Nearly all of the energy comes from the sun
Answer:
The return of blood to the heart is assisted by the action of the skeletal- muscle pump. As muscles move, they squeeze the veins running through them. Veins contain a series of one-way valves, and they are squeezed, blood is pushed through the valves, which then close to prevent backflow.
Answer:
A mass movement can either be slow or rapid. The slow downward movement of materials in a slope is called creep. This happens when the soil loosens up because of water and burrowing animals. In contrast to this, the rapid movement of large materials in a slope is called landslide.
Answer:
after meiosis, each new cell will be genetically different due to random exchanges of chromosomes.
