{Nutrient and water delivery, described and explained}
As parents, it's important to remember that good things don't happen all the time!
Our little guy needs to be continually supported. But often times, things can happen that may not be preferable, especially in our eyes. However, some of these occurrences are necessary in our baby's life. We'll just have to get used to it!
One such occurrence is transpiration. Transpiration is the loss of water from our baby boy via evaporation the aerial parts of his little plant body. Transpiration will occur when his stomata are open, and when the air around his leaves is drier than the air inside his leaves. During the day is usually when his stomata are open. And whenever atmospheric humidity is less than 100%, air around the leaves will be drier. Thankfully, our little man will replace the water lost via transpiration with water he absorbs from his roots (that his loving parents provided!).
This uptake of water, however, would not be possible if we did not understand water potential. Water potential is the potential energy that water has in a particular environment. This energy is compared to the potential energy of pure water at room temperature and atmospheric pressure. Differences in water potential ultimately determines the direction of water movement. Water will always flow from and area of high water potential to an area of low water potential. Solute potential and osmotic potential are all factors that affect water potential, among other things like pressure, temperature, and the environment in general.
Pressure plays a very important role. If our little baby was an animal (he really can be sometimes!), his cells would burst if we placed him in a hypotonic solution where water was entering his cells continually via osmosis. Thankfully, this does not happen to our little munchkin, because he is a plant! Silly!
Our little guys cells often swell in response to incoming water. But instead of swelling to the point of bursting, the plasma membranes push against the cell wall, which is rather rigid. Because of this rigidity, the cell wall resists expanding of the volume by pushing back. Thus, as water moves into the cell, the turgor pressure, or pressure inside the cell, increases until the force, or pressure, from the wall is induced. Turgor pressure is extremely important in pressure potential, and overall potential of the cells as well. Proper turgidity leads to healthy looking cells, which leads to a healthy looking baby boy!
But in order for our sweetie pie to utilize the water it takes in, and further transport necessary nutrients to make sure it is healthy and thriving, vascular tissue is necessary. The vascular tissue system is a supportive, long-distance transporter of water and dissolved nutrients. Ground tissue makes and stores the products, and vascular tissue moves them to wherever our little guy needs!
But these vascular tissue are complex, and made up of two complex tissues: xylem, and phloem. (Poppa Jack should be talking about phloem in food delivery later, so we'll stick with xylem).
Xylem conducts water and dissolved ions in ONE direction: from roots to shoots (xylem can be so stubborn!). Xylem consists of many important cell types, two of which are tracheids and vessel elements. The tracheids are the water-conducting cells, and the vessel elements are other conducting cells present in angiosperms. Both tracheids and vessel elements have thick, lignin-containing secondary walls that often are set in spiral-like patterns. When we heard both are dead upon maturity, let's just say we almost died! But we soon realized this is perfectly natural, for it results in their filling with fluid that they conduct. Tracheids are long, slender, tapered-ended cells. Tracheids have pits, or gaps in the secondary cell wall where only the primary cell wall is present. Vessel elements are shorter and wider, and have perforations in addition to pits, which are openings that lack both primary and secondary cell walls.
No comments:
Post a Comment