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foudn this:
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Did you ever wonder how plants know to grow with their leaves climbing up towards the sky and their roots pushing down into the soil? What would happen if you put a plant in soil upside down?[/FONT]
[FONT=Verdana,Arial,Times New I2]Here is an experiment to test what will happen.[/FONT]
[FONT=Verdana,Arial,Times New I2]You need: ten radish or bean seeds, 2 jam jars, blotting paper, paper towels, string, tap water.[/FONT]
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Soak 8 seeds in water overnight. Line the inside of your jars with blotting paper that you or your parents have cut to fit. Fill the middle of each jar with crumpled paper towel. Saturate the blotting paper and the paper towel with water and pour off any extra water that didn't soak in. Be sure to keep the paper moist or your seeds will not grow. Put four soaked seeds between the glass and the blotting paper at the top of each jar. (you don't have to feed the seeds because they already contain food) Place the seeds in all different positions - horizontal, vertical and diagonal.[/FONT]
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After they have grown 2.5 cm above the top of the jars, set one jar on its side. Have a look at your sideways plant a few days later. Are the stems growing upwards? They should be.[/FONT]
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Stems and leaves grow in the direction of light and away from the force of gravity. This is called negative geotropism because the plant is growing away from the force of gravity.[/FONT]
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Can you think of an example of positive geotropism? What about the roots of the plant? They are growing towards the force of gravity. How does it work? Plants have hormones that respond to the pull of gravity and tell the plant which way to build cells and grow. So now you know that you can't plant a seed upside down.[/FONT]