Biosphere

 Abiotic factors are also essential for the existence of theliving world which comprises of animals, plants andmicroorganisms. How are abiotic factors useful to bioticfactors?Discuss and complete the illustration given below suitably

Sun is the primary source of energy in the living world.Green plants convert light energy to chemical energythrough photosynthesis.This energy gets transferred to other organisms throughfood chain. Plants that perform photosynthesis are calledproducers while organisms that depend on plants directlyor indirectly for food are called consumers. The consumersthat directly depend on plants are called primaryconsumers. Organisms that feed on primary consumers arecalled secondary consumers. Organisms that feed onsecondary consumers are called tertiary consumers.You are already familiar with the food web that illustratesfood relations in nature.Observe the illustration of a food web.With the help of the indicators, discuss and write down theinferences

ndicators

  

 How do food chain and food web differ from each other? 

 

 Is a single organism involved in more than one food chain?

 

Is the possibility of an organism becoming food to morethan one organism helpful to the existence of the food chain?Why? 

 How does the variation in the number of a particularorganism in the food chain affect the existence of otherorganisms 

Did you read the note on trophic level?Complete the illustration by including the organisms ofthe food web at various trophic levels.

ndicators 

Does the same organism occupy more than onetrophic level?

 Is there any possibility of a fifth trophic level? 

How does the elimination of organisms from thehigher trophic levels affect the ecosystem?Examine the food chains taken from the illustration 13.2.1.Grass  

 Rabbit  Eagle2.Grass 

  Grasshopper  

 Calotes  

 Eagle3.Grass 

  Grasshopper  

 Frog  

 Snake  

 EagleFind out the trophic levels represented by the eagle inthese food chains. Write them down in the science diary.The number of trophic levels and the position oforganisms in the trophic levels of the ecosystem is notconstant. It changes in accordance with the complexityand the length of the food chain  

Ecological interactions

Observe the illustration of some ecological interactions.

Complete the illustration given below with suitable examples forecological interactions

There are many interactions in nature that we do not see or realise.These interactions maintain the balance and stability of the ecosystems.Food relations are visible instances of interaction among organisms

The ecosystem becomes more stable as the diversity of ecologicalinteractions and abiotic factors increases.Diverse ecosystemsObserve the pictures given below