Licchavi Lyceum


Licchavi Lyceum


I. Environment and Ecosystem

II. Biodiversity and its Conservation

III. Ecosystems

IV. Natural Resources

V. Environmental Pollution

VI. Climate Change

VII. Ozone Depletion

VIII. Waste Management

IX. Social Issues and the Environment

X. Environment Impact Assessment (EIA)

XI. International Organisation and forum for Environment Conservation
XII. Organisation in India for Environment Conservation

XII. Species under Threat

Environment Short Note

Things that surround us including living or nonliving things makes the Environment. It includes physical, chemical and other natural forces. Living things live in their environment. They constantly interact with it and adapt themselves to conditions in their environment. All organisms (from virus to man) are obligatorily dependent on the environment for food, energy, water, oxygen, shelter and for other needs.

The relationship and interaction between organism and environment are highly complex. No organism can live alone without interacting with other organisms. So each organism has other organisms as a part of its environment. Each and everything with which we interact or which we need for our sustenance forms our environment.


Ecology is the branch of biology that deals with the study of interactions between organisms and their environment.

It deals with the ways in which organisms are moulded by their environment, how they make use of environmental resources including energy flow and mineral cycling.

The branch of ecology is divided into Autecology, Synecology and habitat ecology.

Autecology, also called Species Ecology, the study of the interactions of an individual organism or a single species with the living and nonliving factors of its environment.

Synecology is the study of group of organisms of different species which are associated together as a unit in form of a community. It is also known as community ecology.

Habitat Ecology: It is where the species will attempt to be as adaptive as possible. Habitats may be an open geographical area or a specific site

1. Organisms: (individual) basic unit of study. This is the first and basic unit of classification.
2. Population: ‘Population’ is defined as a group of freely interbreeding individuals of the same species present in a specific area at a given time.
3. Community: A group of organisms consisting of a number of different species that live in an area and interact with each other.
4. Ecosystem: A communities of organisms and their physical environment, interacting as an ecological unit.
Study of the community in relation to the structure of its ecosystem-nutrients cycling, climate, energy flow etc.
5. Biome: A large community unit, characterized by a major vegetation type and associated fauna, found in a specific climatic region is a biome. Biomes refer basically to terrestrial areas.
It is a large regional unit characterised by a major vegetation type and associated fauna found in a specific climatic zone.

It is the zone of junction between two or more distinct ecosystems, like mangrove is the ecotone between two ecosystems one terrestrial and other marine. An ecotone may consist of entirely different species found neither in adjoining ecosystems.

At times the biodiversity in the Ecotone is higher than adjoining ecosystem. The tendency of increased variety and density of some organisms at the community border is known as edge effect.

A niche is the set of all the factors that a particular species required in order to survive in an ecosystem.

A habitat can contain many ecological niches and support a variety of species. The ecological niche of an organism represents the range of conditions that it can tolerate, the resources it utilizes, and its functional role in the ecological system. Each species has a distinct niche, and no two species are believed to occupy exactly the same niche.

Every ecosystem has two components, namely, biotic components and abiotic components. Biotic components refer to all living organisms in ecology while abiotic refer to the non-living things. These biotic and abiotic interactions maintain the equilibrium in the environment.

  1. Abiotic Substances: These include basic inorganic and organic compounds of the environment or habitat of the organism. The inorganic components of an ecosystem are carbon dioxide, water, nitrogen, calcium, phosphate, all of which are involved in matter cycles (biogeochemical cycles).
  2. Biotic factors are the living components present in an ecosystem. More specifically, it includes all flora and fauna.

Wide variety of Services are provided by the Ecosystem. It includes: 

  • Provision of food, fuel and fiber
  • Provision of shelter and building materials
  • Purification of air and water
  • Detoxification and decomposition of wastes
  • Stabilization and moderation of the Earth’s climate
  • Moderation of floods, droughts, temperature
  • extremes and the forces of wind.
  • Generation and renewal of soil fertility, including nutrient cycling.
  • Pollination of plants, including many crops
  • Control of pests and diseases
  • Maintenance of genetic resources as key inputs to crop varieties and livestock breeds, medicines, and other products Cultural and aesthetic benefits

The function of an ecosystem is abroad, vast and complete dynamic system. It can be studied under Energy flow, 
Nutrient cycling and Ecological succession. 

Energy is the basic force responsible for all metabolic activities. The flow of energy from producer to top consumers is called energy flow which is unidirectional. The study of Trophic level interaction in an ecosystem gives an idea about the energy flow through the ecosystem.

Primary Producers: Plants and algae comprise the lowest level of the trophic system called primary producers or autotrophs.

They create their own food using photosynthesis. By using energy gleaned from the sun and nutrients gathered from the soil or water.

Therefore, plants and algae are the primary producers of energy and don’t need to consume food from other sources. They can be either terrestrial or aquatic.

Primary Consumers: Herbivores belong in the second level of the trophic system. Called primary consumers, herbivores eat only plants and algae as their sources of energy. Herbivores cannot manufacture their own food. Common herbivores include: most insects, rabbits, cows, antelopes etc. 

In an ocean ecosystem, animals such as zoo plankton or krill that consume algae belong to the second level. Primary consumers use the energy naturally created by plants to function.

Secondary Consumers: A specialized type of carnivore belongs to the third level of the trophic system. Carnivores are organisms that prey on and eat other animals. Animals that consume only herbivores belong to Level 3 and are referred to as secondary consumers. This type of carnivore uses the energy the primary consumer gathered from the plants it ate. Animals such as foxes, which primarily eat rabbits, are as secondary consumers. Even animals such as fish, rats, spiders and ants can be secondary consumers.

Tertiary Consumers: The fourth trophic level includes carnivores and omnivores which eat the animals that belong to the third level. Omnivores are animals that eat both plants and animals. Omnivores consume both primary producers and secondary consumers. Animals on this level are called tertiary consumers. These animals tend to receive less energy from their food than animals in the third level. This is because the energy created by primary producers has been transferred and converted at least twice by animals in the previous groups. Each time you go up a trophic level, available energy is reduced.

Apex Predators: The fifth trophic level is the final level in an ecosystem. It is composed of apex predators that prey on and eat the carnivores and herbivores in the fourth level. Apex predators are at the top of the food chain and have no predators of their own. They allow each different trophic level to sustain stable levels of animals. Lions, alligators, bears, anacondas, killer whales and hawks are common apex predators.

Organisms in the ecosystem are related to each other through feeding mechanism or trophic levels, i.e. one organism becomes food for the other. A sequence of organisms that feed on one another, form a food chain. 

A food chain starts with producers and ends with top carnivores. The sequence of eaten and being eaten, produces transfer of food energy and it is known as food chain. The plant converts solar energy into protoplasm by
photosynthesis. Small herbivores consume the vegetable matter and convert them into animal matter. These herbivores are eaten by large carnivores.

A food chain represents only one part of the food or energy flow through an ecosystem and implies a simple, isolated relationship, which seldom occurs in the ecosystems. An ecosystem may consist of several interrelated food chains. More typically, the same food resource is part of more than one chain, especially when that resource is at the lower trophic levels.  A food web illustrates, all possible transfers of energy and nutrients among the organisms in an
ecosystem, whereas a food chain traces only one pathway of the food.

An ecological pyramid is a graphical representation showing the relationship between different organisms in an ecosystem. The food producer forms the base of the pyramid and the top carnivore forms the tip. Other consumer trophic levels are in between. 

Pyramid of Ecology
Pyramid of Ecology


The pyramid consists of a number of horizontal bars depicting specific trophic levels which are arranged sequentially from primary producer level through herbivore, carnivore onwards. The length of each bar represents the total number of individuals at each trophic level in an ecosystem.

The number, biomass and energy of organisms gradually decrease with each step from the producer level to the consumer level and the diagrammatic representation assumes a pyramid shape.

The ecological pyramids are of three categories.
1. Pyramid of numbers,
2. Pyramid of biomass, and
3. Pyramid of energy or productivity.

This deals with the relationship between the numbers of primary producers and consumers of different levels. It is a graphic representation of the total number of individuals of different species, belonging to each trophic level in an ecosystem.

Depending upon the size and biomass, the pyramid of numbers may not always be upright, and may even be completely inverted. 

(a) Pyramid of numbers (upright) – In this pyramid, the number of individuals is decreased from lower level to higher trophic level. This type of pyramid can be seen in grassland ecosystem.

Pyramid of Numbers
Pyramid of Numbers

The grasses occupy the lowest trophic level (base) because of their abundance.

(b) Pyramid of numbers (inverted): In this pyramid, the number of individuals is increased from lower level to higher trophic level.


For Example, a forest would have a small number of big trees (primary producers) making the base of  pyramid.  Further, the dependent herbivores (Example – Birds) in the next higher trophic level and it is followed by parasites in the next trophic level. Hyper parasites being at higher trophic level represents higher in number and the resulting pyramid is in inverted shape. 

A pyramid of numbers does not take into account the fact that the size of organisms being counted in each trophic level can vary.

(c) Pyramid of Biomass (upright)

  • For most ecosystems on land, the pyramid of biomass has a large base of primary producers with a smaller trophic level perched on top.
  • The biomass of producers (autotrophs) is at the maximum. The biomass of next trophic level i.e. primary consumers is less than the producers. The biomass of next higher trophic level i.e. secondary consumers is less than the primary consumers. The top, high trophic level has very less amount of biomass.

(d) Pyramid of Biomass  (Inverted):

  • In contrast, in many aquatic ecosystems, the pyramid of biomass may assume an inverted form. (In contrast, a pyramid of numbers for the aquatic ecosystem is upright)
  • This is because the producers are tiny phytoplankton that grows and reproduces rapidly.
  • Here, the pyramid of biomass has a small base, with the consumer biomass at any instant exceeding the producer biomass and the pyramid assumes an inverted shape.

