How do Demetri's results show that digestive enzymes are crucial to maintaining homeostasis inside the body?

According to the diagram, what sources contribute to the phosphorus found in soil? according to the diagram, phosphorus found in soil contributes phosphorus to what other sources? (site 1)

Apopulation of black bears depends on salmon from a stream for food. if a drought causes the stream to run dry one year, how will this likely impact the black bear population?

Why do we perceive objects as retaining their brightness under different lighting levels?