This is probably an easy question for you guys, but I have no idea.
We're doing a plant lab at school involving Lima beans. For one of the beans, we added table sugar to the water. Its growth has been shunted but it's still alive.
I was reading up on the effects of sugar water and I learned that plants aren't able to absorb enough water if sugar is present. I was wondering, are plants able to absorb the sugar molecules as well? The compound in question would be sucrose, as table sugar is comprised of sucrose.
And if plants are able to absorb the sucrose, what happens to it? Are they able to utilize it in any way???
Any help is appreciated. If you can lead me to other websites, I'd appreciate that too.
That site is basically listing the points I need for my lab one after another.
Thanks a lot.
Also have a quick question if you're willing to answer it. Some plants produce sucrose, such as the sugar cane and sugar beet. Since that can't pass through the semi-permeable membranes, there is never any sugar content in the soil?
Your question is a bit odd. Plants use sucrose as a transport molecule via the phloem. It is used as it is more stable and mre efficient to use than glucose. Eventually the plant will break it down and use its constituents in respiriation. Plants don't let any molecules diffuse from their roots; they use active transport to move minerals in. The sugars are made by photosynthesis in the leaves, they dont have much to do with the roots.
Hmmmm... I am not sure if I buy the osmosis bitt. Albeit I am going way against common belief. Plants absorb nutrients in only one way... in a solution. Hence the nutrients in the soil (whether they be organic or mineral based) are dissolved into the water and absorbed WITH the water.. If osmosis were how plants get water, they would not get the nutrients in that fashion. If osmosis were the real way plants get water, as suggested by adding sucrose to the solution, the minute the water hit the soil and dissolved nutrients, it would not be able to be absorbed. I believe more in capilary action. But that is just beginnning to take form...
As far as adding sugar water to your soil and seeing a decrese in the growth of the plant, I believe more is involved. What type of soil are the plants in? Is there a significant amount of organic matter in the soil? The sugar can be a form of food energy to microbes (bacteria and fungi) in the soil.. the microbes usually get their sugar from the plant. With the abundance of food, the microbes multipoly exceedingly.. Some microbes need the same nutrients that the plant does and therefore will rob the plant of the food it needs until they die and realease the nutrients as biomass.
As for your original question I would say yes. If the plant can transport a sugar solution, why couldn't it absorb it? Also, nutrients are absorbed as solutions.. water and suger is a solution.
If the plant was wilting I would say the osmosis theory is the culprit... was it? I would bet that microbes were the case robbing it of notrogen and stunting its growth. I bet it had no wilting? Hence no problem of water absorbtion?
JDUtah, I suspect you really have no clue about how plants actually absorb substances from the soil.
Water enters plant cells by moving from higher water potential to lower water potential. Water potential is composed both of solute potential(osmotic potential) and pressure potential, which in root cells is negative because of the suction force that originates due to evaporation in leaves. Capillary action contributes to the ascension of water in the xylem, but it does not help the water get there.
Now, on the absorption of solutes: ions are taken up through SPECIFIC transport. Each ion has a special transport protein for its uptake in the endodermis. Cations are usually taken up through uniporters, after being displaced from the binding to soil particles by H+ ions contributed by plant cells. Anions are usually taken up through symporters with H+. Not all particles in solution can be taken up by root cells: a specific transporter is needed for each substance. Root cells generally do not express the glucose/H+ symporter, because there is no need for it: there generally is no sucrose in the soil.
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter
1. Sucrose can and is absorbed via roots. However, its transport is liked to K+ ion.
2. External sucrose intake (in large amounts) could impede photosynthesis (no need to produce sugar) and produce paler plants.
3. Sucrose by itself will not seriously impact plant growth, however, absence of other nutrients (N, P, etc.) will.
Sorry, I have reading and reading this forum for days ... I finde this question on page 3 or 4
This is one of questions on which I wish to hear an answer.
For now there is two posts,MrMistery and Cat, but unfortunatelly Im very tiny with Bio knowledge and can not make right conclusion.
Is here some more opinion or better some link more then this http://www.purchon.com/biology/osmosis.htm
let me verify answer from one more valide link, or this question are finished like yes & no with truth somewhere els ...
this is really great forum !
It's funny that this thread is on here.
I just finished up a project involving sucrose concentration and Pisum sativum seeds.
We used concentrations of 1.0M, 0.50M, 0.25M and a control and the sugar doesn't seem to prevent germination so much as slow the process down.
I'm assuming since you said lima beans you do mean the actual beans and not the plants. This would definitely make it an issue of osmosis and not one of whether or not they can actually use the sugar. The problem would be whether it was possible for the seed to imbibe enough water to start the germination process. We still need to do another experiment and finish compiling our data for the current one but it seems as though the seeds simply adapt to the hypertonicity and the higher the concentration, the longer they take to germinate..
Provided your seeds don't just start molding after three days that is
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