Pyramid of Energy: 

(c) Pyramid of Biomass (upright)

  • For most ecosystems on land, the pyramid of biomass has a large base of primary producers with a smaller trophic level perched on top.
  • The biomass of producers (autotrophs) is at the maximum. The biomass of next trophic level i.e. primary consumers is less than the producers. The biomass of next higher trophic level i.e. secondary consumers is less than the primary consumers. The top, high trophic level has very less amount of biomass.

(d) Pyramid of Biomass  (Inverted)

  • In contrast, in many aquatic ecosystems, the pyramid of biomass may assume an inverted form. (In contrast, a pyramid of numbers for the aquatic ecosystem is upright)
  • This is because the producers are tiny phytoplankton that grows and reproduces rapidly.
  • Here, the pyramid of biomass has a small base, with the consumer biomass at any instant exceeding the producer biomass and the pyramid assumes an inverted shape.

It shows the functional role of species in an ecosystem. An energy pyramid, reflects the laws of thermodynamics, with conversion of solar energy to chemical energy and heat energy at each trophic level and with loss pf energy being depicted at each transfer to another trophic level. Hence the pyramid is always upward, with large energy base at the bottom.

Pyramid of Energy
Pyramid of Energy

Let us explain this with an example. Suppose an ecosystem receives 1000 calories of light energy in a given day. Most of the energy is not absorbed; some is reflected back to space; of the energy absorbed only a small portion is utilized by green plants out of which the plant uses up some for respiration and of the 1000 calories, therefore only 100 calories are stored as energy rich materials. 

Now suppose an animal, say a deer, eats the plant containing 100 calories of food energy. The deer uses some of
it for its own metabolism and stores only 10 calories as food energy. Further, a lion that eats the deer gets an even smaller amount of energy. Thus usable energy decreases from sunlight to producer to herbivore to carnivore.

Therefore, the energy pyramid will always be uprightEnergy pyramid concept helps to explain the phenomenon of biological magnification, the tendency for toxic substances to increase in concentration progressively at higher levels of the food chain.

Toggle Content
Toggle Content

Pollutants and Trophic Level

Pollutants pass through an ecosystem’s trophic levels. Non-degradable pollutants (persistent pollutants), which cannot be broken down by detrivores, not only migrate through the trophic levels but also stay there for a long time.

The example of non-degradable pollutant material, i.e. which cannot be metabolized by the living organisms is chlorinated hydrocarbons.

The process of accumulation of pollutant (Heavy Metals) from environment to first organism.  It refers to how pollutants enter a food chain.

The tendency of pollutants to get magnified as it moves from one trophic level to other. Thus in biomagnification there is an increase in concentration of a pollutant from one link in a food chain to another.


Biotic Interaction

The interactions between populations of species in a community are broadly categorized into positive (beneficial) and negative (inhibition) interactions, depending upon the nature of effect on the interacting organisms.

Both species gets benefitted. Example: in pollination mutualisms, the pollinator gets food (pollen, nectar), and the plant has its pollen transferred to other flowers for cross-fertilization (reproduction).

One species benefits, the other is unaffected. Example: cow dung provides food and shelter to dung beetles. The beetles have no effect on the cows.

Both species are harmed by the interaction. Example: if two species eat the same food, and there isn’t enough for both, both may have access to less food than they would if alone. They both suffer a shortage of food. 

One species benefits, the other is harmed. Example : predation-one fish kills and eats parasitism: tick gains benefit by sucking blood; host is harmed by losing blood.

One species is harmed, the other is unaffected. Example: A large tree shades a small plant, retarding the growth of the small plant. The small plant has no effect on the large tree.

There is no net benefit or harm to either species. 

Neutralism is also sometimes described as the, relationship between two species inhabiting the same space and using the same resources, but that have no effect on each other.

Nutrient Cycling

The nutrient cycle is a concept that describes how nutrients move from the physical environment to the living organisms, and subsequently recycled back to the physical environment. This movement of nutrients from the  environment into plants and animals and again back to the environment is essential for life and it is the vital function of the ecology of any region. 

In any particular environment, to maintain its organism in a sustained manner, the nutrient cycle must be kept balanced and stable.

Nutrient cycles are of two types, the gaseous and the sedimentary.

Gaseous Cycles: (a) Water Cycle (Hydrologic), (b) The Carbon Cycle, (c) The Nitrogen Cycle

Sedimentary Cycle: (a) Phosphorus Cycle, (b) Sulphur Cycle

It is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere, terrestrial, and marine ecosystems.

The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification.

The majority of Earth’s atmosphere (78%) is atmosphere nitrogen, making it the largest source of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems.

The nitrogen cycle is of particular interest to ecologists because nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition. Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global nitrogen cycle.

Agents of Nitrogen Fixation: Nitrogen fixation in terrestrial ecosystems is predominantly carried out by symbiotic microbes, whereas bulk of fixation in aquatic ecosystems is done by free-living microbes.

The nitrogen cycle contains several stages.

Nitrogen fixation: Atmospheric nitrogen is converted into the usable form by lightning strikes or symbiotic bacteria, which are known as Diazotrophs. These bacteria consist of a nitrogenase enzyme, which has the capability to combine gaseous nitrogen with hydrogen to form ammonia.

Ammonification: When plants or animal die organic nitrogen is again released back into the soil. Bacteria or fungi present in the soil convert them back into ammonium. This process is also called as mineralization.

Assimilation: Primary producers take in this gas from the soil with the help of their roots in the form of amino acids, nitrite ions, nitrate ions or ammonium ions. This way it enters the food cycle when the consumers eat the plants.

Nitrification: In this process, the ammonia is converted into nitrate by the presence of bacteria in the soil. Nitrites are formed by the oxidation of Ammonia with the help of Nitrosomonas bacterium species. Later, the produced nitrites are converted into nitrates by Nitrobacter. This conversion is very important as ammonia gas is toxic for plants.

Denitrification: Nitrogen makes its way back into the atmosphere through a process called denitrification, in which nitrate (NO3-) is converted back to gaseous nitrogen (N2).

Nitrogen Cycle
Nitrogen Cycle

The hydrologic cycle is the continuous circulation of water in the Earth atmosphere system which is driven by solar energy. Water on our planet is stored in major reservoirs like atmosphere, oceans, lakes, rivers, soils, glaciers, snowfields, and groundwater. 

Water moves from one reservoir to another by the processes of evaporation, transpiration, condensation, precipitation, deposition, runoff, infiltration, and groundwater flow.

Water Cycle
Water Cycle

Carbon is present in the atmosphere, mainly in the form of carbon dioxide (C02). Carbon cycle involves a continuous exchange of carbon between the atmosphere and organisms. Carbon from the atmosphere moves to green plants by the process of photosynthesis, and then to animals. By process of respiration and decomposition of dead organic matter it returns back to atmosphere. It is usually a short term cycle.

Some carbon also enters a long term cycle. It accumulates as undecomposed organic matter in the peaty layers of marshy soil or as insoluble carbonates in bottom sediments of aquatic systems which take a long time to be released.
In deep oceans such carbon can remained buried for millions of years till geological movement may lift these rocks above sea level. These rocks may be exposed to erosion, releasing their carbon dioxide, carbonates and bicarbonates into streams and rivets.

Fossil fuels  such as coals, oil and natural gas etc. are organic compounds that were buried before they could be decomposed and were subsequently transformed by time and geological processes into fossil fuels. When they are burned the carbon stored in them is released back into the atmosphere as carbon-dioxide.

Carbon Cycle
Carbon Cycle

Phosphorus plays a central role in aquatic ecosystems and water quality. Unlike carbon and nitrogen, which come primarily from the atmosphere, phosphorus occurs in large amounts as a mineral in phosphate rocks and enters the cycle from erosion and mining activities. This is the nutrient considered to be the main cause of excessive growth of rooted and free-floating microscopic plants in lakes.

The main storage for phosphorus is in the earth’s crust. On land phosphorus is usually found in the form of phosphates. By the process of weathering and erosion phosphates enter rivers and streams that transport them to the ocean. 

In the ocean once the phosphorus accumulates on continental shelves in the form of insoluble deposits. After millions of years, the crustal plates rise from the sea floor and expose the phosphates on land. After more time, weathering will release them from rock and the cycle’s geochemical phase begins again.

Phosphorous Cycle
Phosphorous Cycle

The sulphur reservoir is in the soil and sediments where it is locked in organic {coal, oil and peat) and inorganic deposits (pyrite rock and sulphur rock) in the form of Sulphates, Sulphides and organic sulphur. 

It is released by weathering of rocks, erosional runoff and decomposition of organic matter and is carried to terrestrial and aquatic ecosystems in salt solution. 

The sulphur cycle is mostly sedimentary except two of its compounds hydrogen sulphide and sulphur dioxide add a gaseous component to its normal sedimentary cycle. 

Sulphur enters the atmosphere from several sources like volcanic eruptions, combustion of fossil fuels, from surface of ocean and from gases released by decomposition. Atmospheric hydrogen sulphide also gets oxidised into sulphur dioxide. Atmospheric sulphur dioxide is carried back to the earth after being dissolved in rainwater as weak sulphuric acid.


Sulfur Cycle
Sulfur Cycle


Ecological succession is the process of change in the species structure of an ecological community over time. The time scale can be decades (for example, after a wildfire), or even millions of years after a mass extinction.

The community begins with relatively few pioneering plants and animals and develops through increasing complexity until it becomes stable or self-perpetuating as a climax community. The “engine” of succession, the cause of ecosystem change, is the impact of established species upon their own environments. A consequence of living is the sometimes subtle and sometimes overt alteration of one’s own environment.

The plants that invade the bare land initially are called pioneer species. The assemblage of pioneer species forms the pioneer community. Generally, the pioneer species show high rate of growth but short life span. In time, the pioneer community is replaced by another community with different species combination. This second community is replaced by a third community, and so on.

