Diffusion Flashcards
When does diffusion stop?
When an equilibrium (same concentration in and out of the cell) is reached.
What is diffusion?
The net movement of molecules from a higher concentration to an area of concentration, moving down a concentration gradient until and equilibrium is reached.
Does diffusion require energy?
No it is a passive process.
When does diffusion occur?
As molecules randomly using their own kinetic energy both ways across a membrane.
What happens at equalibrium?
Diffusion will occur at the same rate in both directions.
What molecules can go through simple diffusion?
-Lipid-soluble
-Non-polar molecules
-Water
What does Fick’s law state can increase the rate of diffusion?
-Larger surface area
-Bigger concentration difference
-A short diffusion pathway
-Temperature
How is the rate of diffusion to stop plants losing water?
-Plants have guard cells.
-Waxy layer on plants.
How is diffusion present in the alveoli and how is it adapted to increase the rate of diffusion?
-Gas exchange of CO2 and 02.
-Only 1 tissue layer thick so short diffusion pathway.
-Good blood supply, large concentration difference.
-Has ‘air sacs’ for large surface area.
How is intestinal villus adapted for a quicker rate of diffusion?
-Diffuses molecules from food back into the body.
-Covered in lots of microvilli so large surface area.
-Good blood supply so large concentration difference.
-1 cell thick, short diffusion pathway.
What other molecules does facilitated diffusion require?
Carrier and channel proteins.
What molecules have to go through facilitated diffusion?
-Large water-soluble
-Polar molecules
How do carrier proteins allow larger molecules to pass through the membrane?
Physically change shape to allow molecules to pass through
When does facilitated diffusion stop?
When all proteins are saturated (full).
