Diffusion and osmosis Flashcards
Define diffusion
The movement of gases or dissolved molecules from an area of high concentration to an area of low concentration until an equilibrium is reached
Do you cell membranes let anything through?
No. They are selectively permeable
How does concentration affect diffusion
The higher the concentration gradient, the quicker /higher the rate of diffusion
How does diffusion distance affect diffusion
The larger the diffusion distance, the lower the rate of diffusion
What happens to molecules when there is an equal concentration
There is no net movement
What is osmosis
The movement of water molecules from an area of high water potential/concentration to an area of low water potential/concentration across a selectively permeable membrane
What happens when a plant cell is inside a solution with a very high sugar concentration
Cell wall is rigid so can’t move you but everything inside (cytoplasm and vacuole) shrink-cell becomes plasmolysed
What happens when you put an animal cell inside a solution with a very high sugar concentration
What leaves cell by osmosis-cell shrinks and become flaccid
What does isotonic mean
Same concentration
What does hypertonic mean
Higher concentration
What does hypotonic mean
Lower concentration
What is facilitated diffusion
The movement of a molecule from an area of high concentration to an area of low concentration with the help of a channel or carrier protein
Eg glucose, amino acids, ions
What is passive transport
The movement of molecules through a cell membrane down a concentration gradient without the use of energy (diffusion, facilitate diffusion, osmosis…)
What is active transport across membranes
The movement of molecules through cell membranes against a concentration gradient. This requires energy and carrier proteins e.g. glucose, amino acids ions
