What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?
The movement in a sensitive plant and the movement in our legs differ significantly in their mechanisms and the structures involved.
In a sensitive plant (like the chhui-mui or touch-me-not), movement occurs without any nervous system or muscle tissue. When the leaves are touched, the plant uses electrical-chemical means to convey information from cell to cell. However, unlike animals, plants do not have specialised tissue for the conduction of information. The movement happens at a point different from the point of touch.
For movement to occur in plants, cells change shape by changing the amount of water in them. This results in swelling or shrinking of cells, which causes the leaves to fold up and droop. This movement is independent of growth and happens very quickly in response to touch.
On the other hand, animals have a nervous system for controlling and coordinating the activities of the body. Animals have specialised proteins in their muscle cells that enable movement. The information is conducted through specialised tissues designed for conduction.
The key difference lies in the mechanism: plants rely on water movement within cells to change shape, while animals use specialised proteins in muscle cells. Additionally, plants lack specialised tissues for information conduction, whereas animals possess such tissues for efficient communication.
Explanation
This question tests the student's understanding of control and coordination mechanisms in plants versus animals. The textbook clearly establishes that plants lack both nervous system and muscle tissue, yet can still respond to stimuli like touch. The sensitive plant uses electrical-chemical means to communicate information and changes cell shape through water movement (swelling/shrinking). In contrast, animal movement involves specialised proteins in muscle cells and a nervous system with specialised tissues for information conduction. The answer should highlight these fundamental structural and mechanistic differences.
Solution Steps
Step 1: Identify that plants lack nervous system and muscles while animals have both.
Step 2: Explain how plants use electrical-chemical means and water-based cell shape changes for movement.
Step 3: Describe how animals use specialised proteins in muscle cells and specialised tissues for conduction.
Step 4: Conclude with the key differences in mechanism and structure.