Food Chain and Food web

This is a presentation for the topic "Food Chains and Food Web"

1. FOOD CHAINS AND FOOD WEBS

2. What forms a Food Chain? The series of organisms taking part at various biotic levels form a food chain. – Food Chain in nature in forests . - Food Chain in nature in grasslands . - Food Chain in nature in ponds .

3. Levels of a Food Chain Each step or a level of a food chain forms a trophic level.

4. Flow of energy!! Interactions among various components of our environment involves flow of energy from one component of system to the another . Autotrophs capture the energy present in sunlight and convert it into chemical energy. This energy supports all activities of the living world. This energy from autotrophs flow to heterotrophs and decomposers. We know that during flow of energy some amount of energy is lost in environment. Fact:- Flow of energy is unidirectional.

5. The flow of energy between the various components of the system has been extensively studied and it has been found that: The plants capture about 1% of the total sunlight that falls on their leaves, and further they convert this energy into chemical energy. When plants are eaten by primary consumer only 10% of the energy produced by the plants is available for the consumer. In this manner at every level only 10% of the energy is made available for the next trophic level. There are generally greater number of individuals at lower levels of food chain. BONUS QUESTION:- Why do food chains generally consist of only 3-4 steps? Answer: Since very little amount of energy is available for the next level of consumers food chains are generally of 3-4 steps.

6. Food Web Each organism is eaten by two or more type of organisms which in turn are eaten by several other organisms. So instead of a straight food chain ,relationship can be shown by series of branching lines known as food web.

7. Biological Magnification Unknowingly many harmful chemicals enter our bodies through food chain. Several pesticides get absorbed by the plants through soil, water. These chemicals are not degradable and therefore get accumulated at each trophic level. As humans are at top of the food chain maximum concentration of such chemicals accumulate in our body. This phenomenon is know as biological magnification.