38. Discuss how the various tropisms adapt plants to their habitats .

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Phototropism;  growth  curvature  in  response  to  direction  of  light;  enables  plant  shoots  to  grow and  get  light  for  maximum  photosynthesis;  allows  for  leaf  mosaic;  Thigmotropism;  growth curvature  in  response  to  contact/hard  surface;  makes  plants  with  weak  stems  to  get  support  on large  plant/trees;  this  makes  them  to  reach  and  get  light  for  maximum  photosynthesis; Geotropism;  growth  curvature  in  response  to  gravity;  enables  plant  roots  to  grow  deep  into  the soil  for  maximum  support/anchorage;  Hydrotropism;  growth  curvature  in  response  to moisture/water;  water  is  then  used  as  a  raw  material  during  photolysis  stage  of  photosynthesis; Chemotropism;  growth  curvature  in  response  to  chemical  concentration  gradient;  enables pollen  tubes  to  grow  down  the  style  and  into  the  ovary  for  fertilization  to  occur  in  plant flowers;  Thermotropism;  growth  curvature  in  response  to  temperature  changes;  enables  plants to  grow  to  where  they  can  acquire  optimum  temperature  for  effective  plant  process  (e.g. sunflower  orientates  towards  the  direction  of  the  sun);  Max.  20  mks 

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