7 Exchange surfaces Flashcards
equation of Fick’s Law (rate of diffusion)
rate of diffusion = Area of diffusion surface * difference in concentration / Thickness of surface over which diffusion takes place.
What is osmosis
The diffusion of water across a partially permeable membrane
What is water potential + its measure
The pressure exerted by water molecules as they collide with a membrane or container
Pascals (Pa)/ Kilopascals (KPa)
What is the water potential of pure water
0 KPa
What happens to the water potential when a solute is added
Lowers the water potential
Are all solutions negative or positive water potentials?
Negative
The more concentrated the solution the more …… the water potential (what is ……)
Negative
information flashcard
When solutions of different concentrations (different water potentials) are separated by a partially permeable membrane the water molecules can move between solutions but the solutes usually cannot. There will then be a net movement of water from the solution with HIGHER water potential (less concentrated) to the solution with the LOWER water potential (more concentrated). This will continue until the water potential on both sides of the membrane is equal (equilibrium).
What is a pinocytosis
liquid
what is a phagocytosis
Solid
what is a hypOtonic solution
lOwer sucrose
higher water potential
What is a hypERtonic solution
HighER sucrose
lower water potential
In osmosis does the water move from a hypotonic solution to a hypertonic solution
HypOtonic —> HypERtonic
Why can single celled organisms use diffusion alone
Low metabolic rate
large SA:V ratio
What organisms can use diffusion through the cell surface
Amoeba