Snail & Elodea Lab

1. Snail & Elodea Lab General Biology Laboratory Notes

2. 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.

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