"...where the pull of gravity is nearly zero": No it's not! This is sloppy science journalism physics where there's a gravity shield around Earth. The pull is there but objects are in free fall.
How Do Plants Know Which Way Is Up And Which Way Is Down?
21–25 of 25 posts
Re: How Do Plants Know Which Way Is Up And Which Way Is Down?
#22There was a bit of a non sequitur at the end, where they mention that the statolith theory has support from plants growing in space. That's no confirmation for the theory, we already knew they sensed gravity, the question is how they sense it.
Right. The experiment does nothing to confirm the conjecture. A neat trick would be, say, to figure out how to line up the statholiths (sp?) in zero g and see what happens relative to a plant whose statholiths are randomly arranged.
Note that ultimately we would like to come up with ways to convince human bodies that they're in a gravitational field, so this is not entirely academic.
Re: How Do Plants Know Which Way Is Up And Which Way Is Down?
#23I 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?
For the sunlight part: sunlight inhibits growth on the sun-facing side of the plant, and so the flower faces towards the sun.
Except this works for buried seeds and seeds germinated in the dark.
Re: How Do Plants Know Which Way Is Up And Which Way Is Down?
#24"...where the pull of gravity is nearly zero": No it's not! This is sloppy science journalism physics where there's a gravity shield around Earth. The pull is there but objects are in free fall.
"would the plants respond to the centrifugal pull of gravity"
Sometimes I have to reread sentences like this to get what the author is trying to convey. I don't understand why the author didn't leave it at "centrifugal pull. " It's already an adequate layman's term. A sentence like this only serves to confuse and make physics sound harder than it is. If a good teacher can open kids eyes to the wonders of the world, a bad teacher can easily fog the world in obscurity and inconsistencies.
Re: How Do Plants Know Which Way Is Up And Which Way Is Down?
#25There was a bit of a non sequitur at the end, where they mention that the statolith theory has support from plants growing in space. That's no confirmation for the theory, we already knew they sensed gravity, the question is how they sense it.
Learned about statoliths in university. Didn't realize the statolith theory was up for debate.