2. transport across cell membranes Flashcards
what is the cell membrane made up of?
phospholipids and proteins
if a cell membrane is selectively permeable…?
it will only allow the passage of smaller, soluble molecules through the membrane
what is diffusion?
the movement of molecules from an area of higher concentration to a lower concentration down a concentration gradient - it is a passive process
why is diffusion important to cells?
cells require glucose and oxygen to diffuse into them so they can make energy (aerobic respiration) , waste product CO2 must diffuse out of cells so they can stay alive
what is osmosis?
the movement of water molecules from an area of higher water concentration to a lower water concentration through selectively permeable membrane - it is a passive process
describe a turgid cell?
the vacuole has swollen because water has moved into it by osmosis, the cytoplasm is pushed against the wall, cell wall stretches to a maximum
describe a plasmolysed cell
vacuole shrinks because water has moved out by osmosis, cytoplasm is pulled away from the cell wall, the cell wall is unstretched
if a plant cell is placed in a high water/low salt concentration it is?
turgid
if a plant cell is placed in a low water/high salt concentration it is?
plasmolysed
what is plasmolysis?
the process of extreme water loss in a plant cell
what is active transport?
the movement of ions and molecules from a lower concentration of ions to a higher concentration against a concentration gradient - through a cell membrane
what process requires energy?
active transport
what process doesn’t require energy?
diffusion, osmosis
