Consider the roles of valves and blood vessel walls in moving blood through the body. if you were given a piece of flexible tubing and a small piece of plastic, how might you design a simple model that would simulate those roles?

The tube is like a blood vessel, and the plastic is just like the valves. The plastic piece in the tube opens when the water flows in the correct direction and close when water backflows. I hope that this is the answer that you were looking for and it has helped you.

One reason is animal teeth are in an extraordinary structure.another reason is animal teeth are creative

Is there a photo attached? it may not be loading correctly for me bc of my internet