Question

Explain how the various specialized cells are modified to carry out their functions in plants and animals

Answer 1

1. Animal cell
   • Sperm  cell;  has  acrosome  containing  lytic  enzymes;  that  digest  the  egg  membranes for  penetration  during  fertilization;  has  a  long  tail;  containing  numerous  mitochondria;  to generate  maximum  energy  for  propulsion/swimming  in  the  vaginal  fluid  after  ejaculation;  
   • Red blood  cells;  are  flattened,  circular/spherical  biconcave  in  shape;  to  increase  the  surface  area  for packaging  of  haemoglobin;  has  haemoglobin;  that  combines  with  respiratory  gases;  for  transport to  and  from  body  tissues;  
   • White  blood  cells;  are  amoeboid  in  shape  hence  able  to  change  shape; to  engulf  pathogens  through  phagocytosis;  lymphocytes  produce  antibodies  to  fight  pathogens; 
   • Nerve  cell;  has  extensions/dentrites;  to  receive  and  send  information  for  sensation;  Ciliated epithelial  cells;  have  cilia  for  propulsion  of  mucus  that  traps  dust  and  micro-organisms  in  the respiratory  tract;  
   • Muscle  cells;  elongated,  striated  and  contractile;  to  bring  about  movement; 
2. Plant  cells:  
   • Guard  cells;  bean-shaped;  to  regulate  the  size  of  the  stomata  allowing  gaseous exchange;  and  control  water  loss;  has  chloroplasts  with  chlorophyll;  for  photosynthesis;  
   • Root hair  cell;  elongated;  thin-walled;  with  dense  cytoplasm  for  absorption  of  water  and  mineral  salts;
   • Epidermal  cell;  thin;  for  protection  of  inner  tissues  from  mechanical  and  micro-organism  attack; 
   • Palisade  cell;  contains  numerous  chloroplasts  with  chlorophyll;  for  photosynthesis;  elongated;  to increase  surface  area  for  trapping  maximum  amounts  of  light  energy;  
   • Meristematic  cell;  thinwalled;  with  dense  cytoplasm;  for  primary  and  secondary  growth;