Basin concepts of environment and ecology Tnpsc

Environment and Ecology

The environment is the condition in which we live, work etc. It is the natural world for example the land, air, and water in which animals, humans, plants etc live.

Ecology is the study of organisms and how these organisms interact with the environment around them. It studies the relationship between living things and their habitats.

Types of Ecology

The different levels of ecology are:

  • Organisms
  • Communities
  • Population
  • Ecosystem

Also can be classified as landscape ecology, behavioural ecology and population ecology. To know what the Biosphere is? To study the components, functions, and biodiversity of the ecosystem.

Learn about major biomes and the conservation of biomes. The biosphere is the life-supporting layer of the earth. This layer consists of the Lithosphere, Atmosphere, and Hydrosphere. It includes flora and fauna.

The range of the biosphere is approximately 20 km high from the surface of the sea to the troposphere. Most plants live in a very narrow part of about 1 km above and below the mean sea level (MSL).The biosphere is made up of various biomes and ecosystems. All living things are grouped called Species, irrespective of their numbers.

The area in which plants, animals, and microbes live is called Habitat. A variety of flora and fauna live in a particular habitat called Biodiversity.

Environment and Ecology - Verticle range of biosphere on earth
The vertical range of the biosphere, where life is supported in the Tallest mountains at 8000* meters to the deepest part of the ocean

1. Ecosystem

An Ecosystem is a community, where all living organism has a life and interact with one another and also with the non-living environment such as land, soil, air, water, etc.It ranges from a small unit such as the bark of a tree or ecosphere, for example, Cropland, Pond, Desert, forest, etc.

A biosphere consists of all ecosystems and sustains life forms including Humans.

Environment and Ecology
An ecosystem is a community where all living and nonliving things interact and sustain life

1.1 Components of the Environment and Ecology or Ecosystem

It consists of Biotic, Abiotic, and Energy Components.

a. Abiotic Components

All on-living things such as land, water, calcium, inorganic, physical, and chemical factors in the environment.

b. Biotic Components

All living things such as plants, animals, and microbes. Biotic Components are divided into three categories: Producers, Autotrophs, and Consumers.


Prepares its food, and self-nourishing components and are called Autotrophs. These can be found on both water and land. Examples: Plants, Algae, Bacteria, etc.


Those that consume the producer for nourishment directly or indirectly. These cannot produce their food. Also called Heterotrophs.

The consumer is divided into four main categories namely Primary consumers, Secondary consumers, Tertiary consumers, and Decomposers.

Primary consumers

These directly consume the Producers. Generally, these are herbivorous such as goats, Cows, etc.

Secondary Consumers

These consume the herbivorous, called carnivorous. Eg. Lion, Snake, etc.

Tertiary consumers

These are top carnivores that consume both herbivores and carnivores. Eg: Owl, Crocodile, etc.


Some organisms that are incapable of producing their food live on dead and decaying plants and animals. These are called Saprotrophs. Eg. fungi, Mushrooms, etc.

c. Energy Components

The Sun is the ultimate source of energy. The energy from the Sun gets transformed into other forms of energy through the various components in the ecosystem.

The producers, consumers, and decomposers contribute a lot to the energy flow in the ecosystem.

1.2 Functions of an Environment and Ecology and Food Chain

The living organism forms an interacting set of flora and fauna which are organized into various trophic levels, food chains, and food webs. The pattern of energy flow affects the functioning of the ecosystem.

The distribution and circulation of organic and inorganic matter in the ecosystem depend on the pattern of energy flow. Energy flow commonly takes place in a systematic order in an ecosystem through various levels called Tropic Levels.

The chain of the flow of energy from one group of an organism to another via various trophic levels is called a Food Chain. A system of interlocking and interdependent food chains is called a Food Web.

Environment and Ecology - Food chain and Food Web
Illustration of Food chain and Food Web in the ecosystem

2. Biodiversity

Biodiversity or biological diversity refers to a wide range of living organisms that exist in a habitat. Biodiversity is highly dependent on topography, climate, and human activities.

