How Do Plants Know Which Way Is Up And Which Way Is Down?
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Re: How Do Plants Know Which Way Is Up And Which Way Is Down?
#2I seem to remember learning the pecise reason why plants both respond to sunlight and to gravity during my Freshman year Biology class in high school. I remember that it is due to a single plant hormone that stunts the elongation of cells. I think it begins with an 'a'.
Aren't the mechanics of this well-known?
Re: How Do Plants Know Which Way Is Up And Which Way Is Down?
#3I seem to remember learning the pecise reason why plants both respond to sunlight and to gravity during my Freshman year Biology class in high school. I remember that it is due to a single plant hormone that stunts the elongation of cells. I think it begins with an 'a'. Aren't the mechanics of this well-known?
Auxin, I did a science project on this in 5th or 6th grade. My father helped me rig up a centrifuge-like apparatus that would spin seeds at what was supposed to simulate greater than earth gravity. I remember doing research (reading) about auxins and coming to the conclusion that higher gravity would stunt plant height.
Re: How Do Plants Know Which Way Is Up And Which Way Is Down?
#4I seem to remember learning the pecise reason why plants both respond to sunlight and to gravity during my Freshman year Biology class in high school. I remember that it is due to a single plant hormone that stunts the elongation of cells. I think it begins with an 'a'. Aren't the mechanics of this well-known?
Auxin, I did a science project on this in 5th or 6th grade. My father helped me rig up a centrifuge-like apparatus that would spin seeds at what was supposed to simulate greater than earth gravity. I remember doing research (reading) about auxins and coming to the conclusion that higher gravity would stunt plant height.
And what happened to the seeds on your science project? :)
Re: How Do Plants Know Which Way Is Up And Which Way Is Down?
#5I think it's just a function of how the liquid in the plant's cells settled by gravity. The denser liquid is pulled to the bottom by gravity while thinner liquid floats to the top. The plant must grow toward the thinner liquid, away from gravity.
Re: How Do Plants Know Which Way Is Up And Which Way Is Down?
#6I'm surprised that the plant was robust in space. It could just as well have stopped growing at all. Makes you wonder if there are any low gravity growth places on earth. If not, where has the plant learned this skill?
Re: How Do Plants Know Which Way Is Up And Which Way Is Down?
#7I'm surprised that the plant was robust in space. It could just as well have stopped growing at all. Makes you wonder if there are any low gravity growth places on earth. If not, where has the plant learned this skill?
I'm not sure if you're joking, but you should know that I had a good laugh at this comment. :) In case you are indeed wondering, gravity has no effect on cell growth, or indeed on any of the cell's vital functions. More than anything, cellular processes rely on chemical diffusion, which at that scale is more strongly affected by temperature than by gravity.
Also, gravity is almost constant everywhere on the earth's surface.
Re: How Do Plants Know Which Way Is Up And Which Way Is Down?
#8Some bacteria know up and down by knowing magnetic north and south. They take advantage of the fact that magnetic north usually points slightly down or up.
By knowing up and down the bacteria can move to the area with optimal parameters like temperature/oxygen saturation - these usually change with depth.
Re: How Do Plants Know Which Way Is Up And Which Way Is Down?
#9I think it's just a function of how the liquid in the plant's cells settled by gravity. The denser liquid is pulled to the bottom by gravity while thinner liquid floats to the top. The plant must grow toward the thinner liquid, away from gravity.
While this sounds plausible, it doesn't explain how roots grow downwards.
Re: How Do Plants Know Which Way Is Up And Which Way Is Down?
#10did not click cause of one obvious word: gravity