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TNPSC Geography Free Notes – Biosphere & Hydrosphere

இந்தக் கட்டுரையில், TNPSC குரூப் 1, குரூப் 2, குரூப் 2A, குரூப் 4 மாநிலப் போட்டித் தேர்வுகளான TNUSRB, TRB, TET, TNEB போன்றவற்றுக்கான  முறைகள் இலவசக் குறிப்புகளைப் பெறுவீர்கள்.தேர்வுக்கு தயாராவோர் இங்குள்ள பாடக்குறிப்புகளை படித்து பயன்பெற வாழ்த்துகிறோம்.

Biosphere & Hydrosphere

Distribution of Land and Water in the Earth
 Earth is covered by land and water.
 About 70.8% of covered by water and 29.2% of its area by land.
Fresh water
Fresh water is defined as water with a salinity of less than 1% compared to that of the
 River Nile has its source near Lake Victoria in Uganda. The Nile River in Africa is the
longest river in the world
 The river Amazon in South America is the second longest river.
 The Yangtze River, which flows in China, is the longest river in Asia and the third longest
river in the world.
 The longest river system in the United States, the Mississippi-Missouri system is
considered the fourth longest river in the world.
 263 rivers either cross or demarcate international political boundaries.
 Lake Baikal is the deepest freshwater lake in the world.
 Caspian Sea is the largest saltwater lake in the world
 Chilika Lake is the largest lagoon lake in India.
 Sambhar Lake in Rajasthan is the largest saltwater lake in India.
 Finland is known as land of thousand lakes.
 Marshes are shallow wetlands around lakes, streams, or the ocean where grasses and
reeds are common, without trees.
 Rann of Kutch in India is a salt marsh

 A swamp is a wetland with lush trees and vines found in a low-lying area beside slow
moving rivers
 Pallikaranai wetland is a fresh water swamp adjacent to the Bay of Bengal situated in
the southern part of Chennai.
 Sea is a body of saline water (generally a division of the world ocean) partly or fully
enclosed by land.
 Andaman Sea, Arabian Sea, Bay of Bengal, Java Sea, Persian Gulf and Red Sea are
marginal seas of the Indian Ocean.
Water body surrounded on three sides by land and the fourth side (mouth) wide open
towards an ocean.
Large body of water, with a narrow mouth, that is almost completely surrounded by
Narrow channel of water, connecting two larger bodies of water. Palk Strait connects
Gulf of Mannar and Bay of Bengal.
Enclosed seas
 Seas that reach very deep into the continent stay connected with one or the other
ocean of the world through straits.
 The Caribbean Sea is a perfect example.
Landlocked sea:
 It is surrounded by land on all sides without any natural opening. The Dead Sea and the
Caspian Sea are the best examples of this.
 Fjord is a long indented bay with steep slope that has been created by the submergence
of U shaped glacial valley. Example: sogne Fjord in Norway (205 km).
 Ria is an indented bay with gradual slope formed by the submergence of V shaped river
valley. George River in Sydney is the best example for Ria.

The Pacific Ocean
 Pacific Ocean is the largest ocean in the world
 Portuguese explorer Ferdinand Magellan in 1521 named the ocean Pacific Ocean
meaning ‘peaceful’
The Atlantic Ocean
The Atlantic Ocean’s name refers to Atlas of Greek mythology.
The Indian Ocean
The Indian Ocean is the third-largest in the world. It is named after India.
The Southern Ocean (Antarctic Ocean
The Southern Ocean is the world’s fourth largest ocean. The Southern Ocean is the
youngest ocean
The Arctic Ocean
The Arctic Ocean is shallower and smaller than the other four ocean
Relief of the ocean floor
The ocean basins are characterised by the following major relief features:
 Continental shelf
 Continental slope
 Continental rise
 Deep sea plain or Abyssal plain

 Oceanic deep
 Oceanic ridge
Continental Shelf
 They are shallower, thus enables sunlight to penetrate through the water.
 This encourages abundant growth of grass, sea weeds and plankton. Hence these zones
become the richest fishing grounds in the world.
 Eg. The Grand Banks of Newfoundland.
Continental Slope
 The most important characteristic of continental slope is the presence of deep canyons
and trenches.
 Due to the low penetration of sunlight, the slope has nearly freezing temperature.
Continental Rise
 This underwater feature found between continental slope and abyssal plains is called
the continental rise.
 It consists of submarine fans which are similar to the alluvial fans found on land
Deep Sea Plains or Abyssal Plains
 The deep sea plains or abyssal plains are underwater plains found on the deep ocean
 These are often characterized by features like abyssal hills, sea mounts, guyots, coral,
atoll etc.
Oceanic Deeps
Trenches are the deepest part of the oceans and occupy about 7% of the total relief of
the ocean floor.
Oceanic Ridge
Two of the most well known mid-ocean ridges are the Mid-Atlantic Ridge and the East
Pacific Ridge.
Movement of the Ocean

