osmosis Flashcards
define osmosis
the net movement of water molecules from a region of high water potential to a region of lower water potential through a partially permeable membrane
what is water potential
the tendency of water molecules in a system to move
how does solutes affect the water potential
the amount of solutes
the greater the amount of solutes, the lower the water potential
water molecules bind to the solute molecules, reducing the number of water molecules that are free to diffuse
define hydrostatic pressure
a pressure that a fluid exerts when pushed against a membrane/container
what happens to animal cells in higher water potential
cell surface membranes cannot stretch to withstand increased pressure
burst [cytolysis]
what happens to animal cells in lower water potential
cell will lose water
crenation
define hypertonic
sol that is more concentrated, lower water potential
define isotonic
sol that has the same concentration, same water potential
define hypotonic
sol that is less concentrated, higher water potential
what is the pressure against cell wall called
turgor
what happens to the plant cell when turgor pressure changes
increase = resists entry of further water into the cell, cell becomes turgid
decrease = water is lost by osmosis, cell become plasmolysed
define plasmolysis
the protoplast pulls away from the cell wall
what happens to plant cell when placed in hypertonic solution
net movement of water by osmosis is out of the cell, protoplast shrinks
protoplast pulled completely away from the cell wall and the cell is fully plasmolysed {flaccid}
what happens to plant cells when being placed in an isotonic solution
cells displays incipient plasmolysis, membrane os just beginning to pull away from to the cell wall
no net movement of water, no pressure potential, protoplast ceases to press against the cell wall
what happens to plant cells in hypotonic solution
the net movement of water by osmosis is into the cell, protoplast swells and presses against the cell wall
cell is fully turgid