It also represents the strength of the biological resources of the earth.

In biodiversity, each species has an important role to play in the ecosystem irrespective of its size or number. It maintains ecological balance and adds social benefits such as education, research, etc over the area.

2.1 Loss of Biodiversity

The extinction of flora and fauna due to human and natural influences is called Loss of Biodiversity. It has a great impact on the Environment and Ecology and that includes mankind. It also affects land, water, etc.

Habitat destruction caused by population explosions, pollution, deforestation, and global warming is the most common causes of Loss of Biodiversity.

As a result of the Loss of Habitat, sometimes the species is permanently eliminated from the earth. A good ecosystem is one that provides clean water, good soil, food, etc. Hence a stable biosphere has to be conserved.

An ecological region where it has lost more than 70% of its original habitat is considered a Hotspot. Hotspots in India are the Indo-Burma Region, Sundaland, the Himalayas, and the Western Ghats.

3. Biomes

It is an ecosystem where all the plants and animals are collectively found in a geographically extensive area.

Biomes are defined by abiotic things such as relief, climate, soils, and vegetation. They are divided into Terrestrial Biomes and Aquatic biomes.

3.1 Terrestrial Biomes

It is a group of living organisms that live and interact with each other on land. These are determined by rainfall and temperature. Some major terrestrial biomes are Tropical Forest, Tropical Savanna, Desert, Temperate Grassland, and Tundra.

3.1.1 Tropical Forest Biomes

Environment and Ecology - Tropical Forest Biomes
Tropical Forest Includes Evergreen Rainforest, Seasonal Deciduous Forest

Tropic forest consists of several sub-biomes such as evergreen rainforest, seasonal deciduous forest, etc. This biome ranges between 10° N and 10° S of the Equator. About half of the world’s tropical forest lies in Central and South America.

The climate shows little seasonal change with high annual rainfall and relatively constant, high temperatures. This unique weather favours a thick vegetative cover.

These forests have the highest biodiversity and primary productivity of any terrestrial biomes. The Indonesian Islands, Amazon Basin, and Congo Basin are the major regions of Tropical forests.

These regions have very dense forests and human settlements are scattered. Due to the humid nature of this biome, people get affected by tropical diseases such as Malaria, Yellow fever, etc.

The people of this biome live through food gathering, fishing, lumbering, and shifting cultivation. The main trees found in this biome are Rubber, Bamboo, ebony, etc.

Elephants, monkeys, pheasants, bats, jaguars, etc are important birds and animals.

The U.S National Cancer Institute found that 70% of plants for treating cancer are found only in rainforests. Eg. Lapacho.

3.1.2 Tropical Savanna food web (Grasslands) Biomes

Environment and Ecology - Tropical savanna grassland biomes
Savanna Grassland, where grass grows tall and sharp

Tropical grassland is found between tropical forests and deserts. The tropical Savanna or tropical grassland food web or biome is found between 10° to 20 ° N and S latitudes. These grasslands are generally flat and are found in the Sahel, south of the Sahara in East Africa and in Australia.

This biome is generally hot and dry and experiences moderate to low rainfall. As a result, the grass grows tall and sharp. The chief occupation of people is herding. The people here are basically nomadic. Savanna’s desert food web is characterized by grasses and trees spread over the grasslands.

The animals found here are lions, Leopards, tigers, deer, zebras, giraffes, etc. Flora like Rhodes grass, red oats grass, lemongrass, etc. Tertiary consumers in the savanna are Lions, Leopards, Cheetahs, Hyenas, Jackals, Wild dogs, snakes, etc.

3.1.3 Desert Biomes

Environment and Ecology - Desert Biomes
Xerophytes a special type of vegetation in deserts

Deserts are usually found on the western margin of the continent between 20° and 30° N and S latitudes. The annual rainfall is less than 25 cm.

Due to a lack of rainfall and arid conditions, these areas do not possess any vegetation but have a special vegetation type called Xerophytes. The soil is sandy and saline, the deserts are agriculturally not fit.

