Question

Give reason

(a)Valves are present in veins

(b)Arteries have thick elastic walls.​

Answer 1

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ʀᴇǫᴜɪʀᴇᴅ ᴀɴsᴡᴇʀ-:

A)

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Unlike arteries, veins contain valves that ensure blood flows in only one direction. But, Arteries don't require valves because pressure from the heart is so strong that blood is only able to flow in one direction. Valves also help blood travel back to the heart against the force of gravity.

B)

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Arteries carry oxygenated blood from the heart to the different body parts. Blood emerges from the heart under high pressure. In order to withstand this pressure, arteries have thick and elastic walls.

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Answer 2

Answer:

a) Valves are present in veins to stop the backward flow of blood.As veins carry blood from other parts of the body and bring it back to heart there are possibilities of blood flowing back. So valves are present..

b) As heart pumps blood at a high pressure, to withstand the pressure thick elastic walls are present for arteries..

Explanation:

Hope this helps you my friend