Answer:
A biogeochemical cycle is one of several natural cycles, in which conserved matter moves through the biotic and abiotic parts of an ecosystem. ... Each of these elements is circulated through the biotic components, which are the living parts of an ecosystem, and the abiotic components, which are the non-living parts.
The two main types are DNA and RNA
Answer: D. Extinctions occur at higher rates during times of ecological stress when populations and species are poorly adapted.