Drought-resistant thorny shrubs and bushes, palms are found in deserts. Tribal people gather food and practice hunting. They move frequently in search of pastures and their temporary settlements.

Transportation is done by camels. Reptiles like snakes, lizards, and scorpions are commonly found. Oasis is fertile fresh water, found in deserts and semi-arid regions. These are fed by springs.

Dates, figs, palms, citrus fruits, maize etc are cultivated near oases.

3.1.4 Temperate Grassland Biomes

Environment and Ecology - Temperate Grassland Biomes
Temperate grasslands depend upon precipitation

Temperate grasslands found in the interior of the continents are characterized by large seasonal variations. It has warm summers and cool winters. These grasslands strongly depend on precipitation. If there is higher precipitation it leads to tall and soft grass.

If there is lower precipitation it leads to short and soft grass. These regions are good for wheat cultivation. Due to the lack of farm labour, mechanized agriculture is practised.

The pastoral industry is the main source of occupation, animal slaughtering, meat, and dairy products, etc are industries here. Grasshoppers, wolves, bison, and prairie dogs are common in these areas. Temperate Grasslands are called by different names in different parts of the world.

Prairies- North America

Steppes- Eurasia

Pampas -Argentina and Uruguay

Veld- South Africa

Down- Australia and New Zealand

3.1.5 Tundra Biomes

Environment and Ecology - Tundra Biomes
Tundra Biomes are frozen ground in the Arctic, Antarctic and Greenland

These are vast lowlands where the ground remains frozen. Northern parts of Asia, Canada, Europe, Greenland, the Arctic, and Antarctic regions fall in this biome. These regions are also called Barren Lands. Tundra experiences long severe winters and short cool summers.

Due to continued low temperatures and short growing seasons, the net primary productivity is very low. People are nomadic and their major occupation is fishing and hunting. There is a sparse population and they change their settlement frequently due to harsh weather.

People live in igloos in winter and tents in summer. Arctic moss, Arctic willow, and lichens are grown here. Polar bears, wolverines, reindeer, and snowy owls are found here.

3.2 Aquatic Biomes

These living organisms interact with each other and live in an aquatic environment. Similar to terrestrial biomes, aquatic biomes are influenced by a series of abiotic factors. It is classified into Freshwater biomes and marine biomes.

Fresh Water Biomes

It consists of lakes, ponds, rivers, streams, wetlands, etc. Influenced by the volume of water, the composition of oxygen, water flow, temperature, etc. Human depends on freshwater for drinking, agriculture, etc. A common plant in freshwater is Lily, lotus, duckweed, etc.

Salmon, turtles, crocodiles, and trout are common animals in freshwater.

Marine Biomes

It is the largest and most continuous body of salt water and provides a wide range of habitats. Coral reefs are the second kind of marine biomes. Coastal areas and estuaries are areas where saltwater and freshwater mix which forms the third biome.

The nutrients are circulated more quickly to marine organisms, and water provides maximum mobility to the organisms. Kelp, phytoplankton, algae, etc grow in marine water. Marine is an important source of food for humans, animals, and plants.

Problems for marine biomes are pollution, overfishing, and a rise in sea level.

Scientist created artificial biosphere in Arizona, America called as Biosphere-2


The primary cause of loss of biodiversity is habitat alteration caused by humans. The increasing human population leads to the overexploitation of biological resources. Most places are heavily threatened by a human. It is the duty, of everyone, to preserve it.

Environment and Ecology - gulf of mannar biosphere
Gulf of Mannar biosphere


The biosphere includes Biotic and Abiotic components. The biotic component depends on other biotic components for food and nutrition. These together form an ecology. The transfer of nutrients from one level to another is explained through the Food chain and the food web.

The extensive ecosystem called Biomes and its type were noted with respect to the people, occupation, flora, and fauna. Also, the conservation of the biosphere is discussed.

What are your thoughts on conservation and how to protect the environment for the future?

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* * All the Notes in this blog, are referred from Tamil Nadu State Board Books and Samacheer Kalvi Books. Kindly check with the original Tamil Nadu state board books and Ncert Books.
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