Geotropism is the influence of gravity on plant growth or movement. Simply put, this means that roots grow down and stems grow up. ... In this case, the stimulus is gravity. Upward growth of plant parts, against gravity, is called negative geotropism, and downward growth of roots is called positive geotropism.
The spinal cord is associated with 31 pairs of spinal nerves. Spinal nerves are considered mixed nerves because they contain both motor and sensory axons.