Succession occurring on previously unoccupied sites, such as a rock outcrop or glacial moraine, is called primary succession.

In primary succession on rocks these are usually lichens which are able to secrete acids to dissolve rock, helping in weathering and soil formation. These later pave ways to some very small plants like bryophytes, which are able to take hold in the small amount of soil. They are, with time, succeeded by bigger plants, and after several more stages, ultimately a stable climax forest community is formed. The climax community remains stable as long as the environment remains unchanged.

The more common type of succession is the secondary succession, which occurs in an area where the natural vegetation has been destroyed or removed. For example, the forests destroyed by fire and excessive lumbering may be preoccupied by herbs in the initial stages. The reappearance and establishment of communities in such areas is called secondary succession.

The terminal stage of succession is represented by the climax community. The climax community is stable and does not show changes in species composition, as long as the environmental conditions remain the same.

Note: Hydrarch succession takes place in wetter areas and Xerarch succession takes place in dry areas.

Succession of micro-organisms including fungi and bacteria occurring within a microhabitat is known as micro-succession or serule. This type of succession occurs in recently disturbed communities or newly available habitat, for example in recently dead trees, animal droppings, exposed glacial till, etc.

During retrogressive succession, vegetation shifts from taller forests with higher species richness to shorter woody communities of lower diversity. Studies of soil chrono-sequences have emphasized the role of phosphorus (P) depletion in driving these changes in community structure and composition, but neglected the possible role of poor drainage which is often associated with the oldest sites.

When succession is brought about by the living inhabitants of that community itself, the process is called autogenic succession. On the other hand, if the changes are brought by the outside agents, it is called the allogenic succession. 

Succession in which, initially the green plants are much greater is quantity is known as autotrophic succession; and the ones in which the heterotrophs are greater in quantity is known as heterotrophic succession.

Terrestrial Ecosystems

Due to varied climate, the plant and animal life existing in different terrestrial areas vary which result in differentiation
of ecosystem as segments within the large biosphere. The most important limiting factors of the terrestrial ecosystems are moisture and temperature.

The word tundra means a “barren land” since they are found where environmental conditions are very severe. There are two types of tundra: arctic and alpine.

The northernmost region on earth surrounding the ice cap. It has very small biodiversity

Arctic tundra extends as a continuous belt below the polar ice cap and above the tree line in the northern hemisphere. It occupies the northern fringe of Canada, Alaska, European Russia, Siberia and island group of Arctic Ocean. On the south pole, tundra is very small since most of it is covered by ocean. Alpine tundra occurs at high mountains above the tree line.

Cold regions with high rainfall, strong seasonal climates with long winters and short summers are characterised by boreal coniferous forest. This is characterised by evergreen plant species such as Spruce, fir and pine trees, etc. and by animals such as the lynx, wolf, bear etc. 

Boreal forest soils are not rich in nutrients. The litter derived from conifer needle leaf is decomposed very slowly. These soils are acidic. The productivity and community stability of a boreal forest are lower than those of any other forest ecosystem.

The temperate forests are characterised by a moderate climate and broad-leafed deciduous trees, which shed their leaves in fall, are bare over winter and grow new foliage in the spring. The precipitation is fairly uniform throughout. Soils of temperate forests are podozolic and fairly deep.

Parts of the world that have Mediterranean type of climate are characterised by warm, dry summers and cool, moist winters. These are commonly inhabitated by low broad leafed evergreen trees. Fire is an important hazardous factor in this ecosystem and the adaptation of the plants enable them to regenerate quickly after being burnt.

Here, the rainfall is high, and fog may be very heavy. It is the important source of water through rainfall itself. The biotic diversity of temperate rain forests is high as compared to other temperate forest. However, the diversity of plants and animals is much low as compared to the tropical rainforest.

Tropical rain forests occur near the equator. Tropical rain forests are among the most diverse and rich communities on the earth. Both temperature and humidity remain high and more or less uniform. The annual rainfall exceeds 200 cm and is generally distributed throughout the year. The flora is highly diversified. The extreme dense vegetation of the tropical rain forests remains vertically stratified. 

The lowest layer is an understory of trees, shrubs, herbs etc. Soil of tropical rainforests are very thick. The high rate of leaching makes these soils virtually useless for agricultural purposes, but when left undisturbed, the rapid cycling of nutrients within the litter layer, formed due to decomposition can compensate for the natural poverty of the soil. Undergrowth is restricted in many areas by the lack of sunlight at ground level.

The grasslands are found where rainfall is about 25-75 cm per year, not enough to support a forest, but more than that of a true desert. Typical grasslands are vegetation formations that are generally found in temperate climates.
In India, they are found mainly in the high Himalayas. The rest of India’s grasslands are mainly composed of steppes and savannas. 

Steppe formations occupy large areas of sandy and saline soil in western Rajasthan, where the climate is semi-arid, average rainfall is less than 200 mm a year with a dry season of 10 to 11 months, and a large variation in rainfall.

In the central and eastern parts of Rajasthan, where the rainfall is about 500 mm year and the dry season is of six to eight months, dry savanna grazing ecosystems have developed. 
the grasses.

Deserts are formed in regions with less than 25 cm of annual rainfall. Lack of rain in the mid latitude is often due to
stable high pressure zones. The deserts are located in the temperate regions of ran shadow zones, where high mountains block off moisture from the seas. 

Adaptations: Desert plants are under hot and dry conditions. These plants conserve water by following methods:
> They are mostly shrubs.
> Leaves are absent or reduced in size.
> Leaves and stem are succulent and water storing.
> In some plants even the stem contains chlorophyll for photosynthesis.
> Root system is well developed and spread over large area.

The animals are physiologically and behaviorally adapted to desert conditions.
> They are fast runners.
> They are nocturnal in habit to avoid the sun’s heat during day time.
> They conserve water by excreting concentrated urine.
> Animals and birds usually have long legs to keep the body away from the hot ground.
> Lizards are mostly insectivorous and can live without drinking water for several days.
> Herbivorous animals get sufficient water from the seeds which they eat.


Deforestation means wanton cutting of trees including repeated lopping, felling, removal of forest litter, browsing, grazing and trampling of seedlings. It results mainly from

    1) Shifting cultivation

    2) Development projects

    3) Demand for fuel wood

    4) Demand for wood for industry and for commercial purposes

    5) Other causes.

This method of cultivation is practiced all over the world but is more prevalent in the tropical countries. In this practice a patch of land is cleared, vegetation is burned and the ash is mixed with the soil thus adding nutrients to the soil.

This patch of land is used for raising crops for 2 to 3 years, and this yield is modest. In India it is widely practiced in North Eastern region comprising the states of Assam, Meghalaya, Nagaland, Manipur, Tripura, Arunachal Pradesh and Mizoram and in Andaman Nocobar islands.

This is locally known as Jhum in North Eastern region, Podu in Andhra Pradesh, Bewar or Dahza in Madhya Pradesh, in Orissa it is known as the dahi, gudiya and chas.

Aquatic Ecosystem

Ecosystems consisting of water as the main habitat are known as aquatic ecosystems:

Aquatic ecosystems are classified based on their salt content.

  1. Fresh water ecosystems- The salt content of fresh bodies is very low, always less than 5 ppt (parts per thousand). E.g. lakes, ponds, pools, springs, streams, and rivers. 
  2. Marine ecosystems – the water bodies containing salt concentration equal to or above that of sea water (i.e., 35 ppt or above) like shallow seas and Open Ocean.
  3. Brackish water ecosystems – these water bodies have salt content in between 5 to 35 ppt. e.g. estuaries, salt marshes, mangrove swamp and forests. 

These are unattached organisms which live at the air-water interface such as floating plants etc. Some organisms spend most of their lives on top of the air-water interface such as water striders, while others spend most of their time just beneath the air-water interface and obtain most of their food within the water.

These are organisms which remain attached to stems and leaves of rooted plants or substances emerging above the bottom. 

This group includes both microscopic plants like algae (phytoplankton) arid animals like crustaceans and protozoans (zooplankton) found in all aquatic ecosystems except certain swift moving waters.

This group contains animals which are swimmers. The nektons are relatively large and powerful as they have to overcome the water currents. The animals range in size from the swimming insects (about 2 mm long) to the largest animals, the blue whale.

They are found on the bottom of the aquatic ecosystem.

Sunlight and Oxygen are most important limiting factors of the aquatic ecosystems whereas moisture and temperature are the main limiting factors of terrestrial ecosystem.

Sunlight penetration rapidly diminishes as it passes down the column of water. The depth to which light penetrates a lake determines the extent of plant distribution. Based on light penetration and plant distribution they are classified as photic and aphotic zones. 

Photic Zone: The upper zone in the aquatic system which is exposed to light. Here, both photosynthesis and respiration takes place.

Aphotic Zone: The lower layer in the aquatic ecosystem where the light penetration is limited leading to restricted growth of plants. Only Respiration takes place. No Photosynthesis.

There are three zones in a lake, depending upon penetration of light:

(i) The littoral zone is the shallow water zone around the edge of the lake which supports rooted vegetation; light penetrates through the shallow water.

(ii) Limnetic Zone: The open water zone beyond the littoral zone is the limnetic zone, where phytoplankton grows in abundance. In the limnetic zone, light may penetrate up to 20 to 40 m, depending upon the clarity of water.

(iii) Profundal Zone: The dark zone, where light does not reach, is known as the profundal zone. The sediments at the bottom of lakes and ponds form the benthic region which is a habitat for benthic organisms like snails, slugs and micro-organisms.

Note: The Littoral zone and the limnetic zone are classified horizontally.

Note: The plantation of commercial viable plants have caused damage to the indigenous species of the plants. For example the promotion of teak plantation in south India has replaced the natural plants in south India.

