4.2 diffusion

Question 1

definition of diffusion

Answer 1

net movement of molecules/ions from a region of high concentration to a region of lower concentration until evenly distributed

Question 2

what is the difference between facilitated & simple diffusion?

Answer 2

simple - passive, energy comes from inbuilt motion
facilitated - active, requires protein channels / carrier proteins

Question 3

explain how protein channels work.

Answer 3

• intrinsic protein
• allows water-soluble ions
• selective transport; only allow a specific ion
• ions bind to protein which changes its shape & opens side

Question 4

explain how carrier proteins work.

Answer 4

molecules bind to specific proteins -> changes shape and release to inner membrane