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: D
Explanation:One of the reasons for this is that there is little or no magma available at the plate boundary. The most common magmas at constructive plate margins are the iron/magnesium-rich magmas that produce basalts.
Well Rocks at high elevation are exposed to low temperature and high winds they weather quickly and rock at sea level can be weathered by the ocean waves.
Answer:
I think the answer is D ... but I am having a second thought I think it is B
Answer
A thick grouping of nerves that run down the back of the embryo
Explanation
The dorsal nerve cord is special embryonic characteristic of the ganglia. It is a hollow dorsal cord that is composed of a section of the exfoliated coagulant that forms a hollow tube unlike solid abdominal tubes in other animal species. It is located in the vertebrae of vertebrates.