Winterkill: Snow cover of ice on water body can effectively cut off light, plunging the waters into darkness. Hence photosynthesis stops but respiration continues. Thus in shallow lakes, the oxygen get depleted. Fish die, but we won’t know it until the ice melts and we find floating fish. This condition is known as winterkill.

In aquatic ecosystems oxygen is dissolved in water, where its concentration varies constantly depending on factors
that influence the input and output of oxygen in water. In fresh water the average concentration of dissolved oxygen
is 0.0010 per cent (also expressed as 10 parts per million or 10 ppm) by weight, which is 150 times lower than
the concentration of oxygen in an equivalent volume of air.

Oxygen enters the aquatic ecosystem through the air water interface and by the photosynthetic activities of aquatic plants. Therefore, the quantity of dissolved oxygen present in an ecosystem depends on the rate at which the aforesaid two processes occur.

Dissolved oxygen escapes the water body through air-water interface and through respiration of organisms
(fish, decomposers, zooplanktons, etc.). The amount of dissolved oxygen retained in water is also influenced by
Oxygen is less soluble in warm water. Warm water also enhances decomposer activity. Therefore, increasing the temperature of a waterbody increases the rate at which oxygen is depleted from water.

When the dissolved oxygen level falls below 3-5 ppm, many aquatic organisms are likely to die.

Transparency affects the extent of light penetration. Suspended particulate matters such as clay, silt, phytoplankton, etc. make the water turbid. Consequently it limits the extent of light penetration and the photosynthetic activity in a significant way.

The water temperature changes less rapidly than the temperature of air because water has a considerably higher specific heat than air, i.e. larger amounts of heat energy must be added to or taken away from water to raise or lower
its temperature. 

Since water temperatures are less subject to change, the aquatic organisms have narrow temperature tolerance limit. As a result, even small changes in water temperature are a great threat to the survival of aquatic organisms when compared to the changes in air temperatures in the terrestrial organisms. 

A body of standing water, generally large enough in area and depth, irrespective of its hydrology , ecology, and other characteristics is generally known as lake.

Like any organism, lakes are born as the originate by various geological and geomorphic events, and grow with time to change their various morphological and functional characteristics and eventually die.

They receive their water from surface runoff (sometimes also groundwater discharge) and along with it various chemical substances and mineral matter eroded from the land. Over periods spanning millennia, ‘ageing’ occurs as the lakes accumulate mineral and organic matter and gradually, get filled up.

Classification of Lakes: 

On the basis of their nutrient content, they are categorized as Oligotrophic (very low nutrients), Mesotrophic (moderate nutrients) and Eutrophic (highly nutrient rich). Vast majority of lakes in India are either eutrophic or mesotrophic because of the nutrients derived from their surroundings or organic wastes entering them.


The nutrients flowing from the terrestrial ecosystem to the aquatic ecosystem promotes the growth of algae in the aquatic ecosystem. The nitrates and phosphates from the farm flow into the lake along with rainwater. This boosts the algal growth known as the algal bloom.

The algae dies and is degraded by the bacteria on the bottom of the aquatic ecosystem. The bacteria require oxygen which is supplied by the dissolved Oxygen in the water. This reduces the dissolved oxygen in the water. Eutrophication is the natural aging of a lake by biological enrichment of its water. 

In a young lake the water is cold and clear, supporting little life. With time, streams draining into the lake introduce nutrients such as nitrogen and phosphorus, which encourage the growth of aquatic organisms. As the lake’s fertility increases, plant and animal life burgeons, and organic remains begin to be deposited on the lake bottom. Over the centuries, as silt and organic debris pile up, the lake grows shallower and warmer, with warm-water organisms supplanting those that thrive in a cold environment. 

Marsh plants take root in the shallows and begin to fill in the original lake basin. Eventually, the lake gives way to large masses of floating plants (bog), finally converting into land. Depending on climate, size of the lake and other factors, the natural aging of a lake may span thousands of years. However, pollutants from man’s activities like effluents from the industries and homes can radically accelerate the aging process. This phenomenon has been called Cultural or Accelerated Eutrophication.

Algae or phytoplankton are microscopic organisms that can be found naturally in coastal waters. They are major producers of oxygen and food for many of the animals that live in these waters.

When environmental conditions are favorable for their development, these cells may multiply rapidly and form high numbers of cells and this is called an algal bloom.

A bloom often results in a color change in the water. Algal blooms can be any color, but the most common ones are red or brown. These blooms are commonly referred to as red or brown tide. 

Most algal blooms are not harmful but some produce toxins and do affect fish, birds, marine mammals and humans. The toxins may also make the surrounding air difficult to breathe. These are known as Harmful Algal Blooms (HABs). 

HABs can deplete oxygen in water and lead to low dissolved oxygen levels.

How it depletes oxygen?

When masses of algae die and decompose, the decaying process can deplete oxygen in the water, causing the water to become so low in oxygen. When oxygen levels become too low, fish suffocate and die.

Some algae species in blooms produce potent neurotoxins that can be transferred through the food web where they affect and even kill the higher forms of life such as zooplankton, shellfish, fish, birds, marine mammals, and even humans that feed either directly or indirectly on them.

What is the use of algae?

Most species of algae or phytoplankton serve as the energy producers at the base of the food web, without which higher life on this planet would not exist.

Why Red Tide is a misnomer?

“Red Tide” is a common name for such a phenomenon where certain phytoplankton species contain pigments and “bloom” such that the human eye perceives the water to be discolored.

Blooms can appear greenish, brown, and even reddish orange depending upon the type of organism, the type of water, and the concentration of the organisms.

Blooms can be due to a number of reasons. Two common causes are nutrient enrichment and warm waters. 

Wetlands are areas intermediate in character between deep-water and terrestrial habitats, also transitional in nature, and often located between them. These habitats experience periodic flooding from adjacent deep water habitats and therefore supports plants and animals specifically adapted to such shallow flooding or water logging of the substrate, were designated as wetlands.

They included lake littorals (marginal areas between highest and lowest water level of the lakes), floodplains (areas lying adjacent to the river channels beyond the natural levees and periodically flooded during high discharge in the river) and other marshy or swampy areas where water gets stagnated due to poor drainage or relatively impervious substrata & Bogs, fens and mangroves due to similar ecological characteristics. 

Functions of Wetlands

  • Habitat to aquatic flora and fauna, as well as numerous species of birds, including migratory species. 
  • Filtration of sediments and nutrients from surface water 
  • Nutrients recycling 
  • Water purification
  • Floods mitigation
  • Maintenance of stream flow
  • Ground water recharging
  • Provide drinking water, fish, fodder, fuel, etc.
  • Control rate of runoff in urban areas
  • Buffer shorelines against erosion
  • Comprise an important resource for sustainable tourism, recreation and cultural heritage
  • Stabilization of local climate
  • Source of livelihood to local people
  • Genetic reservoir for various species of plants
  • Supporting specific diversity

Reasons for depletion

  • Conversion of lands for agriculture
  • Overgrazing
  • Removal of sand from beds
  • Aqua culture
  • Habitat Destruction and Deforestation
  • Pollution
  • Domestic waste
  • Agricultural runoff
  • Industrial effluents
  • Climate change


  • Survey and demarcation
  • Protection of natural regeneration
  • Artificial regeneration
  • Protective measures
  • Afforestation (percentage survival indicated)
  • Weed control
  • Soil conservation measures & afforestation
  • Wildlife conservation
  • Removal of encroachments
  • Eutrophication abatement
  • Environmental awareness

Criteria for Identification of Wetlands of National Importance

Criteria for identification of wetlands of national importance under NWCP are same as those prescribed under the ‘Ramsar Convention on Wetlands’ and are as given below:

Criteria based on species and ecological communities
(1) If it supports vulnerable, endangered, or critically endangered species; or threatened ecological communities.
(2) If it supports populations of plant and/or animal species important for maintaining the biological diversity of a particular biogeographic region.
(3) If it supports plant and/or animal species at a critical stage in their life cycles, or provides refuge during adverse conditions.

Specific criteria based on water birds

(4) If it regularly supports 20,000 or more water birds.
(5) If it regularly supports 1 % of the individuals in a population of one species or subspecies of water birds.

Specific criteria based on fish

(6) If it supports a significant proportion of indigenous fish subspecies, species or families, life-history stages, species interactions and/or populations that are representative of wetland benefits and/or values and thereby contributes to global biological diversity.

(7) If it is an important source of food for fishes, spawning ground, nursery and/or migration path on which fish stocks, either within the wetland or elsewhere, depend. Specific criteria based on water/life and culture 

(ix) If it is an important source of food and water resource, increased possibilities for recreation and eco-tourism, improved scenic values, educational opportunities, conservation of cultural heritage (historic or religious sites).

Estuaries are located where river meets the sea. Estuaries are water bodies where the flow of freshwater from river mixes with salt water transported, by tide, from the ocean.

Estuaries are the most productive water bodies in the world. They are located at the lower end of a river and are subject to tidal fluctuations.

Estuaries are either once or twice, daily washed by the seawater.

Characters: An Estuary is a semi enclosed coastal body of water with one or more rivers or streams flowing into it. It has a free connection with open sea. The complete salinity range from 0-35 ppm is seen from the head (river end) to the mouth (sea end) of an estuary.

An estuary has very little wave action, so it provides a calm refuge from the open sea. It provides the shelter for some of the animals. It is the most productive region as it receives the high amount of nutrients from fresh and marine water.

Estuaries are most heavily populated areas throughout the world, with about 60% of the world’s population living along estuaries and the coast.

Estuaries are typically classified by their geomorphological features or by water circulation patterns and can be referred to by many different names, such as bays, harbors, lagoons, inlets, etc.

Coastal lakes which have their connection with the sea through small openings are better known as lagoons or backwaters.

They exhibit a gradient in salinity from freshwater to marine depending upon the extent of influence of the sea water.

