Naked Science Forum

Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: paul.fr on 26/10/2007 19:06:54

Title: how do flowers follow the sun?
Post by: paul.fr on 26/10/2007 19:06:54

how do they bend, and turn, to follow the sun?

Title: how do flowers follow the sun?
Post by: Alandriel on 26/10/2007 20:40:21

If you have 5 mins to spare, watch this (http://www.youtube.com/watch?v=rXn_wHE1UBY)
You don't see how the actual flower 'seeks' the light, but the whole plant as it grows.

How? I'd like to know too. Photosensitive, but exactly how I have no idea

Title: how do flowers follow the sun?
Post by: RD on 01/11/2007 12:32:46

Quote from: paul.fr on 26/10/2007 19:06:54

how do they bend, and turn, to follow the sun?

Quote

Phototropism is enabled by auxins. Auxins are plant hormones that have many functions. In this respect, auxins are responsible for expelling H+ ions (creating proton pumps) which decreases pH in the cells on the dark side of the plant. This acidification of the cell wall region activates enzymes known as expansins which break bonds in the cell wall structure, making the cell walls less rigid. In addition, the acidic environment causes disruption of hydrogen bonds in the cellulose that makes up the cell wall. The decrease in cell wall strength causes cells to swell, exerting the mechanical pressure that drives phototropic movement.

http://en.wikipedia.org/wiki/Phototropism

Title: how do flowers follow the sun?
Post by: Andrew K Fletcher on 01/11/2007 15:09:18

If it caused disruption in the hydrogen bonds, surely it would cause cavitations in the sap beads also as the hydrogen bonds would also be weakened there. Besides to suggest that acids can cause the plant to follow the energy of the sun and then when the acid has presumably been replaced by? The plant during the night relaxes in the correct place for the sun to rise again? What happens when evaporation takes place and there is no energy from the sun, say a cloudy day?


Humbug! What we need is an explanation for a more instantaneous reaction to the energy source that can explain how plants are manipulated and the only explanation that can address this must be one that does not rely on slow chemical reactions but relies on hydraulic pressures generated by falling solutes suspended in the sap.

Title: how do flowers follow the sun?
Post by: sandyewillson on 19/03/2010 13:32:19

Thanks for the explanation dude, it's very clarify the doubts if any one had the doubt regarding this