Cells and movement across membranes

Diffusion, Visking tubing model, osmosis and active transport ~ See blended laerning 1.1, cognito.edu youtube, and bbc bitesize

What is diffusion?

Movement of molecules down a concentration gradient

What kind of process is diffusion?

Passive

Does diffusion require energy?

No

What is a selectively permeable membrane?

Membrane which only allows some molecules to pass through its pores

What is visking tubing used as a model of?

Cell membrane

What is osmosis?

Diffusion for water

What is the difference between diffusion and osmosis?

Diffusion is most molecules, osmosis is water only

Describe the common test for osmosis

1. Cut potatoes into cylinders

2. Blot dry and weigh

3. Place potato cylinders in salt solution for a few hours

4. Blot and weigh

What does active transport do?

Moves molecules from a low concentration to a high concentration against the concentration gradient

What does active transport need to work?

ATP

Where is active transport used?

Protein carriers taking in molecules to the cell

What is a common adaptation of a cell that uses active transport?

More mitochondrion