Water potential Flashcards
what does a solution consist of?
A solution consists of a solute dissolved in a solvent.
Why is water a very good solvent?
Water is a very good solvent as it is dipolar meaning the hydrogen side of the molecule is slightly positive while the oxygen side is slightly negative.
what is solvation?
solvation is the interaction between a solvent and a solute.
how are hydration shells created around each solute particle?
hydration shells are created around each solute particle as polar solvents can orientate themselves toward polar solutes and ions to form hydrogen bonds or ion dipole forces.
what are all cells surrounded by?
all cells are surrounded by a cell membrane which is partially permeable.
how can water move in and out of cells?
by osmosis.
what is osmosis?
osmosis is the diffusion of water molecules from a less concentrated (dilute) solution to a more concentrated solution across a partially permeable membrane.
what does water move down?
water moves down a contraption gradient.
what does a partially permeable cell membrane allow?
a partially permeable cell membrane allows small molecules like water through but not larger molecules like solute molecules.
what is a hypotonic solution?
a hypotonic solution is one with a lower solute concentration meaning its diluted.
what happens when a cell is placed in a hypotonic solution?
when a cell is placed in a hypotonic solution (diluted), there will be a net movement of water molecules into the cell by osmosis.
what is a hypertonic solution?
a hypertonic solution is one that has a higher solute concentration (more concentrated).
what happens when a cell is placed in a hypertonic solution?
when a cell is placed in a hypertonic solution, there will be a net movement of water molecules out of the cell.
what is an isotonic solution?
an isotonic solution is one where there is a similar concentration as the cytoplasm of the cell.
what happens when a cell is placed in an isotonic solution?
when a cell is placed in an isotonic solution, there will be no net movement of water into or out of the cell by osmosis.
-but there are always water molecules moving into and out of the cells due to the kinetic energy that the molecules possess. there is movement just no net movement.
when is a cell in dynamic equilibrium?
a cell is in dynamic equilibrium with the isotonic solution as the movement of water into the cell will be balanced out by the movement of water out of the cell (no NET movement).
why is it important for animal cells to maintain their osmotic concentration?
it is important for animal cells to maintain their osmotic concentration as any deviations from this equilibrium may cause the cell to shrink to burst (no cell wall).
why are the results of osmosis more severe on animal cells?
because they do not have a supporting cellulose cell wall.
what happens when an animal cell is placed in a hypertonic solution(high conc)?
when an animal cell is placed in a hypertonic solution, water moves out of the cell by osmosis causing it to become crenated.
-can cause blood clots as crenated red blood cells may become stuck while moving through capillaries.
what happens when an animal cell is placed into a hypotonic solution (dilute)?
when an animal cell is placed into a hypotonic solution, water moves into the cell so it gains water by osmosis and as it has no cell wall to create turgor pressure, the pressure increases until the cell membrane is stretched to far and bursts.
what kind of environment do amoeba’s live in? what happens?
amoeba’s live in freshwater aquatic habitats that is hypotonic to their cytoplasm.
there will be a constant net influx of water into the organism by osmosis, which increases the internal pressure.
what structures do amoeba’s contain that prevents them from bursting?
they contain contractile vacuoles in their cytoplasm meaning excess water will be continuously collected in the contractile vacuole and pumped out of the organism to maintain their osmotic concentration.
what happens as water enters the vacuole of the plant cell?
as water enters the vacuole of the plant cell, the volume of the plant cell increases.
what is the protoplast?
the protoplast is the living part of the cell inside the cell wall.
what is turgor pressure?
turgor pressure is when the expanding protoplast pushes against the cell wall and pressure builds up inside the cell.
what prevents a plant cell from bursting?
the inelastic cell wall prevents the cell form bursting. It also creates pressure and stops too much water from entering.
when is a plant cell fully turgid?
a plant cell is fully turgid when it has become fully inflated with water and has become rigid and firm.
why is the turgidity of plants important?
the turgidity of plants is important as the effect of all the cells in a plant being firm is to provide support and strength for the plant - making a plant stand upright with its leaves held out to catch sunlight.
what happens if plants do not receive enough water?
if plants do not receive enough water, the cells cannot remain rigid and firm (turgid) and the plant wilts.
what is plasmolysis?
plasmolysis is the process of the protoplast gradually shrinking and no longer entering pressure on the cell wall. As it continues to shrink, it pulls away from the cell wall. The plant cell becomes flaccid and is said to be plasmolysed.
how are isotonic solutions used in medicine?
-patients may require an intravenous (IV) drip to treat dehydration or to deliver medicine directly into the bloodstream. The solution in the IV drip is isotonic in relation to blood plasma.
-donated human organs that will be used for transplant surgery must be kept in an isotonic saline solution to prevent damage to the cells due to the net movement of water by osmosis.
