Question

why are biogeochemical cycles important? earth is a closed system. that means the amount of rocks, metals, carbon, nitrogen, oxygen, and water on earth. so, it is essential that biogeochemical cycles these materials as they move through earths subsystems.

Explanation:

1. For the first blank: In a closed system, the amount of matter (like rocks, metals, carbon, nitrogen, oxygen, water) is constant, so it "stays the same" (or "remains constant").
2. For the second blank: Biogeochemical cycles are responsible for recycling or reusing these materials as they move through Earth's subsystems (like biosphere, geosphere, hydrosphere, atmosphere), so a suitable verb here is "recycle" (or "reuse", "circulate").

Answer:

First drop - down: stays the same (or remains constant)
Second drop - down: recycle (or reuse, circulate)