Plants do not have any nervous system but yet, if we touch a sensitive plant, some observable changes take place in its leaves. Explain how could this plant respond to the external stimuli and how it is communicated.
Answers
mark brainliest plzzzz....
The leaf folding response by Mimosa sp. is a very well studied example of electric signaling by mechanosensitive ion channels in plants. This is not memory as we define it, but more of a chemical desensitization. Ion channels will "adapt" or desensitize when activated repeatedly. Why? This is a protective response to prevent overstimulation and cell damage. Also known as habituation, this desensitization can happen on a short time scale or may be long lasting. One established way in which this "memory" can be long lasting is by epigenetic modification of DNA. The plants that needed to keep their leaves open to light may have had another chemical signal override the down regulation. It's all very interesting biochemical signaling of course, but not at all the same as "consciousness" or "memory" mediated by nervous system in higher animals.
Shaking and mechanical pressures are detected by mechanosensitive ion channels (TRP channels are an example). They are well known in both plants and animals. When activated to open, they move ions across membranes to change the electric potential. This in turns leads to chemical signaling. Mechanosensitive channels will desensitize to protect the cell from excessive activation since too much calcium influx can cause cell death. It's all chemical in the end :)
the movement of plants by touching or external stimuli is because of turgor pressure changes and water movement.for example, closing of pitcher in pitcher plant is due to rapid turgor pressure changes.