General Awareness play a vital role in all  Examination. we can expect  Questions from different Topics.In Banking and other competitive exams like RRB, CDS, LIC AO, RBI, SSC, UPSC, FCI, UIIC, OICL, SBI Clerks and PO the questions on  Structure and Composition of Biosphere  are being asked. Here we have given Geography study notes on ” Structure and Composition of Biosphere “ for SSC CGL Examinations 2019-20 & other examination. Candidates those who are all preparing for the Examination can use this study material.


Biosphere refers to the narrow zone of the earth in which all life forms exist . this is the zone in which all the three essentials things which are required for susteinance of life are found in a right mixture. They are land (lithosphere), air (atmosphere) and water (hydrosphere). In other words, this narrow zone is a place where lithosphere, atmosphere and hydrosphere meet .


Biosphere has three basic components. These are

(A) abiotic (physical and inorganic) components;

(B) biotic (organic) components and

(C) energy components.

Let us discuss about these three components in detail.

(A) Abiotic Components: These components broadly consist of all non-living elements which are essential for the survival of all living organisms. These are :-

(i) lithosphere (solid part of the earth crust),

(ii) atmosphere and

(iii) hydrosphere.

Mineral nutrients, certain gases and water are the three basic requirements of organic life. Soils and sediments constitute the chief reservoir of mineral nutrients. Atmosphere constitutes the chief reservoir of gases essential for organic life. Ocean consitutes the chief reservoir of liquid water. where all these three reservoirs intermingle and that area becomes the most fertile area for organic life. The upper layer of the soil and shallow parts of the ocean constitute the most important areas, box sustaining organic life.

The upper layer of soil, permits easy penetration of gases and percolation of moisture, while shallow parts of oceans, allow penetration of sunlight, intermingling of dissolved gases and nutrients from land surface and ocean bottoms.

(B) Biotic Components: Plants, animals and human beings including microorganisms constitute the three biotic components of environment. In a way these can be called as the three sub-systems.

(i) Plants: Plants are most important among biotic components. They are the only primary producers as they produce their own food through the process of photo synthesis and hence are called autotrophs. Not only plants alone produce all kinds of organic matter but also help in cycling and recycling of organic matters and nutrients. Thus, plants are the major source of food as well as energy for all organisms.

(ii) Animals: While plants are the primary producers, the animals are the main consumers. Therefore, animals are heterotrophs. There are three main functions of animals:

(a) to use organic matter made available by plants as food.

(b) to transform the food into energy and

(c) to utilise the energy for growth and development.

(iii)Micro-organism: They act as decomposers of dead plants and animals.

(C) Energy: This is the third and vital component of the biosphere without which life could not have been possible on this planet. It is essential for generation and reproduction of all biological life on this planet. All organisms in the
biosphere are like machines which use energy to work and also to convert one form of energy into another. Sun is the major source of energy without which we can not think about the existence of the biosphere.

Structure and composition of Biosphere

Ecological System: Interactions of a particular group of organisms with abiotic factors within a particular habitat resulting in particular habitat resulting in clearly defined energy flows and material cycles on land, water & air.

Ecology: Derived from Greek word ‘oikos’ meaning house and ‘logy’ means science. Ernst Haeckel used the term in 1869 for the first time. The study of interactions between life forms and physical environment is known as science of ecology. So, it is the study of abiotic and biotic interactions.

Habitat: It is the totality of physical and chemical factors that constitute the general environment.

Ecosystem: System of biotic and abiotic components inter-related and interact with each. Therefore, an ecosystem involves interactions among different components and flow of energy among these components.

Ecological adaptation: Plants and animals species have got adapted through evolution to different types of environmental conditions.



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