It is now a general opinion that if we see something moving, it is alive.
Some of the motions in living organisms are due to growth, as we see in plants. On the other hand some movements are not connected with growth. Running, walking, chewing etc are movements that are not connected with growth.
We associate visible movements with life because we think these movements occur as responses to environmental changes. These movements also occur when living organisms attempt to use environmental changes to their advantages.
A sunflower moves in the direction of light. Plants grow towards sunshine. Many times we move to protect ourselves from changes in the environment. We detect changes and respond to them with movement.
Movements of organisms in response to environment are controlled carefully. Any change in the environment evokes an appropriate movement in response.
The movement to be made depends on the event which triggers the movement. There is a system in the body which recognizes various types of events that occur in the environment. This system allows only a correct movement in response.
Thus, it is clear that living organisms have systems that control and coordinate their activities. For this, there are provisions of specialized tissues that control and coordinate activities.
What is control and coordination? Well, the activities of a body are needed to be maintained within a limit to avoid any risk. This is called as control. But every activity needs efforts of two or more organs for which mutual responses are necessary. This is what we call coordination.
control, coordination, living beings
