Diffusion, Osmosis and Tonicity

Question 1

What is diffusion?

Answer 1

Diffusion is an essential biological process which transports oxygen and carbon dioxide in and out of the bloodstream, as well as ions across cell membranes

Question 2

How does temperature affect diffusion?

Answer 2

Higher temp –> faster diffusion

Question 3

What causes diffusion?

Answer 3

Diffusion is caused by the random thermal motion of molecules
Occurs from region of high concentration to region of lower concentration

Question 4

How do you calculate root mean square distance (distance traveled by particle due to diffusion)?

Answer 4

x (rms) = sqrt(2 * diffusion constant ‘D” * time)

Question 5

How do you treat fluids that are a mixture of different molecules?

Answer 5

You treat each part of the fluid as if it is the only molecule present (for fixed total volume and temperature)
- each component produces ‘partial pressure’

Question 6

What is the relation between pressure and number of moles/molecules

Answer 6

Pressure is proportional to number of moles/molecules

Question 7

What is osmolarity?

Answer 7

Osmolarity is the number of moles (osmoles) of solute particles per litre of solution
units: osmol/L

Question 8

What is osmosis?

Answer 8

Osmosis is the net movement of solvent molecules through a semi-permeable membrane into a region of high osmolarity

Question 9

What is tonicity?

Answer 9

Tonicity is a measure of the osmotic pressure gradient