1. General Biology Laboratory Notes
Snail & Elodea Lab
General Biology
Laboratory Notes

2. Introduction Plant = Producer Snail = Consumer
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.

3. Photosynthesis
Carbon Dioxide + Water + Sun’s Energy → Food + Energy

4. Respiration Occurs in plants and animals.
Plants respire as they grow, circulate nutrients, and utilize energy.

5. 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.

6. Demonstration Blow into a straw that is immersed in water and BTB.
1) Do you see a color change?
2) If so, why?

7. Why did the water change color?
Carbon dioxide (CO2) forms an acid when dissolved in water:
H20 + CO2 ↔ H2CO3 (Carbonic Acid)
In this experiment, bromthymol blue can be used to indicate, indirectly, the presence of CO2 and the dominance of respiration.
Lab Set-Up.

8. 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: A1, A2, A3, A4: Light 1st Night
Tubes: B1, B2, B3, B4: Dark 1st Night