AP Biology - 2.8 Tonicity and Osmoregulation

water moves by osmosis from a _(1)_ to _(2)_ solute concentration

(1) low to (2) high

define osmolarity:

total solute concentration in a solution

water moves by osmosis from a _(1)_ to _(2)_ osmolarity

(1) low to (2) high

water moves by osmosis water moves by osmosis from a _(1)_ to _(2)_ water potential

(1) high to (2) low

define tonicity:

measurement of the relative concentrations of solute b/w 2 solutions (inside and outside of the cell)

what are the three ways an internal cellular environment can act towards the external environment?

hypotonic, hypertonic, isotonic

ID hypertonic CELL:

more solute, less solvent

ID hypotonic CELL:

less solute, more solvent

ID isotonic CELL:

equal solute + solvent concentration

how are the water and solute concentration related?

inversely

water diffuses from a what to what environment?

hypotonic to hypertonic

solute diffuses from a what to what environment?

hypertonic to hypotonic

in a higher solute concentration in water, there are —(1)— water molecules and a —(2)— water potential

(1) less and (2) low

in a lower solute concentration in water, there are —(1)— water molecules and a —(2)— water potential

(1) more and (2) high

what is dynamic equilibrium?

state of water when there is an equal concentration of water on both sides of the membrane

how do osmoregulatory mechanisms contribute to survival?

• growth and homeostasis are maintained by the constant movement of molecules across the membrane

• maintains water balance

• organisms control internal solute composition/water potential

ID the effect of environmental hypotonicity (in solution) in an animal cell:

• more solute within cell, less solute outside

• water coming in

• cell = lysed

ID the effect of environmental hypertonicity (in solution) in an animal cell:

• less solute within cell, more solute outside

• water leaving

• cell = shriveled

ID the effect of an isotonic solution in an animal cell:

• equal solute and equal solvent

• water coming in and out

• cell = normal

ID the effect of environmental hypotonicity (in solution) in a plant cell:

• more solute within cell, less solvent outside of cell

• water coming into cell

• cell = normal

ID the effect of environmental hypertonicity (in solution) in a plant cell:

• less solute within the cell, more solute outside of cell

• water leaving the cell

• cell = plasmolyzed (cell wall is ripping away)

ID the effect of an isotonic solution in a plant cell:

• equal solute and solvent

• water coming in and leaving

• cell = flaccid

why are plant cells normal in a hypotonic solution?

• when water flows into the plant vacuoles, the vacuole will be expand and press against the cell wall

• cell wall will expand until it exerts pressure back on the cell

• turgor pressure

define turgidity:

• the optimum state for plant cells

what is water potential?

measures the tendency of water to move by osmosis

what is the water potential of pure water?

0

what is the pressure potential of an open beaker solution?

0

an increase in solute has what effect on the solute and water potential?

• decreased solute potential

• decreased water potential

an increase in water potential has what effect on the pressure potential?

• increased pressure potential

an increase in pressure potential has what effect on the water potential?

• increased water potential