What are the two most important processes in the cycling of oxygen in and out of the atmosphere

Why do leaves change color in the fall? green pigments break down and no longer mask the color of chlorophyll. chlorophyll breaks down and no longer masks the colors of other pigments. red- and yellow-colored pigments grow and mask green-colored chlorophyll. green-colored chlorophyll breaks down and turns red and yellow.

What molecules does hemoglobin decay into over time

How are viruses different from eukaryotic cells?