April 13, 2011
BKW fourth graders recently
got to spend some time experimenting with visiting scientist Matt Chase.
The students performed experiments to see if yeast could use different kinds of sugar as food.
"We tested sucrose, glucose and fructose," Chase said.
The students were given a yeast solution, a sugar solution and water, and an instruction sheet. They added yeast and different amounts of sugar solution and water to tubes. They also made a tube with 10 ml of water as a control . The tops of the tubes have tiny holes. They bundled the tubes together, and inverted them into a container of warm water.
"We let the yeast 'eat'“ for 15 minutes, and during that time, we talked about the yeast using sugar and making gas," Chase said. "The tubes would trap the gas, and we would measure how much gas they made by seeing how much of the liquid was squeezed out of the tubes. We talked about what would happen if the yeast could not eat the sugar, and we predicted what would happen in the tubes with different amounts of sugar."
After 15 minutes, the students the tubes back over and measured the amount of liquid left. They recorded their measurements, and then for each tube, subtract that volume from the control.
"I also gave them a graph sheet set up for them to graph their results, which they really seemed to enjoy doing," Chase said.
In this picture Jake
Valechovic exhales through a straw after exercising for one
minute resulting in increased respiration. The indicator solution he is
blowing into measures carbon dioxide as an acid (carbonic acid) which
turns the solution from blue to yellow. Meanwhile, we had yeast cells
respiring nearby as they converted glucose into carbon dioxide. The
yeast respiration was measured using tubing into the same indicator
solution.
District HOME
