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Our Environment — Science STD 10 — Question

Maharashtra BoardEnglish MediumSTD 10ScienceOur Environment5 Marks
Question
What is ten per cent law? Explain with an example.
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Answer

Ten PerCent Law – According to ten 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.Example – Suppose 1000 Joules of light energy emitted by the sun falls on the plants. Consider a food chain:$\text{Plants}\ \ \ \rightarrow\ \ \ \text{Deer}\ \ \ \rightarrow\ \ \ \text{Lion}\\{^\text{(Producer)}}\ \ \ \ \ \ \ {^\text{(Harbivore)}}\ \ \ \ \ \ {^\text{(Carnivore)}}$
The plants or first trophic level has 10 joules of energy in it. Now according to 10 percent law, only 10% of 10 joules of energy (which is 1 joule) will be available for transfer to the next trophic level, so that the herbivore will have only 1 joule of energy stored as food at the second trophic level. 10% of the remaining 1 joule will be transferred to third trophic level of carnivore. So, the energy available in the lion as food will be only 0.1 joule.

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