Explanation:
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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.
Biotic factors are all of the “alive” factors in the environment which includes all living organisms. Abiotic factors are opposite, are “non alive” factors which may include water,soil,air,rocks,and etc.
In a hypotonic solution
Explanation:
Contractile vacuoles are used mainly by protozoans like an amoeba in osmoregulation. When the organism environment becomes hypotonic to the cell's cytoplasm, the contractile vacuole pumps more rapidly. This is because, in the hypotonic environment, more water is getting into the cell by osmosis. To maintain the right osmotic pressure in the cell more water is needed to be pumped out – this is a function of the organelle.
A. an open circulatory system
Explanation: In an open circulatory system, the blood is not enclosed in the blood vessels, but is pumped into a cavity called a hemocoel
