Lesson hub

Can't find the answer? Try online tutoring

How it Works

We have the UK’s best selection of online tutors, when and for how long you need them.

Getting 1-on-1 support is cheaper than you might think.

Participating users

Welcome to our free-to-use Q&A hub, where students post questions and get help from other students and tutors.

Follow the trail of responses and if you have anything to add please sign up or sign in.

You can ask your own question or look at similar Biology questions.

Hello dw999999,

For AQA and Edexcel GCSE and iGCSE: 

Water often moves across boundaries by osmosis. Osmosis is the diffusion of water from a dilute to a more concentrated solution through a partially permeable membrane that allows the passage of water molecules. 


This depends slightly on the level you are working at. For GCSE I would say:

"The movement of water from an area of high water concentration/low solute concentration to an area of low water concentration/high solute concentration through a semi-permeable membrane"

At A level I would say:

"The passive movement of water from an area of high water potential to an area of low water potential through a semi-permeable membrane."

"Diffusion of fluid through a semipermeable membrane from a solution with a low solute concentration to a solution with a higher solute concentration until there is an equal concentration of fluid on both sides of the membrane"


Osmosis is the movement of water molecules from higher concentration towards lower concentration.

The definition of Osmosis is:

The net movement of water from an area of higher water potential to an area of lower water potential, across a partially permeable membrane.

Regards, Kenndel. 

Osmosis - the net movement of water molecules through a partially permeable membrane, from an area of high water potential (the higher concentration of water molecules) to an area of low water potential (a lower concentration of water molecules).  Water molecules diffuse down this water molecule concentration gradient until there is a  balance of water molecule concentration either side of the membrane. 

Osmosis is the movement of water through a semi-permeable membrane from a region of high water potential (less concentrated) to a region of low water potential (more concentrated).

The definition of osmosis is the movement of water from a area of high water potential to an area of low water potential.

For A level a definition such as this will be great....

Osmosis is the net movement of water from where the water potential is greater to where it is lower through a partially permeable membrane.  I specialise in A-level Biology so if you need anything else give me a shout :0)

Osmosis is the net movement of water from an area of higher concentration or water potential to an area of lower water concentration, through a semi- or partially permeable membrane. This is the process by which water enters the roots of plants.

Osmosis will take place until the concentration of water is the same on both sides of the membrane.

Osmosis is the net movement of water from an area of high concentration to an area of low concentration through a partially permeable membrane.  I know that definition can be quite confusing at first but if you break it down it becomes much more simple.  

A partially permeable membrane is like a set of doors, if you are smaller than the doors (water) you can get through whereas if you are to big (sugar, salt etc.) you are stuck where you are.

The mWater moves from an area where there is alot of it to where there is less.

Water moves from an area where there is alot of it to where there is less.

Osmosis is the net movement of water molecules from an area of higher water potential to an area of lower water potential across a selectively permeable membrane.

Osmosis is simply the movement of water molecules from a higher water potential to a lower water potential through a concentration gradient and they diffuse. 

Osmosis is the movement of water molecules from an area of high concentration of water to an area of low concentration of water through a partially permeable membrane. 

Basically, water moves from a place where there is lots of water to a place where there is not much water. Hope this helps!

Footer Graphic