In a convergent plate motion, two tectonic plates move towards one another. Due to this type of plate motion, the denser plate subducts below the less dense plate, as a result of which a subduction zone forms and above this zone, there lies a trench. This trench is a depression that marks the boundary between the two plates. As the sinking plate melts underneath, the magma in association with the melt rises upwards, and thereby give rise to the formation of a volcano or a volcanic island. It also creates an island arc or a volcanic arc.
The cause of mutations in gene expressions are the changes of gene instructions that causes your protein to malfunction. The effect of mutations are the genes not being able to function properly and send the wrong codes/info to your cells.