Estuary Formation: Most estuaries can be grouped into four geomorphic categories based on the physical processes responsible for their formation: (1) Rising sea level; (2) movement of sand and sandbars; (3) glacial processes; and (4) tectonic processes.

Mangroves are the characteristic littoral plant formation of tropical and subtropical sheltered coastlines. Mangroves are trees and bushes growing below the high water level of spring tides which exhibits remarkable capacity for salt water tolerance.

Characteristics of mangroves

  • They are basically evergreen land plants growing on sheltered shores, typically on tidal flats, deltas, estuaries, bays, creeks and the barrier islands.
  • The best locations are where abundant silt is brought down by rivers or on the backshore of accreting sandy beaches.
  • Their physiological adaptation to salinity stress and to water logged anaerobic mud is high.
  • They require high solar radiation and have the ability to absorb fresh water from saline/ brackish water.
  • It produces pneumatophores (blind roots) to overcome respiration problem in the anaerobic soil conditions.
  • Pneumatophores are specialized root structures that grow out from the water surface and facilitate the aeration necessary for root respiration in hydrophytic trees such as many mangrove species.
  • Mangroves exhibit viviparity mode of reproduction. I.e. seeds germinate in the tree itself (before falling to the ground). This is an adaptive mechanism to do overcome the problem of germination in saline water.

Mangrove profile in India

  • The mangroves of Sundarbans are the largest single block of tidal holophytic mangroves of the world.
  • This mangrove forest is famous for the Royal Bengal Tiger and crocodiles. Mangrove areas are being cleared for agricultural use.
  • The mangroves of Bhitarkanika (Orissa), which is the second largest in the Indian sub-continent, harbor high concentration of typical mangrove species and high genetic diversity.
  • Mangrove swamps occur in profusion in the intertidal mudflats on both sides of the creeks in the Godavari-Krishna deltaic regions of Andhra Pradesh.

Role of mangroves

Mangrove plants have (additional) special roots such as prop roots, pneumatophores which help to impede water flow and thereby enhance the deposition of sediment in areas (where it is already occurring), stabilize the coastal shores, provide breeding ground for fishes.


  • Mangroves moderate monsoonal tidal floods’ and reduce inundation of coastal lowlands.
  • It prevents coastal soil erosion. It protects coastal lands from tsunami, hurricanes and floods.
  • Mangroves enhance natural recycling of nutrients.
  • Mangrove supports numerous flora, avifauna and wild life.
  • Provide a safe and favorable environment for breeding, spawning, rearing of several fishes.
  • It protects coastal inland from adverst climatic elements.
  • It supplies woods, fire wood, medicine plants and edible plants to local people.

Coral is actually a living animal. Coral has a symbiotic relationship (each gives something to the other and gets something back in return) with ‘zooxanthellae’ microscopic algae which live on coral [i.e. instead of living on the sea floor, the algae lives up on the coral which is closer to the ocean surface and so that the algae gets lots of light].

Zooxanthellae assist the coral in nutrient production through its photosynthetic activities. These activities provide the coral with fixed carbon compounds for energy, enhance calcification ,and mediate elemental nutrient flux. The tissues of corals themselves are actually not the beautiful colors of the coral reef, but are instead clear (white). The corals receive their coloration from the zooxanthellae living within their tissues.

The host coral polyp in return provides its zooxanthellae with a protected environment to live within, and a steady supply of carbon dioxide for its photosynthetic processes. 

There are two types of corals: hard corals and soft corals. Only hard corals build reefs. 

The builders of coral reefs are tiny animals called polyps. As these polyps thrive, grow, then die, they leave their limestone (calcium carbonate) skeletons behind. The limestone is colonized by new polyps. Therefore, a coral reef is built up of layers of these skeletons covered ultimately by living polyps. The reef-building, or hermatypic corals can form a wide range of shapes. 

Coral reefs may be branched, table-like, or look like massive cups, boulders or knobs. While the majority of coral reefs are found in tropical and sub-tropical water, there are also deep water corals in colder regions.

Conditions for growth of Corals

  • They occur in shallow tropical areas where the sea water is clean, clear arid warm 
  •  Corals are highly susceptible to quick changes. They grow in regions where climate is significantly stable for a long period of time.
  • Corals thrive in tropical waters [30°N and 30°S latitudes, the temperature of water is around 20°C] where diurnal and annual temperature ranges are very narrow.
  • Coral require fairly good amount of sunlight to survive. The ideal depths for coral growth are 45 m to 55 m below sea surface, where there is abundant sunlight available.
  • Clear salt water is suitable for coral growth, while both fresh water and highly saline water are harmful.
  • Adequate supply of oxygen and microscopic marine food, called plankton [phytoplankton], is essential for growth. As the plankton is more abundant on the seaward side, corals grow rapidly on the seaward side.
  • Corals are highly fragile and are vulnerable to climate change and pollution and even a minute increase in marine pollution can be catastrophic.
Functions of Coral Reefs
  • Coral reefs are natural protective barriers against erosion and storm surge. 
  • To capturing plankton from the water, thereby capturing nutrients. 
  • Largest biogenic calcium carbonate producer. 
  • They provide substrate for mangroves
  • Coral reefs provide habitat for a large variety of animals and plants including avifauna.
  • Natural causes may be due to the outbreak of reef destroying mechanisms, “bleaching” and depletion of essential symbiotic relation.
  • Anthropogenic causes may be due to chemical pollution (pesticides, cosmetics, etc.), industrial pollution, mechanical damage, nutrient loading or sediment loading, Dredging, shipping, tourism, mining or collection, thermal pollution, intensive fishing, etc.
  • Coral reef ecosystems world wide have been subject to unprecedented degradation over the past few decades. Disturbances affecting coral reefs include anthropogenic and natural events. Recent accelerated coral reef decline seems to be related mostly to anthropogenic. 
  • Coral reef bleaching is a common stress response of corals to many of the various disturbances. 
Coral Bleaching
Bleaching, or the paling of coral colour occurs when: 
(i) the densities of zooxanthellae decline and/or
(ii) the concentration of photosynthetic pigments within the zooxanthellae fall.
  • When corals bleach they commonly lose 60-90% of their zooxanthellae and each zooxanthella may lose 50-80% of its photosynthetic pigments. 
  • If the stress-causing bleaching is not too severe and if it decreases in time, the affected corals usually regain their symbiotic algae within several weeks or a few months.
  • If zooxanthellae loss is prolonged, i.e. if the stress continues and depleted zooxanthellae populations do not recover, the coral host eventually dies. 
  • High temperature and irradiance stressors have been implicated in the disruption of enzyme systems in zooxanthellae that offer protection against oxygen toxicity. 
  • Photosynthesis pathways in zooxanthallae are impaired at temperatures above 30 degrees C, this effect could activate the disassociation of coral/algal symbiosis.
  • Low or high temperature shocks results in zooxanthellae low as a result of cell adhesion dysfunction.

Ecological causes of coral bleaching

Following factors have been implicated in coral reef bleaching events.

  • Temperature (Major Cause):  Coral species live within a relatively narrow temperature margin, and anomalously low and high sea temperatures can induce coral bleaching. Bleaching is much more frequently reported from elevated sea water temperature. Bleaching events also occur during sudden temperature drops accompanying intense upwelling episodes, seasonal cold-air outbreaks.
  • Solar Irradiance: Bleaching during the summer months, during seasonal temperature and irradiance maxima often occurs disproportionately in shallow living corals and on the exposed summits of colonies. Solar radiation has been suspected to play a role in coral bleaching.
  • Subaerial Exposure: Sudden exposure of reef flat corals to the atmosphere during events such as extreme low tides, ENSO related sea level drops or tectonic uplift can potentially induce bleaching.
  • Sedimentation: Relatively few instances of coral bleaching have been linked solely to sediment. It is possible, but has not been demonstrated, that sediment loading could make zooxanthellate species more likely to bleach.
  • Fresh Water Dilution: Rapid dilution of reef waters from storm generated precipitation and runoff has been demonstrated to cause coral reef bleaching.
  • Inorganic Nutrients: Rather than causing coral reef bleaching, an increase in ambient elemental nutrient concentrations (e.g. ammonia and nitrate) actually increases zooxanthellae densities 2-3 times. Although eutrophication is not directly involved in zooxanthellae loss, it could cause secondary adverse affects such as lowering of coral resistance and greater susceptibility to diseases. 
  • Xenobiotics: Zooxanthellae loss occurs during exposure of coral to elevated concentrations of various  chemical contaminants, such as Cu.  Because high concentrations of xenobiotics are required to induce zooxanthellae loss, bleaching from such sources is usually extremely localized. 
  • Epizootics:  Pathogen induced bleaching is different from other sorts of bleaching. Most coral diseases cause patchy or whole colony death and sloughing of soft tissues, resulting in a white skeleton (not to be confused with bleached corals). A few pathogens have been identified the cause translucent white tissues, a protozoan.


A biome is defined by a broad-scale collection of flora and fauna that although different in detail from ecosystem to ecosystem share some commonalities.

Tropical rain forest: These are found in the high rain fall areas on either side of the equator, having high temperature and high humidity and receive above 200 cm of rainfall per year. Here, the Soil is rich in humus.

Temperate deciduous forest Biome: This type of forest, dominated by broad-leaved deciduous trees. Temperate deciduous forest consists largely of trees that drop their leaves during the cold season. It is characteristic of the marine west coast and moist continental climates. There is a longer growing season, higher light intensity, and a moderate amount of precipitation of between 50 and 150 cm per annum.


Boreal Forest: Boreal forest is the cold-climate needle leaf forest of high latitudes. It occurs in two great continental belts, one in North America and one in Eurasia.

