Cells Flashcards
What is diffusion
Diffusion is the movement of molecules from an area of high concentration of the molecules to an area with low concentration down a concentration gradient
What happens to molecules during diffusion
During passive diffusion a molecule simply dissolves in the phospholipid bilayer diffusion across it and then dissolves in the aqueous solution at the other side of the membrane
How does diffusion happen
Diffusion happens when molecules of gas or liquid spread out.
Does diffusion require energy
Diffusion doesn’t require energy as it is a passive process
How does oxygen move into cells
Oxygen moves into the cells by diffusion and diffuses across the cell membrane
How does carbon dioxide move out of cells
Carbon dioxide moves out of cells by diffusion and diffuses across the cell membrane
What is a selectively permeable membrane
A semi permeable membrane will let molecules pass through if they are small enough. Larger molecules cannot pass through the pores in the membrane
What membrane is the cell membrane
The cell membrane is a semi permeable membrane
Remember!
During experiments, the visking tubing can be used as a model of the cell membrane. The pore size in visking tubing is large enough to allow small molecules through such as iodine or water molecules. SOLUTES molecules such as starch are too large to pass through
What is meant by the term semi permeable membrane
It allows small/ smaller molecules to pass through
Identify which molecules pass through the visking. Explain your answer
The small balls can pass through but the big balls are too big for them to fit through the visking tubing
Explain why the colour of the contents inside the visking tubing turned blue/black
Iodine is small.
Diffuses into visking tubing.
Reacts with starch which is presented to give the blue and black colour
Explain why the colour of iodine solution in the boiling tub did not change.
Start is large. Cannot pass through the membrane or fit through the pores
Name one substance required for respiration that would pass through into a cell
Oxygen or glucose
Write down one way that diffusion and osmosis are similar
They both are from a high to a low concentration gradient
