Plant Physiology: Phototropic Response

Plant Physiology: Phototropic Response



growth in plants reflects the way in which they interact with the environment if we place a strong light at one side of this fuchsia plant the plant will grow towards it this is called a phototrophic response but what controls such a response if the tip of the plant is protected from the light using a small cap the plant will continue to grow upward this suggests that there is something at the tip of the plant that controls the direction of growth if we place this fuchsia plant on its side it quickly recovers its orientation and grows upward but is the plant responding to light or to gravity these pea seeds are germinating in the dark yet the roots are growing down and the shoots are growing up the roots and shoots must be responding to gravity but in different ways the roots are said to be positively geo tropic and the shoots negatively gia tropic it is probable that all of these growth responses are due in some part to the aux-in indole acetic acid or IAA one theory states that a light sensing mechanism in the tip of the fuchsia plant promotes the active transport of I am molecules to the shaded part of the stem this action produces cell growth and elongation in this area the result is a curvature which orientates the plant towards the light a gravity sensing mechanism in the shoot tip triggers a similar migration of IAA molecules producing growth in the stem which orientates the plant from a horizontal position back to a vertical position the growth substance IAA also appears to have a role in maintaining apical dominance by removing the growing tip which controls aux-in distribution and therefore apical dominance lateral buds grow an important hormone in deciduous plants is abscisic acid which controls leaf fall thereby protecting the plant from adverse seasonal conditions

3 thoughts on “Plant Physiology: Phototropic Response”

  1. @sensitiveplant Spam Fail.

    the plant is an inbred mimosa. Buy mimosa seeds, not this spammers products. You have no students, only customers.

  2. TickleMe Plant is a REAL plant that MOVES when you Tickle It!. The leaves instantly closes and even the branches droop when Tickled . Great for science projects. Google TickleMe Plant – My students love it

  3. If hope vegetarians watch this, plants really are living creatures and while they might not sense pain in the way you and I do, being alive still counts! If you think about it, what's worse, me eating an animal that's already dead, or you pulling a sprout out of the ground and eating it? I don't know… I honestly don't know!

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