*A tropism is a plant produced by the action of hormones, compared to an external stimulus. The plants have no sense organs. Nor can move to change the environment that surrounds them, is growing too slowly in a certain direction they may be: Positive when the plant grows toward the stimulus Negative when the direction is opposite
*Nastia is a certain areas of a plant compared to an external stimulus and diffuse, based on processes of growth or change in the turgidity of groups of cells that vary in volume by controlling the entry and exit of water movement result is not influenced by the direction of the stimulus.
*The reaction electrotropismo orientation of some animals in relation to an electric field.
*The hidrotropismo corresponds to a movement to plant wetlands, where the water. Given this root stimulation a clear positive response.
*The incentive is that geotropismo on the gravitational force of the bodies. Ie, the stems always grow up to find the necessary light for photosynthesis, the roots into the soil, there you will find water and minerals.
*Phototropic reaction is the ability or by hormones, a plant to change the direction of its normal growth occurs when the light changes, as in growth, the light is very important and also in carrying out photosynthesis, rioja which leads us to conclude that in response to this stimulus, the plant grows toward the light source