Plants

[Lisa4NH]

when a plant takes in water it needs enery, where does it get this from?

[shammydodger]

From the local Cooper?

[shammydodger]

Sensible answer now, though not necessarily correct!

The manufacture of adenosine triphosphate (ATP) occurs in the mitochondria in plant cells. ATP is the source of the energy you refer to.

The take up of water is mainly through the root hair cells by osmosis. Osmosis, in itself, requires no energy as it occurs across a water potential gradient. However, this water potential gradient is in part set up by the active transport of ions into the plant. Active transport does require energy and, as these processes are linked, it can indeed be said that energy is expended in the uptake of water.

Mind, all this is from memory from A' Level biology, many years ago!

[shaun_04]

All plant energy initially comes from sunlight.

[shammydodger]

Shaun

Of course, as does all the energy on Earth.

[applebee]

photosynthesis....the sun!

[Sphinx_Svens]

You talking abot Enery The Eighth?

[Sphinx_Svens]

abot????... how do I feel now ... lol

[newtron]

shammydogger is correct. osmosis does play a role, but plants get most of their water for free by capillary action. Stick a capillary tube in water and the water will move upwards due to interfacial tension. The smaller the tube the higher the water will rise.

[shammydodger]

Newtron. Capillary action only works on water that is already in the plant. To get the water into the plant in the first place (across cell walls), osmosis is required.

[Lisa4NH]

Ah, thankyou all so much :D

[newtron]

shammydodger, roots are just capillary tubes. Water does not have to cross a cell wall to enter the roots.

[shammydodger]

Yes it does

[shammydodger]

Newtron

And if you don't agree, then we are going to have to disagree. If you don't believe that root cell hairs don't have cell walls.....

[shammydodger]

Should have said root hair cells, not root cell hairs!