A Bubble Siphon
Ali and Nellie decided to show how the
water is transported in plants. They knew that the water absorbed by the
roots go up through the xylem vessels come down through the phloem
vessels. So they made a cut-out of a tree in plywood,
Fig. 1. The Initial stage of the exhibit.
They agreed to run the water using the siphon method. This is the method
used to empty fish tanks. You fill a saline tube with water, insert one
end to the fish tank and keep the other end below the water level. The
water will go up the tube and come down. Unfortunately when they tried
it out they could not see the water flowing inside the tube.
Then Nellie came out with a wonderful idea. “Make a hole in the
ascending tube”. They tried this out in their aquarium. In the tube they
made an incision (a hole). It worked. Silvery bubbles appeared to go up
the tube and down they came. Ali and Nellie screamed, laughed and they
called their parents to see the bubbles. They painted the reverse side
of the ascending column red, to represent the xylem tubes and the other
side they painted blue, to represent the phloem tissue.
It was highly commended by the teachers and the visitors to the fair.
Just to enjoy this experiment you don’t need plywood cut-outs and fish
tanks. What you need is a basin of water and a saline tube. Dip one end
of the tube into the water and suck through the other end. Keep the free
end below the water level and let the water flow out. An opening can be
made with a nail at a place marked by the arrow (look below).
Another option would be to show the blood circulation in the arteries
and veins by using this method.