Biology terminology help - Osmosis

[Squarehed]

Late night biology coursework-writing session.

Just writing my conclusion and wondering, is it scientifically correct to say something to the effect of:

'water osmoses across a semi-permeable membrane from an area of high water potential to an area of lower water potential'

or is it something like

'water molecules diffuse across ...[same as above]'

Is it right to use 'diffuse' in there, as I vaguely remember my biology teacher saying diffusion shouldn't be used when talking about osmosis. I think it's the second but the first is just easier to write.

 

[Phog]

moves by osmosis

 

[Butters]

moves by osmosis

^^^^

 

[Squarehed]

Thanks

BUT, new question, what happens when trying to define osmosis? I can't use the word in its definition? Would that be right to use 'water molecules diffuse across a semi-permeable membrane from a hypotonic solution into a hypertonic solution'?

 

[loopstah]

Osmosis is a special type of diffusion, so you could use the word diffuse.

 

[oddjob62]

You could just say "the movement of water molecules across....."

 

[Sinque]

The movement of water from a high to a low concentration, basically it

 

[Phog]

Thanks

BUT, new question, what happens when trying to define osmosis? I can't use the word in its definition? Would that be right to use 'water molecules diffuse across a semi-permeable membrane from a hypotonic solution into a hypertonic solution'?

I tend to use words such as migrate, especially as the diffusion/osmosis pitfall is one they like to pick up on at school.

 

[Squarehed]

Cheeeeers, my worry is just my teacher was saying she's going to be really anal and particular about the terms we use when she marks it, so I want to make up for the difficult exam I felt I earlier this term

 

[Tefal]

osmosis is the process by which water molecules move across a semi-permeable membrane from an area of high water potential to low water potential.

 

[Jon33]

^^^ sums it up

 

[loopstah]

osmosis is the process by which water molecules diffuse across a semi-permeable membrane from an area of high water potential to low water potential.

 

[Phog]

I disagree with the use of the word diffusion there. It indicates a random movement of the molecules however in reality, they are being drawn across the membrane.

 

[Tefal]

wouldn't put diffuses if she's being anal about terms, as it's a different thing.

 

[loopstah]

I disagree with the use of the word diffusion there. It indicates a random movement of the molecules however in reality, they are being drawn across the membrane.

How are they being drawn across the membrane? The only difference between regular diffusion and osmosis is the involvement of a partially permeable membrane.

Osmosis is a special type of diffusion.

 

[Jon33]

Make sure you put "net" movement of water molecules in there aswell.

 

[Tefal]

How are they being drawn across the membrane? The only difference between regular diffusion and osmosis is the involvement of a partially permeable membrane.

Osmosis is a special type of diffusion.

all my old text books always refer to it as move/movement etc to avoid confusion.

 

[Kol]

Well, I've just looked in the glossary of Biology (7th Edition) by Campbell & Reece and they simply define it as, "(oz-mo-sis) The diffusion of water across a selectively permeable membrance."

I would happily go with that, especially as plenty of Profs/docs who lecture my degree use the term diffuse.

Silverthorns Human Physiology (3rd Edition) glossary has it simply as, "The movement of water down its concetration gradient across a membrane." A little simplistic in my opinion.

Prescott, Harley & Kliens Microbiology doesn't particularly have an exact definition, merely stating that during osmosis, water moves across a selectively permable membrane (such as the plasma membrane) from dilute solutions (high water concentrations) to more concentrated solutions (low water concentration).

Apart from a few medical microbiology textbooks (which don't appear to have many useful definitions) and all my neuroscience text books (such as Purves et.al.) those are the only other books I have from degree level which have a simple definition of osmosis in them. Hope they help

 

[lord filbuster]

isn't diffusion entirely random? Each molecule of water has an equal chance of crossing the membrane, and because there are more water molecules on one side, on average more molecules cross. But water molecules on the other side can still move up the concentration gradient, but since there are less of them there will be on average less molecules crossing the membrane, the net effect is water molecules move down the concentration gradient until there are about equal numbers on each side.