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Question
What is ten per cent law? Explain with an example.
Solution
According to the 10 per cent law, only 10 per cent of the energy entering a particular trophic level of organisms is available for transfer to the next higher trophic level.
In the following food chain, only 10 per cent of energy is transferred to the next trophic level. The flow of energy is shown below.
Plants → Grasshopper → Frog → Snake → Hawk
100,000J 10,000J 1,000J 100J 10J
When the energy available at the producer level is 100,000 J, only 10 J of energy is available to the hawk.
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RELATED QUESTIONS
Why are green plants called producers?
What is biological magnification?
Organisms of a higher trophic level which feed on several types of organisms belonging to a number of lower trophic levels constitute the ______.
A food chain occurring in the sea which provides food for many people can be written as :
phytoplankton → zooplankton → X → Y
What could be X?
Match the terms given in column I with the terms given in column II and column III having the same meaning :
| Column I | Column II | Column III |
| (1) Secondary consumer | Herbivore | 1st trophic level |
| (2) Primary consume | Autotroph | 3rd trophic level |
| (3) Producer | Carnivore | 4th trophic level |
| (4) Tertiary consumer | Large carnivore | 2nd trophic level |
Consider the following food chain
(i) Plants → Mice → Snakes → Hawks
(ii) Plants → Mice →Hawks
If energy available at the producer level in both the food chains is 100 J, in which case will hawks get more energy as food and by how much? Justify your answer.:
A food chain comprises of cat, seed-eating bird, plants, and dog. The organism which will have the maximum concentration of harmful pesticides coming through the food chain is most likely to be :
(a) cat
(b) plants
(c) dog
(d) seed-eating bird
In addition to wheat plants, a crop field ecosystem has organisms such as snake, peacock, eagle and mice. If the wheat plants are sprayed with pesticides periodically, which of the following will have the minimum concentration of pesticides in the body?
(a) snake
(b) eagle
(c) mice
(d) peacock
Observe the food web and answer the questions given below:
Why do all food chains start with plants?
In the given food chain, suppose the amount of energy at the fourth trophic level is 5 kJ, what will be the energy available at the producer level?
Grass → Grasshopper → Frog → Snake → Hawk