Grassland Biome: Grasslands are areas dominated by grasses. They occupy about 20% of the land on the earth’s surface. Grasslands occur in both in tropical and temperate regions where rainfall is not enough to support the growth of trees. Grasslands are known by various names in different parts of the world. Grasslands are found in areas having well defined hot and dry, warm and rainy seasons.



North America




South America






Savanna Biome: Tropical grasslands are commonly called Savannas. They occur in eastern Africa, South America, Australia and India. Savannas form a complex ecosystem with scattered medium size trees in grass lands. The savanna biome is usually associated with the tropical wet dry climate of Africa and South America. Its vegetation ranges from woodland to grassland. In savanna woodland, the trees are spaced rather widely apart because there is not enough soil moisture during the dry season to support a full tree cover. The woodland has an open, park like appearance. 

Savanna woodland usually lies in a broad belt adjacent to equatorial rainforest. Savanna biome vegetation is described as rain green. Fires occur frequently in the savanna woodland during the dry season, but the tree species are particularly resistant to fire.

Taiga: Here the climate is moderate than Tundra but similar. It is found in Northern Europe, Asia and North America. The dominating vegetation include thick and coniferous forests such as spruce, pine, and fir. 


Series of protected areas linked through a global network, intended to demonstrate the relationship between conservation and development. Some Examples are: 

Mahendragiri Biosphere Reserve: The Odisha government has proposed a second biosphere reserve in the southern part of the state at Mahendragiri, a hill ecosystem having rich biodiversity.

Similipal Biosphere Reserve: It is around 470,955 hectares and is spread over Gajapati and Ganjam districts in the Eastern Ghats.

Environmental Pollution

Pollution is defined as an addition or excessive addition of certain materials to the physical environment (water, air and lands), making it less fit or unfit for life’. 

Pollutants are the materials or factors, which cause adverse effect on the natural quality of any component of the environment for example, smoke from industries and automobiles, chemicals from factories, radioactive substances from nuclear plants, sewage of houses and discarded household articles are the common pollutants.

Carbon monoxide (CO): It is a colourless, odourless gas that is produced by the incomplete burning of carbon based fuels including petrol, diesel, and wood. It is also produced from the combustion of natural and synthetic products such as cigarettes. It lowers the amount of oxygen that enters our blood.

Carbon dioxide (C02): It is the principle greenhouse gas emitted as a result of human activities such as the burning of coal, oil, and natural gases.

Chloroflorocarbons (CFC): These are gases that are released mainly from air-conditioning systems and refrigeration. When released into the air, CFCs rise to the stratosphere, where they come in contact with few other gases, which lead to a reduction of the ozone layer that protects the earth from the harmful ultraviolet rays of the sun. 

Lead: It is present in petrol, diesel, lead batteries, paints, hair dye products, etc. Lead affects children in particular. It can cause nervous system damage and digestive problems and, in some. cases, cause cancer.

Ozone: It occurs naturally in the upper layers of the atmosphere. This important gas shields the earth from the hanrmful ultraviolet rays of the sun. However, at the ground level, it is a pollutant with highly toxic effects. Vehicles and industries are the major source of ground-level ozone emissions. Ozone makes our eyes itch, bum, and water. It
lowers our resistance to cold and pneumonia. 

Nitrogen Oxide (Nox): It causes smog and acid rain. It is produced from burning fuels including petrol, diesel, and coal. Nitrogen oxide can make children susceptible to respiratory diseases in winters.

Suspended particulate matter (SPM): It consists of solids in the air in the form of smoke, dust, and vapour that can remain suspended for extended periods and is also the main source of haze which reduces visibility. The finer of these particles, when breathed in can lodge in our lungs and cause lung damage and respiratory problems.

Sulphur dioxide (S02): It is a gas produced from burning coal, mainly in thermal power plants. Some industrial processes, such as production of paper and smelting of metals, produce sulphur dioxide. It is a major contributor to smog and acid rain. Sulfur dioxide can lead to lung diseases.

Smog: Smog is a condition of fog that had soot or smoke in it. The smog is formed  as a result of the interaction of sunlight with certain chemicals in the atmosphere. One of the primary components of photochemical is ozone. While ozone in the stratosphere protects earth from harmful UV radiation, ozone on the ground is hazardous to human health. 

Ground level ozone is formed when vehicle emissions containing nitrogen oxides (primarily from vehicle exhaust) and volatile organic compounds (from paints, solvents, printing inks, petroleum products, vehicles, etc.) interact in the presence of sunlight.

Fly Ash: Ash is produced whenever combustion of solid material takes place. Fly ash is one such residue which rises with the gases into the atmosphere. Fly ash is a very fine powder and tends to travel far in the air. The ash which does not rise is termed as bottom ash. 

Composition of Fly Ash: 

1. Aluminium silicate (in large amounts)
2. silicon dioxide (Si02) and
3. Calcium oxide (CaO).
4. Fly ash particles are oxide rich and consist of silica, alumina, oxides of iron, calcium, and magnesium and toxic heavy metals like lead, arsenic, cobalt, and copper. 

How it is collected?
Fly ash is generally captured by electrostatic precipitators or other particle filtration equipment before the flue gases reach the chimneys of coal-fired power plants.

Environmental effects
1. If fly ash is not captured and disposed off properly, it can pollute air and water considerably.
2. It causes respiratory problems.
3. Fly ash in the air slowly settles on leaves and crops in fields in areas near to thermal power plants and lowers the plant yield.


  • Cement can be replaced by fly ash up to 35%, thus reducing the cost of construction, making roads, etc.
  • Fly ash bricks are light in weight and offer high strength and durability.
  • Fly ash is a better fill material for road embankments and in concrete roads.
  • Fly ash can be used in reclamation of wastelands.
  • Abandoned mines can be filled up with fly ash.
  • Fly ash can increase the crop yield and it also
  • It enhances water holding capacity of the land .

Addition of certain substances to the water such as organic, inorganic, biological, radiological, heat, which degrades the quality of water so that it becomes unfit for use. Water pollution is not only confined to surface water, but it has also spread to ground water, sea and ocean.

Types of sources

1. Point Sources: It is directly attributable to one influence. Here pollutant travels directly from source to water. Point sources are easy to regulate.

2. Non Point Source: It is from various ill defined and diffuse sources. They vary spatially and temporally and are difficult to regulate.

Source of water Pollution

1) Community waste water: It include discharges from houses, commercial and industrial establishments connected to public sewerage system. The sewage contains human and animal excreta, food residues, cleaning agents, detergents and other wastes.

2) Industrial Wastes: The industries discharge several inorganic and organic pollutants, which may prove highly toxic to the living beings.

3) Agricultural sources: Fertilizers contain major plant nutrients such as nitrogen, phosphorus and potassium. Excess fertilizers may reach the ground water by leaching or may be mixed with surface water of rivers, lakes and ponds by runoff and drainage. Pesticides include insecticides, fungicides, herbicides, rodenticides and soil
fumigants. Further, the animal excreta such as dung, wastes from poultry farms, piggeries and slaughter houses etc. reach the water though run off and surface leaching during rainy season. 

Thermal Pollution: The main sources are the thermal and nuclear power plants. The power plants use water as coolant and release hot waters to the original source. Sudden rise in temperature kills fishes and other aquatic animals.

Soil is a thin layer of organic and inorganic materials that covers the Earth’s rocky surface. Soil pollution is defined as the ‘addition of substances to the soil, which adversely affect physical, chemical and biological properties of soil and reduces its productivity.’

> It is build-up of persistent toxic compounds, chemicals, salts, radioactive materials, or disease causing agents in soil which have adverse effects on plant growth, human and animal health.

> A soil pollutant is any factor which deteriorates the quality, texture and mineral content of the· soil or which disturbs the biological balance of the organisms in the soil.


> Indiscriminate use of fertilizers, pesticides, insecticides and herbicides

> Dumping of large quantities of solid waste

> Deforestation and soil erosion.

> Pollution Due to Urbanization

Solid wastes are the discarded materials. Solid waste means any garbage, refuse, sludge from a wastewater treatment plant, or air pollution control facility and other discarded materials including solid, liquid, semi-solid, or contained gaseous material, resulting from industrial, commercial, mining and agricultural operations, and from community activities. But it does not include solid or dissolved materials in domestic sewage, or solid or dissolved materials in irrigation return flows or industrial discharges. 

Plastic Waste: Plastics are considered to be one of the wonderful inventions of 20th Century. They are widely used as packing and carry bags because of cost and convenience. But plastics are now considered as environmental hazard due to the “Throw away culture”.

Effects of Plastic Waste

  • The land gets littered by plastic bag garbage and becomes ugly and unhygienic.
  • Conventional plastics have been associated with reproductive problems in both humans and wildlife.
  • Dioxin (highly carcinogenic and toxic) by product of the manufacturing process is one of the chemicals believed to be passed on through breast milk to the nursing infant.
  • Burning of plastics, especially PVC releases this dioxin and also furan into the atmosphere. 

Thus, conventional plastics, right from their manufacture to their disposal are a major problem to the environment. Plastic bags can also contaminate foodstuffs due to leaching of toxic dyes and transfer of pathogens. Careless disposal of plastic bags chokes drains, blocks the porosity of the soil and causes problems for groundwater recharge.

Bioremediation is the use of microorganisms (bacteria and fungi) to degrade the environmental contaminants into less toxic forms.

Bioremediation Strategies:

(a) In situ bioremediation techniques: It involves treatment of the contaminated material at the site. Following strategies are followed for the in-situ bioremediation. 

Bioventing: Supply of air and nutrients through wells to contaminated soil to stimulate the growth of indigenous bacteria. It is used for simple hydrocarbons and can be used where the contamination is deep under the surface.

Biosparging: Injection of air under pressure below the water table to increase groundwater oxygen concentrations and enhance the rate of biological degradation of contaminants by naturally occurring bacteria.

Bio-augmentation: Microorganisms are imported to a contaminated site to enhance degradation process.

