4.1 Diffusion

Question 1

The movement of molecules from one location to another solely on their random thermal motion (second law of thermodynamics - from high concentration to low concentration) is known as:

Answer 1

Simple diffusion

Question 2

Simple diffusion is one of the key mechanisms by which cells maintain _____

Answer 2

Simple diffusion is one of the key mechanisms by which cells maintain homeostasis

Question 3

The amount of material crossing a surface in a unit of time is known as a

Answer 3

Flux

Question 4

What is the Net Flux?

Answer 4

The difference between two one-way fluxes

ie the net gain of molecules in one “compartment” per unit time and the net loss of molecules in the other “compartment” per unit time

In equilibrium, Net Flux will be 0

Question 5

When the net flux is zero, the system is said to be in?

Answer 5

Diffusion equilibrium

Question 6

Although movement of individual molecules is random, the net flux is always greater from regions of ______ ______ to regions of ______ _______

Answer 6

Although movement of individual molecules is random, the net flux is always greater from regions of higher concentration to regions of lower concentration

Question 7

________ difference determines both the direction and the magnitude of the net flux

Answer 7

Concentration difference determines both the direction and the magnitude of the net flux

Question 8

Aside from concentration, there are 4 additional factors that affect net flux:

Answer 8

1. Temperature: higher temp = faster movement = faster net flux
2. mass of the molecule: larger molecules (eg protein) move slower than smaller molecules = slower net flux
3. Surface area: the greater the surface are separating two regions, the greater the space available for diffusion (example one door in an auditorium vs multiple)
4. The medium through which the molecules are moving: molecules diffuse more rapidly through air than in water