Our Environment II Ecosystem and Environment II Components of Ecosystem II Food Chain and its types II Types of Ecosystems II CBSE Notes II Ncert Notes II Free study material

The surroundings where an organism live, survive and reproduce is called as ENVIRONMENT.

A community where Biotic and Abiotic components are there and interact with each other is called as ECOSYSTEM.

COMPONENTS OF ECOSYSTEM:

TYPES OF ECOSYSTEMS:

Manmade: Gardens and Crop-fields are human made (artificial) ecosystems

Natural:  Forests, Ponds and Lakes

According to the manner in which they obtain their sustenance from the environment organisms can be grouped as producers, consumers and decomposers.

Producers: Organisms which can make organic compounds like sugar and starch from inorganic substances using the radiant energy of the Sun in the presence of chlorophyll are called the producers.

All green plants and certain bacteria come under this category.

Consumers: Organisms which depend on the producers either directly or indirectly for their sustenance and consume the food produced may be directly from producers.

They also obtain food indirectly by feeding on other consumers are the consumers.

Consumers can be classed variously as herbivores, carnivores, omnivores and parasites

Herbivores include Deer, Grasshopper etc.

Carnivores include Frog, Fish, Tiger etc.

Omnivores include Beer, Owl, Humans etc.

Decomposers: The organisms which break-down the complex organic substances into simple inorganic substances by microorganisms including bacteria and fungi (break-down the dead remains and waste products of organisms)

The simple inorganic substances go into the soil and are used up once more by the plants.

FOOD CHAIN

The sequence of Living Organisms in a community in which one organism consumes another to transfer food and energy is called as Food Chain.

In the above example Grass->Deer->Lion are the sequence of organisms in which Grass is eaten up by deer, deer is eaten up by lion to transfer food and energy.

It is a series of organisms feeding on one another.

Characteristics of Food Chain:

It is always Straight.

It shows relationship among various components of ecosystem.

It helps us to understand concept of Flow of energy.

Biological Magnification can be easily understood by studying particular Food chain.

EXAMPLES:

In Forest Ecosystem:

In Aquatic Ecosystem:

In the above food chain of Aquatic Ecosystem 

PRODUCERS are Aquatic Plants

Primary CONSUMERS are Aquatic Insects

Secondary CONSUMERS are Small Fishes

Tertiary CONSUMERS are Big Fish 

WHAT ARE TROPHIC LEVELS?

The various steps "OR" Levels of the Food are called as Trophic Levels.

 The autotrophs or the producers are at the first trophic level. Their role is to fix up the solar energy and make it available for heterotrophs or the consumers.

The herbivores or the primary consumers come at the second.

Small carnivores or the secondary consumers at the third.

Larger carnivores or the tertiary consumers form the fourth trophic level.

Thus, the series of organisms feeding on one another. The food we eat acts as a fuel to provide us energy to do work. So, interactions among various components of the environment involves flow of energy from one component of the system to another.

The flow of energy:

In a Food Chain the energy flows from one component to another and some energy is lost to the environment in forms which cannot be used again, This is called as Flow of Energy.

The green plants in a terrestrial ecosystem capture about 1% of the energy of sunlight that falls on their leaves and convert it into food energy.

When green plants are eaten by primary consumers, a great deal of energy is lost as heat to the environment, some amount goes into digestion and in doing work and the rest goes towards growth and reproduction. 

An average of 10% of the food eaten is turned into its own body and made available for the next level of consumers.

10% can be taken as the average value for the amount of organic matter that is present at each step and reaches the next level.

Since so little energy is available for the next level of consumers, food chains generally consist of only three or four steps.

 The length and complexity of food chains vary greatly.

The flow of energy is always Unidirectional. The energy that is captured by the autotrophs does not revert back to the solar input and the energy which passes to the herbivores.

Secondly, the energy available at each trophic level gets diminished progressively due to loss of energy at each level.

FOOD WEB 

The series of organisms feeding on one another is called as Food Web.

Each organism is generally eaten by two or more other kinds of organisms which in turn are eaten by several other organisms.

BIOLOGICAL MAGNIFICATION

The concentration of harmful chemicals increases with every next trophic level in food chain and the maximum concentration of these chemicals get accumulated in our bodies Humans (as we occupy top of food chain). This phenomenon is known as biological magnification.

This is the reason why our food grains such as wheat and rice, vegetables and fruits, and even meat, contain varying amounts of pesticide residues. 

They cannot always be removed by washing or other means.