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TROPIC RESPONSES. Merighi Pietro. What is a Geotropism ?. A geotropism is the growthof living plants in response to gravity . It is given by the downward of the plant roots. What is a Phototropism ?.

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tropic responses


Merighi Pietro

what is a geotropism
Whatis a Geotropism?
  • A geotropismis the growthof living plants in responsetogravity.
  • Itisgivenby the downwardof the plantroots
what is a phototropism
Whatis a Phototropism?
  • Itis the directionalgrowth in which the direction of the growthisdeterminedby the direction of the light source.
  • In otherwordsitis the growth and responseto a light stimulus.
plant auxins
  • As withanimals , plantsalsouse a varietyofhormonestocontroltheirgrowth and development. A family ofhormonescalledauxins are commonlyfound in plants, and promote (and sometimesinhibit) growth.
what are auxins
What are Auxins?
  • Auxins are produced in the meristems (tissuethatgrows) ofplants
  • Auxins are responsibile in promotingcellelongation, a processthatisrequiredbeforedifferentiationof a cell. Itisabletothisbypromoting the intakeof water, increasing the elasticityof the celltocopewith the increaseof water taken in by the cell.
  • (Oneof the most common auxinsis indole acetic acid.)
phototropism in auxins
Phototropism in Auxins.
  • Auxinsalso play a part in phototropism, anoccurancethayinvolvesplantsbending or movingawayfrom light. The shoottipisresponsiblefordirectionalmovementby the plant in responsetosunlight, asthisis the area whereauxins can befound.
  • Sunlighteradicatesauxin, meaningthat the part of the shoottipof the plantwhichisreacivingdirectsunlightwilhave the leastamountofauxin
  • The extra auxinpresent on the shaded side promotes more celldivision and elongation, causing the planttobendtowards the sunlightafterthislop-sidedgrowth.
geotropism in auxins
Geotropism in Auxins.
  • Geotropismis a similaroccuranceto the phototropismwhere the plantexihibitsdirectionalgrowth in responsetogravity. The shoottipillustrates negative geotropism (growsagainstforceofgravity) while the roottipexhibits positive geotropism (grows in the same direction asgravity).
  • Whatis a geotropism and a phototopism?
  • What are Auxins?