Q. With reference to food chains in ecosystems, consider the following statements:
- A food chain illustrates the order in which a chain of organisms feed upon each other
- Food chains are found within the populations of a species
- A food chain illustrates the numbers of each organism which are eaten by others
Which of the statements given above is/are correct?
- 1 only
- 1 and 2 only
- 1, 2 and 3
- None
Answer: (a) 1 only
Food Chain
- Transfer of food energy from green plants (producers) through a series of organisms with repeated eating and being eaten link is called a food chain.
- E.g. Grasses → Grasshopper → Frog → Snake → Hawk/Eagle.
- Each step in the food chain is called a trophic level.
- A food chain starts with producers and ends with top carnivores.
- The trophic level of an organism is the position it occupies in a food chain.
- A food chain illustrates the order in which a chain of organisms feeds upon each other.
- Food chains are not found within the populations of ‘a’ species, because technically, Food chain is the sequence of organisms through which the energy flows. If the species starts eating itself, then flow of energy will not proceed – Hence statement 2 is not correct.)
- Food chain doesn’t show “numbers” of each organism eaten by others, (food web illustrates the number, not the food chain).
Food Web
- Multiple interlinked food chains make a food web.
- Food web represents all the possible paths of energy flow in an ecosystem.
- If any of the intermediate food chains is removed, the succeeding links of the chain will be affected largely.
- The food web provides more than one alternative for food to most of the organisms in an ecosystem and therefore increases their chance of survival.
