Plants are able to respond to the environment in multiple ways. Shoots grow upwards, towards light, in a process called phototropism. Roots, on the other hand, grow downwards into the earth towards moisture - this is called hydrotropism. Plants also respond to the direction of the force of gravity - this is called geotropism. Roots grow towards the force of gravity, down into the ground, while shoots grow upwards and away from the force of gravity.