University years

How do plants absorb and transport water?

Just before finishing high school I realised that what I was most curious about was figuring out how our brain works and how it is possible that chemical and electric signals can be converted in such complex behaviours as it could be having memories or feelings and in general everything we do in our everyday lives, from talking to dreaming, from having a goal in life to depression an so on. As I mentioned in one of my previous post my family decided to let me choose my bachelor, trying not to influence my choice in both the main subject and the university location. Therefore, I started researching on internet where I could possibly achieve my goal of studying the biology of the brain and what I realised was that to study the brain I had to obtain a general Biology bachelor degree, since all the Neurobiology courses offered in Italy were master courses.

I had a quick peek at the Biology courses around and the idea to have lectures on insects or plants was not appealing at all and not fitting to my future brain related studies. So the only chance I had to get a bachelor before starting studying the complexities of the brain was to combine my love for biology with my love for chemistry and I chose to start a Biotechnology course in a small town close to Milan called Pavia. I have to admit it: the first year of my university studies was very tough, not so much in terms of studying hours or lectures, but moving from a city in the South of Italy to one in the North was quite a cultural shock for me and also adjusting to live by myself after a life spent home pampered by my parents with new friends and rhythms challenged me a lot. But I will go more into deep about it in my future posts.

However, since I mentioned how you have to get into plants’ biology in many Biology bachelors and since I also had a course on plant cell biology, today for the SRF I will talk about the mechanism that plants use to absorb and transport water.

“Science Related Fact” (SRF):

As you all might know and guess, water is pretty important for plants: nutrients are dissolved in water, that is used as a carrier to transport them from the soil to green plant tissues, and also it is used during the photosynthesis process, where the end product is also conveyed through water to various plant parts. Plants can absorb water through their entire surface – roots, stems and leaves – but, the majority of it it is absorbed from the soil by roots, that are in close contact with the thin film of water surrounding the soil particles (see picture below).

Water movement throughout the plant, from its absorption in the roots to its transpiration in the leaves. From agritech.tnau.ac.in

Unlike animals, plants lack a pump like the heart to move fluid in their vascular system. The water absorbed and transported through plants is moved by negative pressure generated by the evaporation of water from the leaves. However, the water movement is also passively driven by chemical potential gradients.

This system is able to function because water is “cohesive” — it sticks to itself through forces generated by the hydrogens in the water molecules. These forces generated by the hydrogen bonds present in the water molecules help explain how water can be transported in some trees up to 100 m or more above the soil surface (see picture below).

The “Sequoia sempervirens” is the tallest tree in the word, with a maximum height of more than 115m. From wikipedia.com

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