If you plant a seed in any position you'll notice that after a while it will come out at the surface as a sprout even if it has to bend it's roots to reach the surface. So, how do they know which way is the air and why don't they grow downwards (in the wrong direction) and die?
2007-03-17 20:54:12 · 7 answers · asked by Alexander 2 in Science & Mathematics ➔ Botany
plant cells contain a plant hormone called "auxin", which elongates cells, and is repelled by light.
no matter what orientation a seed is in, this auxin will try to escape light, therefore, say a seed is horizontal, all the auxin will fall south, and elongate these cells. this elongation of cells then forces the stem of the seed upwards.
the same theory is with the roots, yet im pretty sure another hormone that i cant remember the name for, elongates the upper cells of the root, therefore root cells grow downwards.
2007-03-17 21:07:31 · answer #1 · answered by Anonymous · 0⤊ 0⤋
The first part of a new plant that breaks the seed coat is a tiny, delicate embryonic root.This root will grow straight down into the soil. Although chemical and hormonal actions/reactions are occurring during this stage of plant life, it is the force of gravity that pushes the root downward. It don't matter which way the seed is planted,the root will always grow down and the stem and leaves will grow straight up towards the surface.
2007-03-18 08:13:16 · answer #2 · answered by gardeningfool42 4 · 1⤊ 0⤋
If they didn't instinctively "know" which way to go the species wouldn't survive. You can say throgh evolution and natural selection the species that could find the right way survived. So it is in their genes!
2007-03-18 10:12:16 · answer #3 · answered by Gone fishin' 7 · 0⤊ 0⤋
Always the seedlings creep towards the sunlight this is called phototrophism.
2007-03-18 20:50:31 · answer #4 · answered by moosa 5 · 0⤊ 0⤋
They'll always know where air is because they always grow towards sunlight. It's the way nature works.
2007-03-18 03:59:44 · answer #5 · answered by B.lyd 1 · 0⤊ 1⤋
That is God's most complex miracle, my friend.
2007-03-18 03:58:00 · answer #6 · answered by Anonymous · 0⤊ 0⤋
they can sense the air....n crawl towards it...
2007-03-18 09:55:15 · answer #7 · answered by Anonymous · 0⤊ 0⤋