Biosphere and levels in Biosphere



A thin layer of atmosphere in which all living organisms exist is called biosphere.


Sum of all the ecosystems. Organisms within the biosphere are adapted to the environment. These organisms also interact to modify and control chemical and physical conditions of the biosphere. An organism lives in its habitat. An organism responds to a variety of environmental factors.

When all the environmental factors are within the range of its tolerance, then organism can inhabit a location.


Biosphere is characterized by two terms:

  1. Habitat
  2. Ecological niche

1. Habitat:

The place where an organism lives is called its habitat.

Habitat may be:

  • Aquatic
  • Terrestrial

Aquatic habitat may be:

  • Fresh water
  • Marine

2. Ecological niche:

The basic role or profession of an organism in a community is called ecological niche.
The niche is particularly concerned with the:

  • Feeding habits
  • The roles of a particular species within an ecosystem.
  • All aspects of its interaction with the living and nonliving environment.

Ecological niche within a habitat also specifies:

  • Environment factors necessary for survival like How the organism gets its supply of energy and materials.
  • Organism behavior and its interactions in environment
  • Niche also includes all the physical
    • Temperature range
    • Humidity range
    • pH of water
    • pH of soil

Level in Biosphere

There are 5 different levels in Biosphere which are these:

  1. Organism ecology
  2. Population
  3. Community
  4. Biomes
  5. Ecosystem

1. Organism Ecology

It is also called autecology.

It is concerned with:

  • Behavioral ways
  • Physiological ways
  • Morphological ways

Each organism has certain limits of tolerance. These limits determine the habitat of the organism.


The group of interbreeding individuals belonging to same species and living in a common geographic is called population.
The populations of plants and animals do not function independently in an ecosystem.
Some populations compete with other populations for resources such as food, water and space.
In some cases, one population is the food resource for another.
Two populations may mutually benefit each other.
A population can be described in term of member, growth rate and age distribution.


All populations within an ecosystem are known as community.
The populations in a community are interconnected to one another.
The individuals of these populations interact among themselves and with individuals of other species to form a community.
These interactions are:

  • Predation
  • Competition
  • Parasitism
  • Commensalism
  • Mutualism
  • Grazing


The major regional ecological communities of plants and animals are called biomes.
Each biome consists of different combinations of plants and animals.
These plants and animals are fully developed to form climax community.
Each biome is characterized by a uniform life form of vegetation such as grass or coniferous trees.

Major Terrestrial Biome:

There are six major terrestrial biomes:

  • Forest
  • Grassland
  • Woodland
  • Shrubland
  • Semi shrub desert
  • Desert


Sum of all the communities.


A biological community together with the associated abiotic environment is called ecosystem.
The ecosystem is a major unit of ecology.
Organisms interact with their environment within an ecosystem.
The study of ecosystem includes

  • Energy flow between biotic and abiotic components.
  • Cycling of chemicals between biotic and abiotic components.



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