Why is a polar bear referred to as a tertiary consumer?

Explain the importance of producers, primary consumers, secondary consumers. and decomposers in an ecosystem

How does natural selection change thephenotypes within a population over time?

Some mining processes involve removal of large areas of earths surface in the mined region this practice causes severe environmental damage by allowing which natural process to accelerate in the affected areas? a.precipitation b.erosion c.migration d.condensation