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

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.

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 (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.

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