a Complete the following table.  
  Simple Diffusion Facilitated Diffusion Active Transport
From High to Low concentration yes yes no
Requires ATP no no yes
Transport through intrinsic membrane proteins no yes yes
Can be controlled by cell no yes yes
  note 1 mark for each fully correct row (4)
b Describe a cell capable of taking up glucose (a monosaccharide) by active transport may be incapable of taking up fructose (another monosaccharide) by active transport  
  • Active transport requires carrier proteins;
  • These proteins have a specific shape/tertiary structure
  • which can only fit glucose
  • fructose does not fit/shape incompatible