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 (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