2.3.2: Diffusion

Question 1

Define diffusion

Answer 1

the net movement of molecules down a concentration gradient until an equilibrium is reached, this is a passive process that doesn’t require metabolic energy

Question 2

describe simple diffusion

Answer 2

passing directly between the phospholipids, properties must be non polar, lipid soluble, small. Can transport gases this way

Question 3

describe facilitated diffusion

Answer 3

passing through intrinsic proteins, properties must be polar, water soluble, large
channel proteins can transport ions, carrier proteins can transport glucose and amino acids

Question 4

name 6 factors that affect diffusion rate and state how

Answer 4

increased temperature -> increased rate
increased membrane fluidity -> increased rate
increased concentration gradient -> increased rate
increased diffusion distance -> decreased rate
increased lipid solubility -> increased rate
increased surface area -> increased rate

Question 5

describe the graph of concentration gradient against rate of diffusion for simple diffusion

Answer 5

straight line that increases in rate of diffusion as concentration gradient increases

Question 6

describe the graph of concentration gradient against rate of diffusion for facilitated diffusion

Answer 6

curved line that increases in rate of diffusion as concentration gradient increases, but eventually as concentration gradient increases, rate of diffusion increases slower gradually leading to the rate of diffusion to plateau as concentration gradient further increases

Question 7

explain the graph of concentration gradient against rate of diffusion for simple diffusion

Answer 7

as the concentration gradient increases the rate of diffusion increases because the rate of diffusion is determined by the concentration gradient

Question 8

explain the graph of concentration gradient against rate of diffusion for facilitated diffusion

Answer 8

initially as the concentration gradient increases the rate of diffusion increases because the rate of diffusion is determined by the concentration gradient. the latter part of the graph, as the concentration gradient further increases, the rate of diffusion remains constant (plateau), this is because the number and availability of transport proteins is a limiting factor

Question 9

what is a limiting factor of facilitated diffusion

Answer 9

number and availability of transport proteins