Since, the environment refers to both physical and biological  conditions, it encompasses both living or biotic and  non-living or abiotic components of the earth.


 This component has living kingdom  in whole biosphere. i.e. plants, animals and microorganisms. The living organisms are interconnected with one another by various mechanisms and show interdependence on each other. These are primarily classified into different groups on the basis of their nutritional relationships.

On the basis of food they consume, the different living organisms we categorise into three groups. These are as follows:-

  1. PRODUCERS:  By the process of photosysnthesis  plants containg chlorophyll  produce  carbohydrate  like food , termed as producers. We also term them as autotrophs. These absorb radiant  energy of th sun and produce organic compounds like carbohydrates.  These convert solar energy into chemical energy and thus we term it as autotrophic, e.g. plants and blue-green algae. These green plants are sources are all biotic components of  ecosystem. They take up carbon di-oxide and release oxygen in turn into environment, thus balance the composition of air.
  2. CONSUMERS : These are dependent on producers for their  nutritional requirements and consume food prepared by producers. These animals we term as hetertrophs. We can further divide the consumers  into further  three categories like herbivores , omnivores etc:
  3. HERBIVORES: These are primary or first order  consumers which feed directly on the producers, i.e. plants, e.g. grazing animals like zebra, goat, horse, sheep etc. Omnivores also feed on plants along with flesh.
  4. CARNIVORES: These are the animals that feed on other animals. The carnivores which feed on herbivores are called second order consumers. Some carnivores may be predators like lions, hawks and wolves which attack and kill their prey and feed on their bodies. Some may be scavengers like jackals that feed on dead animals that they find. These we call third order consumers. After that level is omnivores.
  5. OMNIVORES: These that are animals feed on both plants and animals. Human and bears are omnivores. Crows are also termed as omnivores.
  6. DECOMPOSERS : These are microorganisms which feed on decaying and dead organic matter. It comes after omnivores. These breakdown the remains of dead animals and plants, to release various substances that can be used by other memebers of the ecosystem e.g.  bacteria and fungi. These are useful in decomposing  waste from ecosystem. These help in recycling of material, cleaning of waste and creating space for the growth of new organisms. If these organisms are removed from any ecosystem, rrecycling of nutrients will stop and balance in the ecosystem will be lost. Others animals like herbivores, carnivores,omnivores.


The abiotic components of an ecosystem are the non-living componenets on which living organisms are dependent. Each abiotic componenet influences the number and variety of plants and animal present in an ecosystem. This inturn influence the biodiversity of an area. Sun light, surrounding temperature, oxygen, carbon di-oxide, nitrogen and other atmospheric gases, wind etc.

  1. LIGHT : Light energy (sunlight) is the primary source of energy in nearly all ecosystem. It is used by green plants which contain chlorophyll.  Plants can do photosynthesis to produce carbohydrates with the help of abiotic components  like sunlight, carbon di-oxide, water.
  2. TEMPERATURE: Surrounding temperature helps in distribution of various types of plants and animals in definit places . The pattern of rain also affects the growth of the plant, which influences growth of various animals in different places.

3) ATMOSPHERIC GASES: Oxygen is required for respiration and carbon dioxide for photosynthesis. Atmospheric nitrogen is fixed in the soil by nitrogen fixing bacteria and available in the soil by lightening.

4)WIND: It helps in pollination and seed dispersal of some plants. It can remove and redistribution top soil, especially where vegetation has been reduced.

5)WATER:  It is essential  for life. According to the availability of water, growth of plants and  


 Living orgaism trasfers  food or energy  by different steps which we term as trophic level in food chain. The producers or autotrophs are present at the first trophic level. The producers are autottrophs which are present at the first trophic level.  Plant uses solar energy for photosynthesis, to make food. This food is useful for all consumers (herbivores to omnivores) directly or All consumerers like herbivores, omnivores use this various way. The herbivores or primary consumers we find at the second trophic level.  The third trophic level consists of small carnivores or secondary consumers like jackal. Fourth trophic level is large which we term as tertiary consumerers or omnivores.


It is a linear network of living organisms in a community through which energy is transferred in the form of food. It describes relationship of organisms about WHO EATS WHOM.


  1. Food chain involves the transfer of energy, materials and nutrients from producers to omnivores.
  2. The organisms of food chain serves as the vehicles of transfer of energy from one level to another till omnivores.
  3. The knowledge of food chain helps in understanding the feeding relationship as well as the interaction between herbivores to omnivores type of organisms in an ecosystem.
  4. It helps to understand the movement of toxic substances and the problems associated with biological magnification in the ecossytem.


Qs1: Why are crop fields known as artificial ecosystem?

Ans2: Artificial ecosystes are those ecosystems which are modified and managed by human beings. Crop field are man-made. Here plants do not grown by humans according to the season, type of soil etc. Crop fields are not like wild forest area, which is left is managed, soil is prepared for sowing seeds, then irrigated and further progress is also kept under observation for getting good yield. That is why, crop fields  we term as artificial ecosystem.

Qs2: We donot clean ponds or lakes, but an aquarium needs to be cleaned, why?

Ans2:  A pond or lake is a natural ecosytem. They are self-sustaining and complete. In them, all the organisms of food chain are availble. If any organism dies, there are microbes like bacteria and fungi to decompose their bodies into simpler substances.

 An aquarium, is an artificial and incomplete ecosystem.Abiotic componenets are not supplied naturally to it. It may not have all the biotic componemets in it. If a fish dies in an aquarium in the in the absence of decomposer, it will lie there as a rotten body, polliting the water of aquarium. Thus, an aquarium needs regular cleaning.

Qs3: Ozone layer absorbs which harmful radiation? Which causes ozone layer layer depletion?Which disease is caused by this ozone layer depletion?

Ans3:  Ozone  layer absorbs the harmful ultraviolet radiation.

 Emission of chlorofluorocarbons(CFCs)  from refrigertor, air conditioner causes  ozone layer depletion. Ozone layer depletion may lead to skin cancer in human beings.

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