a) Explain how the following blood cells are adapted to their functions. b) Explain the different ways in which Carbon (IV) Oxide is transported by blood

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a)    Explain  how  the  following  blood  cells  are  adapted  to  their  functions

 i)  Red  Blood  Cell
 Presence  of  haemoglobin  molecules;  with  a  high  affinity  to  combine  with  oxygen  as/to  form oxyhaemoglobin;  bi-concave  shape;  to  increase  the  surface  area  for  packaging  of haemoglobin;  absence  of  nucleus;  to  accommodate  maximum/more  haemoglobin molecules;  thin  membrane;  for  faster  diffusion  of  gases;  Max.  6  mks

 ii)  White  blood  cell
 Irregular  in  shape/amoeboid;  which  changes  to  enable  the  cell  to  squeeze  through  the capillaries;  lymphocytes  produce  antibodies;  which  help  to  prevent  diseases;  phagocytes  are amoeboid-shaped;  to  change  shape  and  engulf  bacteria  cells;  Max.  6  mks

 b)  Explain  the  different  ways  in  which  Carbon  (IV)  Oxide  is  transported  by  blood
Carbon  (IV)  oxide  diffuses  out  of  the  tissues  into  the  red  blood  cells  where  it  reacts  with water;  in  the  presence  of  carbonic  anhydrase  enzyme;  to  produce  carbonic  acid;  The  acid dissociates  into  hydrogen  and  hydrogen  carbonate  ions;  the  hydrogen  carbonate  ions  then diffuse  out  of  the  red  blood  cells  into  the  plasma;  where  it  further  dissociates  to  produce carbon  (IV)  oxide  on  reaching  the  alveolar  cavities  of  the  lungs  and  diffuses  into  the  alveoli; some  carbon  (IV)  oxide  combines  with  the  amine  group  in  the  haemoglobin  molecule forming  carbaminohaemoglobin;  which  dissociates  in  the  lungs  producing  carbon  (IV)  oxide; some  carbon  (IV)  oxide  dissolves  in  the  blood  plasma  forming  carbonic  acid,  which dissociates  to  carbon  (IV)  oxide  on  reaching  the  lungs;  Max.  8  mks 

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