Who proposed 10 per cent law ?

Explanation

**Step-by-Step Solution:**

1. **Understanding the 10% Law**: The 10% law refers to the principle that when energy is transferred from one trophic level to the next in an ecosystem, only about 10% of the energy is passed on to the next level. The rest of the energy is lost, primarily as heat.

2. **Energy Transfer Example**: For instance, if the primary producers (like plants) have 1000 joules of energy, when this energy is transferred to the primary consumers (herbivores), only 10% of this energy, which is 100 joules, is available to them. This process continues as energy moves up the food chain:
- From primary consumers to secondary consumers, only 10% of 100 joules (which is 10 joules) is transferred.
- From secondary consumers to tertiary consumers, only 10% of 10 joules (which is 1 joule) is transferred.

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