Photosynthesis

[gene]

Ya Certainly better.

I still have a question.

Isn't the pressure by the sugar solution area more than the pure water?

It has a higher density

 

is it osmotic pressure you are talking about?

[chadn]

I still have a question.

Isn't the pressure by the sugar solution area more than the pure water?

It has a higher density

 

Osmosis isnt that important in the movement of CO2. Think about it. Osmosis is the diffusion of water across a semi-permeable membrane, but we are not concerned about water here, we are concerned about how CO2 is diffused into the cell, not how water moves. That is, as long as we're still talking about Carbon assimilation.

 

And another thing:

 

The oxygen was never gaseous in the first place though.

 

Not true. Ribulose Biphophate (RuBP), the molecule that reacts with CO2, also reacts with O2. Since O2 enters the stomata with CO2 it is also reacts with RuBP and gets assimilated into the plant cell. I think the ratio is somewhere around 1-3 for O2-CO2.

[premjan]

What would a macroscopic piece of semi-permeable membrane look like? Is it even posisble to manufacture this? Is that what a "sponge" is?

[chadn]

What would a macroscopic piece of semi-permeable membrane look like?

 

Semi-permeable means that there are openings small enough for the water molecules to cross, but not larger substances like carbohydrates. A blown up version wouldnt be semipermeable because other substances go pass through.

 

Is it even posisble to manufacture this?

 

There are semi-permeable materials out there, cant think of any off the top of my head. We used some sort of material in a Biol lab once to demonstrate the concept but its been to long to remember what it was.

 

Is that what a "sponge" is?

 

No, a sponge has pores that allow water to be retained, but its not a semi-permeable material.

[gene]

There are semi-permeable materials out there' date=' cant think of any off the top of my head. [/quote']

 

Visking Tubing? What about cellophane tape?

[chadn]

Visking Tubing? What about cellophane tape?

 

Actually I think it was visking tubing that we used.

 

Isnt cellophane tape impermeable to air?

[premjan]

http://web.ukonline.co.uk/webwise/spinneret/life/osmsis.htm

apparently yes to visking tubing.

[gene]

not sure of cellophane tape. can't really remember. i did such an experiment with cellophane tape. Maybe i remembered wrongly.

 

Ya, the web, shows the potato, animal cell membrane too.

[premjan]

what substances would a potato membrane admit? Only water?

[Primarygun]

what substances would a potato membrane admit? Only water?

Usually small molecules, like glucose

[gene]

Usually small molecules, like glucose

 

Oh. i don't think so. Would you also consider sucrose?

 

Or maybe is that the reason why glucose solutions are not used. instead, sucrose?

[Primarygun]

Cell membranes are usually selectively permeable and allow small molecules passing through it by means. Glucose can passes through it.

[gene]

do have any idea, what selective membrane is used in a dialysis? Or could it be just the visking tubing?