Carbon Transfer Through Snails and Elodea – Virtual Lab



Name:_________________________________ Date:______________

Carbon Transfer Through Snails and Elodea – Virtual Lab

Directions to Virtual Lab

From the Internet: Go to Ms. Evans webpage on the RV website.

Click “Links” (upper left-hand corner) – this should take you to virtual biology

labs.

Select “Carbon Transfer Through Snails and Elodea” from the list of labs.

Background:

All organisms are dependent on a healthy carbon dioxide-oxygen balance. Photosynthesis and cellular respiration are key processes in maintaining this balance. Plants (through the process of photosynthesis) use energy absorbed from sunlight, water, and carbon dioxide to produce carbohydrates and oxygen. Animals and plants, through the process of cellular respiration, use oxygen and sugars to produce carbon dioxide, water, and energy needed to maintain life.

In this investigation, you will use snails and Elodea to explore a biological system.

Purpose:

To determine how carbon dioxide cycles through a biological system.

Materials:

Get from the Checklist on the Explore part of the virtual lab

- Select each item in the lab. Read the description that appears for each item. Once you have selected all the items (8 total), click procedure to start the lab.

Procedure:

Follow the steps to the lab given on the screen until you complete all seven (7) steps.

Hypothesis:

Explain how carbon dioxide cycles in the aquarium water through snails and Elodea.

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Set up your experiment in the following manner:

- Dependent Variable: The level of CO2 in the test tube

- Operational definition: I will measure the level of CO2 by: observing the color of the solution.

- Independent Variable: the amount of light

- Control: Test tube with no snails and no Elodea plants

- You will use 8 test tubes in this set up.

Set up the test tubes in the following way:

Test Tube 1: only Bromthymol Blue (BTB) Solution

Test Tube 2: BTB, 0 snail, 1 Elodea Plant

Test Tube 3: BTB, 1 snail, 0 Elodea Plant

Test Tube 4: BTB, 1 snail, 1 Elodea Plant

Place one test tube rack under the grow light. Place the other test tube rack under the test tube rack cover.

Data/Results:

TEST TUBES IN THE DARK

|Test Tube |Contents |Starting Color |Predicted End Color |End Color |

|1 |Only BTB solution |green | | |

|2 |BTB, 0 snails; 1 Elodea plant |green | | |

|3 |BTB, 1 snail, 0 Elodea Plant |green | | |

|4 |BTB, 1 snail, 1 Elodea Plant |green | | |

TEST TUBES IN THE LIGHT

|Test Tube |Contents |Starting Color |Predicted End Color |End Color |

|1 |Only BTB solution |green | | |

|2 |BTB, 0 snails; 1 Elodea plant |green | | |

|3 |BTB, 1 snail, 0 Elodea Plant |green | | |

|4 |BTB, 1 snail, 1 Elodea Plant |green | | |

Discussion:

1) Conclude. What is the relationship between snails and Elodea?

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2) Analyze. Why did the color of the Bromthymol Blue (BTB) solution change?

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3) Analyze. What was the importance of a control in your experiment? What would you conclude if

the color of the solution in the control changed?

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4) Infer. When you began the experiment, was there CO2 in the water? In the test tubes that contained Elodea, where did the CO2 go?

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5) Infer. Which gas did the snails release? What observation supports this inference?

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6) Apply. Based on the results of your experiment, explain why you need to add the Elodea to your snail aquarium.

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Conclusion: Write a paragraph to summarize how the processes of cellular respiration and photosynthesis are dependent on each other.

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