Thursday, May 28, 2015

Osmosis in Plant Cells Revisited

I have to post this article again as I believe some here would argue that the amount (quantity) of rainfall a plant receives would somehow effect the regulatory turgor pressure P exerted by the cellulose walls of the plant.

Similar to how some may assert that the amount (quantity) of forex transactions can somehow effect the exchange rate of currencies.

I would say the amount (quantity) of rainfall cannot affect the plant's turgor pressure P, that regulatory pressure is fixed and defined in the genetic code of the plant species.

Here is the post again for background:

Below a diagram depicting the process of osmosis in a plant cell. Article here.

Some explanation here about how regulated plant systems respond to environmental variation or environmental imbalances... variations and imbalances in bold, as are the indicated responses in exchange rates across the cell wall membranes.

The significance of osmosis to plant function is best appreciated by describing its role in the regulation of guard cells. 
Guard cells are specialized cells scattered across the surface of plant leaves. Each pair of guard cells surround a special pore, termed a stoma (plural stomata), and control its opening. Guard cells have a special arrangement of microfibrils in their walls, so that when the guard cells swell the stomata open. When the stomata of a plant leaf are open, this increases photosynthetic gas exchange and movement of water out of the plant by transpiration. 
In many plants, certain environmental stimuli, such as sunlight, stimulate the guard cells to take up potassium from surrounding cells. This causes their osmotic potential (π) to decrease and water moves in by osmosis. Thus, the guard cells swell, the stomata open, and the rate of gas exchange through the stomata increases. This increases the rate of photosynthesis and plant growth. 
Other environmental cues, such as water shortage, cause plants to transmit chemical signals to the guard cells, causing them to release potassium, which increases their osmotic potential, and to lose water by osmosis. This causes the guard cells to shrink, so closing the stomata, and decreasing the rate of water transpiration through the stomata. This reduces water loss and prevents wilting of the plant. 
Plants rely upon other environmental signals to regulate the osmotic movement of water into their guard cells and the opening of the stomata, so that the advantage of increased photosynthesis is balanced against the disadvantage of increased water loss.

I would analogize the current state of the EUR/USD relationship as isotonic/flaccid from the diagram above; stabilized or in near equilibrium in/around the 1.07 area.

On second thought I'll change my mind the situation is slightly non-isotonic (hyper or hypo tonic depending on which side of the membrane is your pov I guess) the current situation is slightly "favorable" to the US and we should see some continuation of increasing real terms of trade in the US vs. the EZ under present "environmental" conditions... the "environment" can of course change at some point.

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