Valves ensure blood flows toward your heart. Vein valves work to bring the blood that flowed down via arteries back up to your heart.
Adenine, guanine, & cytosine | uracil & thymine
Before cell reproduction or mitosis can proceed, the correct sequence of steps that must first occur is the following one: growth, chromosome replication, repair of chromosomal errors, and duplication of cell organelles. This is the right order in which these steps should happen before the cell is to reproduce or split itself into several parts during mitosis.
I guess it would be the sun?
C. the fallen trees become food for organisms
