Osmosis Flashcards
What are partially permeable membranes?
They allow small particles and molecules to pass through but not large molecules like sugar
How is osmosis different from diffusion?
It is a special type of diffusion
Diffusion is when particles can spread freely
Osmosis is when substances pass through a partially permeable membrane
Partially permeable membranes let water move across them. Water moves across from dilute solution to a concentrated solution
What is isotonic?
When the concentration inside and outside the cell is the same as the solution
What is hypertonic?
When the concentration of solutes outside the cell is higher than the internal concentration of the cell
What is hypotonic?
When the concentration of solution outside the cell is lower than the internal concentration of the solution
How does osmosis work in animal cells - hypotonic?
If a cell uses up water the cytoplasm becomes more concentrated. The surrounding fluid becomes hypotonic to cell and more water moves in by osmosis
How does osmosis work in animals - hypertonic?
If the cytoplasm is too dilute because more water is made in chemical reactions the surrounding fluid becomes hypertonic to the cell and water leaves by osmosis to restore balance
What is the problem of osmosis - hypotonic?
If the surroundings are more dilute than the cell contents water moves in by osmosis and the cell will swell and may burst.
What is the problem of osmosis - hypertonic?
If the solution outside the cell surroundings is more concentrated then the water moves out by osmosis and cytoplasm will become too concentrated and cell will shrivel up and cannot survive
How does osmosis work in plants?
Key to whole way of life
Supports stems and leaves as water moves into plant cells
Vacuole swells
Cytoplasm presses against cell wall
Pressure builds until no more water can get in - turgor
Turgor makes cells hard, rigid and keeps stems and leaves firm
Plants need surroundings to be hypotonic
If it is hypertonic water leaves by osmosis and cells become flaccid, turgor no longer supports plant tissue
What is plasmolysis?
If too much water is lost by osmosis the vacuole and cytoplasm shrink and eventually the cell membrane falls away from the cell wall.
Usually only seen in experiments
Cells die quickly unless osmotic balance is restored balance
What is osmosis?
The movement of particles from an area of high concentration to one of lower concentration
It is the move to of water across a partially permeable membrane
What is flaccid?
If the solution surrounding the plant cell is hypertonic to the cells contents , the water will leave the cell by osmosis
The cell will no longer be firm and swollen and become soft and flaccid
