Blood cells are produced in the bone marrow and the bone marrow is part of the skeletal system. So the answer would be skeletal system<em>. </em>
In secondary succession, the pioneer species are plants that are adapted to exploit disturbances rather than bare rock. They typically include plants such as grasses, birch trees, and fireweed. Organic matter from the pioneer species improves the soil so other trees and plants can move into the area.
the gases that kept different planta is A
