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Regarding the first question:
31. The vessel that has a more muscular middle layer and is more elastic than the others is the Artery. Arteries have thick muscular walls to withstand high pressure and elastic fibers that allow them to stretch and recoil as blood is pumped through.
Moving on to the second question:
32. The purpose of the valves in the heart is to prevent backflow of blood. Valves in the heart ensure that blood flows in one direction by closing to prevent the backward flow of blood during each heartbeat, thus helping maintain the efficiency of blood circulation.
I hope this helps clarify the concepts for you. Let me know if you have any more questions!