(b) Ex situ bioremediation techniques: Ex situ involves the removal of the contaminated material to be treated elsewhere.

Advantages of bioremediation

  • Useful for the complete destruction of a wide variety of contaminants
  • The complete destruction of target pollutants is possible.
  • Less expensive
  • Environment friendly

Disadvantages of bioremediation

  • Bioremediation is limited to those compounds that are biodegradable. Not all compounds are susceptible to rapid and complete degradation.
  • Biological processes are often highly specific.
  • Bioremediation often takes longer time than other treatment process.

Phytoremediation: Phytoremediation is use of plants to remove contaminants from soil and water.

Phytoaccumulation: is the process by which plants accumulate contaminants into the roots and aboveground shoots or leaves.

Phytotransformation: or Phytodegradation refers to the uptake of organic contaminants from soil, sediments, or water and their transformation to more stable, less toxic, less mobile form.

Phytostabilization: It is a technique in which plants reduce the mobility and migration of contaminated soil. Leachable constituents are adsorbed and bound into the plant structure so that they form unstable mass of plant from which the contaminants will not re-enter the environment.

Phytodegradation or rhizodegradation is the breakdown of contaminants through the activity existing in the rhizosphere. This activity is due to the presence of proteins and enzymes produced by the plants or by soil organisms such as bacteria, yeast, and fungi.

Rhizofiltration is a water remediation technique that involves the uptake of contaminants by plant root. Rhizofiltration is used to reduce contamination in natural wetlands and estuary areas.

Mycoremediation is a form of bioremediation in which fungi are used to decontaminate the area.

Mycofiltration is a similar process, using fungal mycelia to filter toxic waste and microorganisms from water in soil.

  • E-Waste is short for Electronic-Waste and the term is used to describe old, end-of-life or discarded electronic appliances. It includes their components, consumables, parts and spares.
  • E-waste is not hazardous if it is stocked in safe storage or recycled by scientific methods or transported from one place to the other in parts or in totality in the formal sector. The E-Waste can, however, be considered hazardous if recycled by primitive methods.
  • Laws to manage e-waste have been in place in India since 2011, mandating that only authorised dismantlers and recyclers collect e-waste. E-waste (Management) Rules, 2016 was enacted in 2017.
  • India’s first e-waste clinic for segregating, processing and disposal of waste from household and commercial units has been be set-up in Bhopal, Madhya Pradesh.

Health Effects of E-Waste

  • Lead: Causes damage to nervous system, Blood System, Kidney and Reproductive system. It is widely used in Glass Panels and in Computer Screen.  
  • Cadmium: Occurs in Semiconductor chip used in the computer. Toxic cadmium compounds accumulate in the human body, especially the kidneys.
  • Mercury: It is estimated that 22 % of the yearly world consumption of mercury is used in electrical and electronic equipment. Mercury is used in thermostats, sensors, relays, switches, medical equipment, lamps, mobile phones and in batteries. Mercury, used in flat panel displays, will likely increase as their use replaces cathode ray tubes. 

E-Waste Management Rules, 2016

  • The Ministry of Environment, Forest and Climate Change notified the E-Waste Management Rules, 2016 in supersession of the E-waste (Management & Handling) Rules, 2011.
  • Over 21 products (Schedule-I) were included under the purview of the rule. It included Compact Fluorescent Lamp (CFL) and other mercury containing lamps, as well as other such equipment.
  • For the first time, the rules brought the producers under Extended Producer Responsibility (EPR), along with targets. Producers have been made responsible for the collection of E-waste and for its exchange.
  • Various producers can have a separate Producer Responsibility Organisation (PRO) and ensure collection of E-waste, as well as its disposal in an environmentally sound manner.
  • Deposit Refund Scheme has been introduced as an additional economic instrument wherein the producer charges an additional amount as a deposit at the time of sale of the electrical and electronic equipment and returns it to the consumer along with interest when the end-of-life electrical and electronic equipment is returned.
  • The role of State Governments has been also introduced to ensure safety, health and skill development of the workers involved in dismantling and recycling operations.
  • A provision of penalty for violation of rules has also been introduced.
  • Urban Local Bodies (Municipal Committee/Council/Corporation) have been assigned the duty to collect and channelize the orphan products to authorized dismantlers or recyclers.
  • Allocation of proper space to existing and upcoming industrial units for e-waste dismantling and recycling.

Radioactivity is a phenomenon of spontaneous emission of proton (Alpha-particles), electrons (Beta-particles) and gamma rays (short wave electromagnetic waves) due to disintegration of atomic nuclei of some elements. These cause radioactive pollution.

Types of radiation particles

  1. Alpha particles can be blocked by a piece of paper and human skin.
  2. Beta particles can penetrate through skin, while can be blocked by some pieces of glass and metal.
  3. Gamma rays can penetrate easily to human skin and damage cells on its way through, reaching far, and can only be blocked by a very thick, strong, massive piece of concrete.

Radiations are of two types with regard to the mode of their action on cells.

  1. Non-ionizing radiations: They include short-wave radiations such as ultraviolet rays, which forms a part of solar radiation. They have low penetrating power and affect the cells and molecules which absorb them. They damage eyes which may be caused by reflections from coastal sand, snow (snow blindness) directly looking towards sun during eclipse. They injure the cells of skin and blood capillaries producing blisters and reddening called sunburns.
  2. Ionizing radiations: They include X-rays, cosmic rays and atomic radiations (radiations emitted by radioactive elements). Ionizing radiations have high penetration power and cause breakage of macro moleculesThe molecular damage may produce short range (immediate) or long range (delayed) effects. Short range effects include bums, impaired metabolism, dead tissues and death of the organisms, the long range effects are mutations increased incidence of tumors and cancer, shortening of life-span and developmental changes. The mutated gene can persist in living organisms and may affect their progeny.

Noise pollution is an unpleasant noise created by people or machines that can be annoying, distracting, intrusive, and/or physically painful. Noise pollution comes from sources such as “road traffic, jet planes, garbage trucks, construction equipment, manufacturing processes etc. 

Sound is measured in decibels (dB). An increase of about 10 dB is approximately double the increase in loudness. A person’s hearing can be damaged if exposed to noise levels over 75 dB over a prolonged period of time. The World Health Organization recommends that the sound level indoors should be less than 30 dB.

Environmental Impact Assessment (EIA)

Environmental Impact Assessment (EIA) is a tool to anticipate the likely environmental impacts that may arise out of the proposed developmental activities and suggest mitigation measures and strategies.

The initiative is started with the Notification on Environmental Impact Assessment (EIA) of developmental projects in 1994 under the provisions of Environment (Protection) Act, 1986 making EIA mandatory for 29 categories of developmental projects.

Every anthropogenic activity has impact on the environment. More often it is harmful to the environment than benign. However, mankind as it is developed today cannot live without taking up these activities for his food, security and other needs. Consequently, there is a need to harmonise developmental activities with the environmental concerns.

EIA integrates the environmental concerns with developmental activities right at the time of initiating for preparing the feasibility report, in doing so it can enable the integration of environmental concerns and mitigation measures in project development.

EIA can often prevent future liabilities or expensive alterations in project design.


Environmental clearance or the ‘go ahead’ signal is granted by the Impact Assessment Agency in the Ministry of Environment and Forests, Government of India.

Environmental clearance or the ‘go ahead’ signal is granted by the Impact Assessment Agency in the Ministry of Environment and Forests, Government of India.

Environment Impact Assessment Notification of 2006 has categorized the developmental projects in two categories, i.e., Category A and Category B. ‘Category A: Projects are appraised at national level by expert appraisal committee.

India has constituted the State Level Environment Impact Assessment Authority (SEIAA) and State Level Expert Appraisal Committee (SEAC) to decentralize the environmental clearance process.

These institutions (at state level) are responsible for appraising certain categories of projects, termed as ‘Category B’ projects, which are below a prescribed threshold level.


Biodiversity is the variation in occurrence of different plants and species in an ecosystem. The current biodiversity is the result of constant evolution that started millions of years ago. 

The biodiversity is of three types.

Genetic Biodiversity: The genetic biodiversity refers to the variation in characteristics within members of the same species. For example, the two race of human may have different heights. The genetic biodiversity is essential for the existence of the species.

Species biodiversity: It refers to the richness of species in certain area.  Higher the number of species of higher is the diversity. High biodiversity is essential for the existence of species. The species are related to each other for the survival. Lesser is the diversity limited will be the option for existence. Higher biodiversity regions can adopt the changes easily. 

Ecological diversity: Occurrence of different ecosystem in the geographical expanse of a region is termed as ecological diversity.

The accelerated rates of species extinctions that the world is facing now are largely due to human activities.

  1. Habitat loss and fragmentation: This is the most important cause driving animals and plants to extinction. The most dramatic examples of habitat loss come from tropical rain forests. Once covering more than 14 per cent of the earth’s land surface, these rain forests now cover no more than 6 per cent.
  2. Over-exploitation: Humans have always depended on nature for food and shelter, but when ‘need’ turns to ‘greed’, it leads to over-exploitation of natural resources.
  3. Alien species invasions: When alien species are introduced unintentionally or deliberately for whatever purpose, some of them turn invasive, and cause decline or extinction of indigenous species. Species which are not the natural inhabitants of the local habitat but are introduced into the system are called exotic species.
  4. Co-extinctions: When a species becomes extinct, the plant and animal species associated with it in an obligatory way also become extinct.

‘Biodiversity hotspots’ are the regions with very high levels of species richness and high degree of endemism (that is, species confined to that region and not found anywhere else). The threat to the species due to habitat loss as a result of anthropogenic activities (Threat Perception) is also a criterion. Of the 34 globally identified biodiversity hotspots, India harbors two hotspots, i.e., Eastern Himalayas, Western Ghats.