 Sea waves are ripples on water caused when winds blow over the sea.
 The height of these waves depends on the speed of wind
 The periodic rise and fall of sea water due to the gravitational pull of the sun and moon
on earth are called tides.
 They are classified broadly into Spring tides and Neap tides.
Ocean Currents
 The movement of oceanic water on the surface and at the depths in a definite direction
is called ocean current.
 Ocean currents are in clockwise motion in the northern hemisphere and in the anti-
clockwise motion in the southern hemisphere.
 On the basis of temperature, ocean currents are classified as warm currents and cold
The factors that generate ocean currents are:
 Earth’s rotation
 Prevailing winds and
 Differences in temperature and salinity of ocean water.
An ecosystem is a community, where all living organisms live and interact with one
another and also with their non-living environment such as land, soil, air, water etc
Components of Ecosystem
An ecosystem consists of three basic components, namely
 Abiotic components
 Biotic components and
 Energy component
Abiotic Components
 Abiotic components include the non-living, inorganic, physical and chemical factors in
the environment.
 Eg. Land, Air, Water, Calcium, Iron etc.

Biotic Components
 Biotic components include plants, animals and micro organisms.
 Biotic components can be classified into three categories :
 Producers
 Consumers
 Decomposers
 Producers are self nourishing components of the ecosystem.
 Hence they are called Autotrophs.
 They are found both on land and water. Eg. Plants, Algae, Bacteria etc.
 Consumers are those that depend on producers, directly or indirectly.
 Hence they are called Heterotrophs.
 The common category of consumers are:
 Primary consumers. Eg. zebra, goat etc.
 Secondary consumers. Eg. lion, snake etc.
 Tertiary consumers Eg. owl, crocodile etc.

 They live on dead and decaying plants and animals.
 Hence they are called Saprotrophs.
 Eg: Fungus, Mushrooms etc.

Energy Components
 All organisms in the biosphere use energy to work and convert one form of energy into
 The Sun is the ultimate source of energy for the biosphere as a whole.
 An ecosystem consists of a biological community and an abiotic environment.
 An ecosystem becomes a biome when it extends over a large area.
Types of Biomes
 World Biomes are mega ecosystems existing and operating over large areas
 Biomes are classified into two major groups such as Aquatic biomes and Terrestrial
 Wetlands are transition zones between aquatic and terrestrial biomes
Aquatic Biomes
 The aquatic biomes are the most important of all the biomes as, the water forms the
vital resource and is essential for any life form.
 Aquatic Biome is further divided into:
1. Fresh Water Biome
2. Marine Biome
Terrestrial Biome
 Terrestrial biomes are very large ecosystems over land and they vary according to
latitude and climate.
 They are broadly divided into eight types
1. Tropical Evergreen Rain Forest Biome
2. Tropical deciduous Forest (Monsoon Forest) Biome
3. Temperate Deciduous Forest Biome
4. Tropical Grassland Biome or Savanna Biome
5. Temperate Grassland Biome
6. Tropical Desert Biome
7. Taiga or Boreal Forest Biome
8. Tundra Biome
Tropic Temperate

 Llanos -Columbia &Venezula
 Campos -Brazil
 Savanna -Africa
Temperate grasslands are called differently in different parts of the world.
 Prairies — North America
 Steppes — Eurasia
 Pampas — Argentina and Uruguay
 Veld — South Africa
 Downs — Australia
 Canterburg — Newzealand
 Manchurian — China
Tropical Desert Biomes
 Sahara desert, Arabian desert Thar deserts
 Berbers – Africa
 Bedoiuns– Arebia
 Damara – Namibia
 Bushman – Kalahari Desert
 Aborigines – Australia
 Taiga & Tundra Biome
Biodiversity can be identified at three levels:
 Genetic diversity
 Species diversity
 Ecosystem diversity
Biodiversity hotspots
Biodiversity hotspots of the World – 34 in 17 countries
Endangered species
 International Union for Conservation of Nature (IUCN) 1964
 IUCN – country office in Delhi, India 2007
Biodiversity conservation in India

 Project Tiger, 1973
 Operation Crocodile, 1975
 Project Rhinoceros, 1987
 Project Elephant, 1992
 Project Sea Turtle, 1999
 Environment Protection Act, 1986


Tamilnadu mega pack
Tamilnadu mega pack
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