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Snail & Elodea Lab General Biology Laboratory Notes
Introduction Plant = Producer – Can utilize light to make food as it grows. Snail = Consumer – Cannot manufacture its own food. – Must consume organic compounds produced by plants and/or other animals.
Photosynthesis Carbon Dioxide + Water + Sun’s Energy → Food + Energy
Respiration Occurs in plants and animals. Plants respire as they grow, circulate nutrients, and utilize energy.
Indicator A substance that shows the presence of a chemical substance by changing color. Bromthymol Blue, (BTB): Indicator that changes to a green or yellow color in the presence of an acid.
Demonstration Blow into a straw that is immersed in water and BTB. 1) Do you see a color change? 2) If so, why?
Why did the water change color? Carbon dioxide (CO 2) forms an acid when dissolved in water: – H 20 + CO 2 ↔ H 2 CO 3 (Carbonic Acid) In this experiment, bromthymol blue can be used to indicate, indirectly, the presence of CO 2 and the dominance of respiration. Lab Set-Up.
Lab Observations Take down observations of each tube for the starting day on your observation sheet. Then, on a sheet of paper titled “Snail & Elodea Lab, ” write your hypothesis about what will happen to each tube during this experiment. Tubes: A 1, A 2, A 3, A 4: Light 1 st Night Tubes: B 1, B 2, B 3, B 4: Dark 1 st Night