This is the method of conservation in which the conservation of a species is done by protecting its habitat along with all the other species that live in it in nature. It includes, conserving a species in its own environment by creating National Parks and Wildlife Sanctuaries etc. 

When species are protected by making arrangements outside its natural habitat in a carefully controlled situation such as a botanical garden for plants or a zoological park for animals, where there is expertise to multiply the species under artificially managed conditions, it is known as the ex-situ conservation. There is also another form of preserving a plant by preserving its germ plasm in a gene bank so that it can be used if needed in future.

Diversity is a single statistic in which the number of species richness and evenness are compounded. Biodiversity is measured by two major components:

  1. species richness, and
  2. Species evenness.

(i) Species richness: It is the measure of number of species found in a community

  • Alpha diversity: It refers to the diversity within a particular area or ecosystem, and is usually expressed by the number of species (i.e., species richness) in that ecosystem.
  • Beta diversity: It is a comparison of diversity between ecosystems, usually measured as the change in amount of species between the ecosystems
  • Gamma diversity: It is a measure of the overall diversity for the different ecosystems within a region.

Imagine that you have a landscape containing of a number of separate sites and habitats. Alpha diversity is just the diversity of each site (local species pool). Beta diversity represents the differences in species composition among sites. Gamma diversity is the diversity of the entire landscape (regional species pool).

Note: Alpha diversity is related to one local ecosystem, Beta diversity among ecosystems and Gama diversity is related to entire ecosystem taken together. 

(ii) Species evenness: It measures the proportion of species at a given site, e.g. low evenness indicates that a few species dominate the site.

Biodiversity in India

India is one of the recognized megadiverse countries of the world. In terms of species richness, India ranks seventh in mammals, ninth in birds and fifth in reptiles. In terms of endemism of vertebrate groups, India’s position is tenth in birds with 69 species, fifth in reptiles with 156 species and seventh in amphibians with 110 species. 

India’s share of crops is 44% as compared to the world average of 11 %. India also has 23.39 % of its geographical area under forest and tree cover. Of the 34 globally identified biodiversity hotspots, India harbours two hotspots, i.e., Eastern Himalayas, Western Ghats. 

Biogeography deals with the geographical distribution of plants and animals. There are 10 biogeographic zones which are distinguished clearly in India. They are as follows –  

1) Trans-Himalayas: An extension of the Tibetan plateau,  harboring high-altitude cold desert in Laddakh (J&K) and Lahaul Spiti (H.P) comprising 5.7 % of the country’s landmass. 

2) Himalayas: The entire mountain chain running from north-western to northeastern India, comprising a diverse range of biotic provinces and biomes. 

3) Desert: The extremely arid area west of the Aravalli hill range, comprising both the salty desert of Gujarat and the sand desert of Rajasthan. 

4) Semi-arid: The zone between the desert and the Deccan plateau, including the Aravalli hill range.

5) Western Ghats: The hill ranges and plains running along the western coastline, south of the Tapti river, covering an extremely diverse range of biotic provinces and biomes.

6) Deccan peninsula: The largest of the zones, covering much of the southern and south-central plateau with a predominantly deciduous vegetation.

7) Gangetic plain: Defined by the Ganges river system, these plains are relatively homogenous. 

8) North-east India: The plains and non-Himalayan hill ranges of northeastern India, with a wide variation of vegetation.

9) Islands: The Andaman and Nicobar Islands in the Bay of Bengal, with a highly diverse set of biomes. 0.03% of the country’s landmass. 

10) Coasts: A large coastline distributed both the the west and east, with distinct differences between the two; Lakshadeep islands are included in this with the percent area being negligible.

1. Algae: Algae are defined as a group of predominantly aquatic, photosynthetic, and nucleus-bearing organisms that lack the true roots, stems, leaves, and specialized multicellular reproductive structures of plants.

The fresh-water algae are generally green or blue-green in colour, whereas the marine ones are red or brown. These are autotrophic plants, as they can manufacture their own food. 

2. Fungi: Non-green, non differentiated plants characterised by total absence of chlorophyll are called Fungi. They grow either on dead, rotten organic matters as saprophytes or live as parasites on other living bodies, which are referred to as hosts. Moulds and mushrooms are the familiar examples of saprophytic fungi. The maximum diversity of fungi is in the Western Ghats followed by the eastern Himalaya and the western Himalaya. About 3500 species are endemic to the country.

3. Bacteria: Non-chlorophyll, micro-organisms which lead saprophytic or parasitic existence. Many of them are pathogenic; Saprophytic bacteria are rather beneficial. They are soil borne and many of them are used in industries. 

4. Lichens: A lichen is a peculiar combination of an alga and a fungus, the two live deriving mutual benefit. They are group of greyish green plants which grow on rocks, three-trunks, dead wood, etc. · The algae manufactures carbohydrate food which becomes available to the fungus, and the latter absorbs and retains water and thus keeps the algal cells moist. So it is a nice example of symbiosis. They are most common in wetlands, rare in rivers and streams and are not found in ground water.

5. Protozoa: Protozoa are simple, single-celled animals. They are the smallest of all animals. Most protozoa are microscopic. They do breathe, move and reproduce like multi-celled animals e.g. amoebas, Flagellates, etc.

Animal Diversity in India

Species judged as threatened are listed by various agencies as well as by some private organizations. The most cited of these lists is the Red Data Book. It is a loose-leaf book on the status of many kinds of species. This volume is continually updated and is issued by the International Union for Conservation of Nature (IUCN) located in Morges, Switzerland

The Red Data Book is aimed at keeping a record of every endangered or rare species of animals and plants. 

Key Points to note about Red Data Book:

  • Through its master archives, data of every single endangered species of plants and fungi, and their subsequent sub-species is recorded in the Red Data Book.
  • Red Data Book entails detailed knowledge and collected information regarding the rare species and subspecies of a region.
  • Red Data Book is updated every quarter with extinction timelines.
  • The Book provides scientific information on the updated status of every endangered species and subspecies of a concentrated region.
  • Red Data Book records measures to protect and refurbish the endangered species, along with programs employed to monitor the said species.


A series of Regional Red Lists are produced by countries or organizations, which assess the risk of extinction to species within a political management unit.

The aim of the IUCN Red List is to convey the urgency of conservation issues to the public and policy makers, as well as help the international community to reduce species extinction. According to IUCN the formally stated goals of the Red List are to provide scientifically based information on the status of species and subspecies at a global level, to draw attention to the magnitude and importance of threatened biodiversity, to influence national and international policy and decision-making, and to provide information to guide actions to conserve biological diversity.

A taxon is Extinct when there is no reasonable doubt that the last individual has died

A taxon is Extinct in the Wild when it is known only to survive in cultivation, in captivity or as a naturalized population (or populations) well outside the past range. 

A taxon is Critically Endangered when the best available evidence indicates that it meets any of the following criteria for Critically Endangered.

  • Reduction in population (> 90% over the last 10 years),
  • Population size (number less than 50 mature individuals),
  • quantitative analysis showing the probability of extinction in wild in at least 50% in their 10 years) and
  • It is therefore considered to be facing an extremely high risk of extinction in the wild.

A taxon is endangered when the best available evidence indicates that it meets any of the criteria for Endangered


  • Reduction in population size (70% over the last 10 years)
  • Population size estimated to number fewer than 250 mature individuals,
  • Quantitative analysis showing the probability of extinction in wild in at least 20% within 20 years and
  • It is therefore considered to be facing a very high risk of extinction in the wild.

A taxon is Vulnerable when the best available evidence indicates that it meets any of the criteria for vulnerable i.e. 


  • Reduction in population (> 50% over the last 10 years)
  • Population size estimated to number fewer than 10,000 mature individuals,
  • Probability of extinction in wild is at least 10% within 100 years, and it is therefore considered to be facing high risk extinction in the wild.

A taxon is Near Threatened when it has been evaluated against the criteria but does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for or is likely to qualify for a threatened category in the near future.

Widespread and abundant taxa are included in this category.

Climate Change

Climate is defined as the long-term average of a region’s weather events. The phrase ‘climate change’ represents a change in the long-term weather patterns The measurable effects of the continual warming trend. Usually measured in major shifts in temperature, rainfall, snow, and wind patterns lasting decades or more


#1. What is the speed of Light in vacuum?

Speed of Light remains same in Vacuum.

#2. Which of the following is not a raw-material for fertilizer industry?

Ans: (D)

Solution: Factual Question

#3. Non-metallic mineral is

Ans: (A)

Solution: Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite. It is not metallic.


#4. There are how many pairs of cranial nerves in human?

Ans: (B)

Solution: There are 12 pairs of cranial nerves in humans.

#5. The pyramid of energy in any ecosystem is

Ans: (A)

Solution: The pyramid of energy, however, is always upright.

Ecological Pyramid: Common parameters used for constructing ecological pyramids are the number of individuals (pyramid of numbers), dry weight (pyramid of biomass) or rate of energy flow (pyramid of energy) at successive trophic levels.

#6. Monosodium glutamate (MSG) in food is used as

Ans: (B)

Solution: Monosodium glutamate (MSG) is a flavor enhancer commonly added to Chinese food, canned vegetables, soups and processed meats.

#7. Which of the following disease is related to Corona virus?

Ans: (D)

Solution: All are related to Corona Virus.

#8. Which is not a type of secondary memory?

Ans: (C)

Solution: RAM is a primary Memory.

#9. What is XML stands for?

Ans: (B)

Solution: XML stands for extensible markup language. A markup language is a set of codes, or tags, that describes the text in a digital document. The most famous markup language is hypertext markup language (HTML), which is used to format Web pages.

#10. Microwaves are electromagnetic waves having frequencies in range of

Ans: (C)

Solution: Audible Range: 20 Hz to 20 KHz.
Ultra Sound: 20 KHz to 200 MHz.
Infra Sound: Less than 20 Hz.

Microwave frequencies range between 1 GHz to 1000 GHz.