Control: Installation of catalytic converters, use of unleaded petrol, adoption of CNG/LPG, and enforcement of Bharat Stage (Euro) emission norms significantly reduce harmful exhaust emissions.
3. Industrial Pollution Control Devices: Emissions from industries and power plants are controlled using cyclone collectors, scrubbers, and electrostatic precipitators, which remove particulate matter and harmful gases before release into the atmosphere.
4. Legislative and Policy Measures: Laws such as the Air (Prevention and Control of Pollution) Act, 1981 and Environment (Protection) Act, 1986, along with emission standards and fuel regulations, play a crucial role in controlling air pollution.
5. Afforestation and Public Awareness: Planting pollution-tolerant trees around urban and industrial areas, along with environmental education and public awareness programmes, helps improve air quality and reduce pollution impacts.

• Noise pollution is an undesirable high level of sound. Included as an air pollutant under Air (Prevention and Control of Pollution) Act, 1981, amended in 1987.
• Sources - machines, transportation, construction sites, industries, festivals and public functions.
• Exposure to 150 dB or more causes permanent hearing loss. Other effects - sleeplessness, increased heartbeat, altered breathing, psychological stress and negative impact on the child's learning.
• Control measures - sound absorbent materials, muffling noise, and horn-free zones near schools and hospitals.
• Supreme Court banned loudspeakers at public gatherings after 10 pm. The government has rules against firecrackers and loudspeakers.

• The Water (Prevention and Control of Pollution) Act, 1974, was passed to safeguard water resources. Main sources — domestic sewage, industrial effluents and agricultural run-off.
• BOD (Biochemical Oxygen Demand) is the dissolved oxygen required by microorganisms to decompose organic matter in water. High BOD = high pollution = low oxygen = death of aquatic organisms.
• Algal bloom — excessive growth of planktonic algae due to excess nitrogen and phosphorus. Releases toxins and causes fish mortality. Water hyacinth (Eichhornia crassipes) — "Terror of Bengal" — is an invasive plant that chokes water bodies.
• Eutrophication — natural ageing of a lake by nutrient enrichment. When accelerated by human activities, it is called Cultural/Accelerated Eutrophication, depleting oxygen and killing aquatic life.
• Biomagnification — increase in concentration of toxic pollutants (DDT, mercury) at successive trophic levels. Non-degradable, accumulate in tissues and pass to the next trophic level.
• Thermal pollution — caused by thermal and nuclear power plants releasing hot coolant water, raising water temperature and killing aquatic flora and fauna.

• Proper maintenance of water bodies and avoiding the disposal of waste into them helps reduce sewage pollution.
• Use of pesticides and chemical fertilisers should be minimised to prevent water contamination.
• Sewage should be properly treated before being released into rivers and other water bodies.
• Ecological sanitation (Ecosan) uses dry composting toilets to recycle human waste into organic manure, reducing the need for fertilisers.
• Ecosan toilets save water, prevent groundwater contamination, and are useful in water-scarce areas.
• Recycling of sewage water using reverse osmosis (RO) helps solve water scarcity and waste disposal problems.
• Rainwater harvesting and sewage recycling in cities help conserve water and reduce sewage generation.

• The greenhouse effect is a naturally occurring phenomenon that heats Earth's surface. Without it, Earth's temperature would be -18°C instead of 15°C.
• Greenhouse gases are transparent to solar radiation but retain and reflect back long-wave heat radiation. Main gases — CO₂ (60%), CH₄ (20%), CFCs (14%), N₂O (6%).
• Earth's surface re-emits heat as infrared radiation. Greenhouse gases like CO₂ and CH₄ absorb this and return heat to Earth's surface — causing the greenhouse effect.
• Rising CO₂ due to the burning of fossil fuels and deforestation intensifies the greenhouse effect, causing global warming.
• Global warming leads to melting of polar ice, rising sea levels, changes in rainfall patterns and loss of biodiversity.

• Global warming — rise in Earth's temperature due to increased greenhouse gases. Earth's temperature rose by 0.6°C in the past century, mostly in the last three decades.
• Causes odd climatic changes like the El Niño effect, melting of polar ice caps and Himalayan snow caps, and submergence of coastal areas.
• Chewang Norphel ("Ice Man of India"), a civil engineer from Ladakh, built 13 artificial glaciers to combat global warming, increasing groundwater recharge and providing irrigation water.
• Artificial glaciers are built at lower elevations so they melt earlier, expanding the growing season.
• Control measures — reduce fossil fuel use, improve energy efficiency, reduce deforestation, plant trees and control population growth.

• Ozone layer — present in the stratosphere (12–15 km above Earth). Absorbs harmful UV radiation. Thickness measured in Dobson Units (DU).
• CFCs rise to the stratosphere → UV rays release Cl atoms → Cl acts as a catalyst → continuously degrades O₃ → forms ozone hole, particularly over the Antarctic region.
• Other ozone-depleting substances — SO₂, nitrogen oxides and methyl chloroform.
• UV-B (280–322 nm) — damages DNA, causes mutations, skin cancer, ageing and snow blindness/cataract. It can permanently damage the cornea.
• The Montreal Protocol was signed at Montreal, Canada, in 1987 (effective 1989) to control the emission of ozone-depleting substances.

• India's forest cover reduced from 30% to 19.4% in the 20th century. National Forest Policy 1988 recommends 33% for plains, 67% for hills.
• Effects of deforestation — increased CO₂, loss of biodiversity, disturbed hydrological cycle, soil erosion and desertification.
• Jhum Cultivation (Slash and Burn) — trees cut and burnt, ash used as fertiliser, land farmed, then left to recover. Practised in North-East India.
• Chipko Movement — launched by Chandi Prasad Bhatt and Sundar Lal Bahuguna against tree felling by timber contractors in Uttarakhand.
• Amrita Devi Bishnoi Wildlife Protection Award — given to individuals/communities showing courage in protecting wildlife. Inspired by Amrita Devi, who sacrificed her life in 1731 to protect trees in Rajasthan.
• Joint Forest Management (JFM) — introduced in the 1980s; local communities protect forests and get forest products (fruits, gum, rubber, medicine) in return.

• Mission Harit Maharashtra - launched in 2016 by the Government of Maharashtra to plant 50 crore trees in 4 years (2016–2019), in line with NFP's 33% forest cover target.
• Plantation count - 2016: 2.87 crore, 2017: 5.17 crore, 2018: 15.17 crore, 2019 target: 33 crore (launched at Anandwan, Warora).
• The Japanese Miyawaki method of plantation was adopted. Pilot programmes run in Beed, Hingoli, Pune, Jalgaon and Aurangabad.
• Helpline 1926 ('Hello Forest') - 24-hour toll-free number for plantation info and mass awareness.
• Mobile app 'My Plants' - records plantation details like numbers, species and location.