‘Hydrotropism’ is the directional growth response of plants towards or away from water, and ‘chemotropism’ is the response to chemicals. An example of chemotropism is the growth of pollen tubes towards ovules.

Plant cells change shape by altering water content, leading to swelling or shrinking. This process, unlike animal muscle cells, results in the required changes in shape for movement.

In the sensitive plant, movement occurs at a point different from the point of touch. The communication of touch-related information utilizes electrical-chemical means among cells.

The sensitive plant detects touch through electrical-chemical means, communicating information from cell to cell. Plant cells change shape by adjusting water content, leading to swelling or shrinking and, consequently, leaf movement.

The directional movement of a seedling, such as the root going down and the stem coming up, is a result of growth. If growth is prevented, the seedling will not display the expected movement.