osmosis Flashcards
osmosis
the movement of water from a dilute solution to a concentrated solution through a partially permeable membrane
partially permeable membrane
a membrane with very small holes that only allows certain molecules e.g water to pass through and bigger molecules e.g sucrose can’t
why do water molecules pass both ways through the membrane?
water molecules move about randomly all the time
why is there a steady net flow of water into the region with fewer water molecules (into the stronger sucrose solution)
because there are more water particles on one side than the other
does osmosis require energy?
no-it is passive
hypotonic
lower solute concentration outside cell
hypertonic
higher solute concentration outside cell
isotonic
having the same solute concentration inside and outside the cell
give two examples of osmosis
- plants absorbing water from the soil
- reabsorption of water in the kidneys
what might happen when an animal cell is placed into a very hypotonic solution?
water moves into the cell causing it to burst
what might happen when an animal cell is placed into a very hypertonic solution?
water moves out of the cell causing it to shrivel up
how do plant leaves and stems remain rigid?
turgor pressure-water moves in by osmosis, causing the vacuole to swell and cytoplasm to press against the cell wall
what might happen when an plant cell is placed into a very hypertonic solution?
water moves out of the cell by osmosis and the vacuole and cytoplasm decrease in size, cell membrane may pull away from the cell wall causing the cell to be plasmolysed
will water move into a cell that has a higher or lower concentration of sugar solution?
higher concentration
does water move in or out of the cell in a hypertonic solution?
it moves out
