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By Mona

India In

If the temperature increase osmotic pressure increases.
HOW? If I increase the temperature it should then greatly affect the plant.



Dredging my memory from too many years ago, Mona, osmosis is the transfer of solvents across a semi-permeable membrane. As pressure on one side of the mebrane increases then the rate of solvent transfer across the membrane decreases; therefore, less solvents eg nutrients would pass across the membrane in the plant. In the case of plants the 'membrane' is the wall of the plant cells and I would assume that, even if you increase the room temperature, the temperatures both inside and outside the cell would be more or less equall. Hence no temperature gradient and no change in the rate of transfer of nutrients.
Hope that the above is correct. Anyone else with more up to date knowledge please join in.

16 Jan, 2013


osmosis is the movement of water across the cell membrane. the substances dissolved inside affect how much water there is to move. large molecules arent able to move through the membranes but may move through the cell wall. The cell wall is pretty much freely permeable to most solutes.

The osmotic pressure is a combination of pressure from the contents of the cell, being resisted by the membarne pushing back.

Pressure is due to the particles colliding with the membrane. the higher the temperature the more energy the particles have and the more collisions there are. More collisions means morre pressure.

However raising the temperature will also affect how efficiently enzymes work in the cells. Too high and the enzymes get destroyed and the cell chemical activities stop. So although you want water to be freely available for photosynthesis, if the enzymes that 'run' are destroyed the plant will die.

16 Jan, 2013


Does that mean then that each individual plant has a set potential temperature when denaturisation takes place and is the dependant on the size of the leaves on the plant? Hypothetically?

In fact if you think about Cacti they have needles to waterloss is reduced and the reverse could be said about rainforest plants with their large waxy leaves.

Perhaps this pressure also dictates why the plants move as if they are following the sun?

16 Jan, 2013


certainly some plant species are better adapted to the environment in which they are now found. Generally 40 degrees C tends to be the upper limit when growth is significantly lowered. plants then have a time delay where they are able to resynthesise any denatured [damaged] enzymes.

Heliotaxis and the way venus fly traps close is certainly down to changes in water pressure .

Cacti also photosynthesise slightly differently to other plants and use a different set of chemical pathways. and they are able to move their chloroplasts where photosynthsis takes place around the cells. They also have these cells lower/deeper in the flesh of the plant so further away from the effects heat.

all clever stuff that makes my brain ache :o)

16 Jan, 2013


Wow Seaburn, is there such a thing as Brainlysis! Lol

16 Jan, 2013


yes ! [ look away now if you dont want brain ache] when you drink too much water, water enters the brain cells by osmosis . they start to swell like a ballon and because there isnt a cell wall the cells can then burst. just like an overfilled balloon. the resulting brain damage can be fatal.

well you did ask :o))

16 Jan, 2013


OMG! Hydrogen bonds 1 - Human epithelium 0.

16 Jan, 2013


Just sometimes you could wish that you had not asked ;-))))

16 Jan, 2013


Or that you had not read... lol

16 Jan, 2013


Actually, there is little relationship between the size of leaves and the the temperature tolerances of plants. Creosote Bush (Larrea tridentata)--leaves less than 5 mm wide--and the true Castor Bean (Ricinus communis)--leaves more than 30 cm wide--both operate most efficiently at around 35ยบ C.

16 Jan, 2013


i did say look away now .

I totally agree Bulba/Bamboo :o)))

Yes thats true Tugbrethil. The Creosote's small leaves help reduce water loss due to where it lives. The Castor Bean doesnt have a shortage of water problem so doesnt need smaller leaves.

16 Jan, 2013


Seaburn, your brain or anyone's for that matter has no pain receptors so your 'brain' can't actually 'ache'! :) ;)

And do you mean to say that pressure increasing inside the cell due to vibration will actually cause solvent(water) to move in? If pressure is already high inside how will anything move in?

18 Jan, 2013


yes mona i know the brain cant feel pain, it's just an expression. :o) when I ask my daughter how she's getting on with her maths homework she often says 'i'm getting brain ache'.

water moves by water potential differences. due to differences in concentrations of solutes in cells. increase in temp speeds up molecular movement and therefore the rate of osmosis. physical pressure is measurable and is the physical resistance of the wall to increasing volume in the cell. animal cells swell and then rupture, where as plant cells normally dont.

is your query to do with an exam question if so to what level? Then I might be able to refer you to the appropriate texts.

18 Jan, 2013


Oh gosh, read through twice, understand some but not all of it, never too old to learn though, fascinating.......

18 Jan, 2013


i'm pleased that it makes sense Lincslass. it certainly is fascinating and I still struggle with the pure biochemistry. never liked it so reluctant to learn it.

18 Jan, 2013

How do I say thanks?

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