• Ahmed Khan developed polyblend which is a fine powder of recycled modified plastic.
• He mixed this polyblend with bitumen and used to lay roads.
• This enhanced the water repellant property of bitumen and increased the road life.
• Khan offered a price to rag pickers which enhanced their income and improved their livelihood.
• Thus solid waste management was achieved by removal and proper disposal of plastic waste from the city.
a) Ecological pyramids represent the relationship between different trophic levels in terms of number, biomass or energy.
Limitations of ecological pyramid:
1. It does not take into account the same species belonging to two or more trophic levels.
2. It assumes a single food chain which almost never exists in nature.
3. It does not accommodate a food web.
4. Saprophytes are not given any place even though they play vital role in the ecosystem.
b) Inverted food pyramid means that consumers are more than producers. The pyramid of biomass in aquatic ecosystem like sea is generally inverted.
PP: Primary producer (Phytoplankton)
PC: Primary consumer (Zooplankton)
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