question_answer 55)

    Choose the correct statement that describes arteries, (a) They have thick elastic walls, blood flows under high pressure; collect blood from different organs and bring it back to the heart (b) They have thin walls with valves inside, blood flows under low pressure and carry blood away from the heart to various organs of the body (c) They have thick elastic walls, blood flows under low pressure carry blood from the heart to various organs of the body (d) They have thick elastic wall's without valves inside, blood flows under high pressure and carry blood away from the heart to different parts of the body.

Answer:

                  (d)Arteries are the vessels which carry blood away from the heart to various organs of the body. Since the blood emerges from the heart under high pressure, the arteries have thick, elastic walls. Veins collect the blood from different organs and bring it back to the heart. They do not need thick walls because the blood is no longer under pressure, instead they have valves that ensure that the blood flows in only one direction.