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TROPIC RESPONSES

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

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  1. TROPIC RESPONSES Merighi Pietro

  2. Whatis a Geotropism? • A geotropismis the growthof living plants in responsetogravity. • Itisgivenby the downwardof the plantroots

  3. 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.

  4. PlantAuxins • As withanimals , plantsalsouse a varietyofhormonestocontroltheirgrowth and development. A family ofhormonescalledauxins are commonlyfound in plants, and promote (and sometimesinhibit) growth.

  5. 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.)

  6. 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.

  7. 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).

  8. Questions….. • Whatis a geotropism and a phototopism? • What are Auxins?

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