It's basically a wave that moves back and forth at regular speed through matter. because of that it transfers energy through a medium (matter). however the movement of the wave is limited because of this but it can still move over long distances. so because of this these types of waves don't move far from their original point or Equilibrium position. in short think of throwing a pebble into water and seeing the little ripples from it, that's a mechanical wave.
In turtles, the heart has two atria and a single ventricle partially divided by a wall of tissue called a septum
In crocodiles, there are two atria and two separate ventricle
Answer to question four is B
