Carbon Transfer through Snails and Elodea – Virtual Lab



Carbon Transfer through Snails and Elodea – Virtual Lab

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Directions to Virtual Lab – Use the link on my homepage to Virtual Photosynthesis and Respiration Lab ()

❖ Select Carbon Transfer Through Snails and Elodea

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.

Problem 1: Do plant do respiration, photosynthesis or both?

Materials: See 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, click procedure to start the lab.

Hypothesis: The Elodea plant will do ______________ (photosynthesis/respiration) when left in the ____________ (light/dark ) and will do _______________ (photosynthesis/respiration) when left in the ____________ (light/dark ).

Set up your experiment in the following manner:

You will use 4 test tubes in this set-up. Set-up the test tubes in the following way:

Rack 1 – place in the dark

➢ Test tube 1: only Bromthymol Blue (BTB) solution

➢ Test tube 2: 1 Elodea plant

Rack 2 – place in the light

➢ Test tube 1: only Bromthymol Blue (BTB) solution

➢ Test tube 2: 1 Elodea plant

|Test Tube |Starting Color |Predicted End Color |Actual End Color |

|Dark: only Bromthymol Blue (BTB) | | | |

|solution | | | |

|Dark | | | |

|1 Elodea plant | | | |

| | | | |

|Light | | | |

|only Bromthymol Blue (BTB) solution| | | |

| | | | |

|Light | | | |

|1 Elodea plant | | | |

| | | | |

Add stoppers

Place the test tube under the grow light and under the rack cover.

Click Start.

Record the final results in the table above

Analysis:

1. What happened when the elodea was keep in the dark? Did the color change? Why or why not?

2. What happened when the elodea was left in the light? W Did the color change? Why or why not?

When asked if you want to start a new experiment or continue to analyze your results- CHOOSE NEW!!

Problem 2:

You are setting up a snail aquarium at home. Your aquarium kit contains a bag of snail eggs on an Elodea plant. The instructions say to pour the content, including the Elodea, into the aquarium, but you are not sure why you need to Elodea. Why might Elodea plants be helpful in maintaining a health ecosystem?

Purpose: To determine how carbon dioxide cycles through a biological system.

Procedure: Follow the steps to the lab given on the screen.

Hypothesis: If there is ______________ (Elodea/snail) then it will release ____________ (O2 / CO2 ) and the _______________ (Elodea/snail) will take it in.

Set up your experiment in the following manner:

Dependent variable: Amount of carbon dioxide present

Operation Definition: Color of the solution

Independent variable: number of snails

Control: only Bromthymol Blue (BTB) solution

You will use 4 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: 0 snails, 1 Elodea plant

➢ Test tube 3: 1 snail, 1 Elodea plant

➢ Test tube 4: 2 snails, 1 Elodea plant

|Test Tube |Starting Color |Predicted End Color |Actual End Color |

|only Bromthymol Blue (BTB) solution| | | |

|0 snails, 1 Elodea plant | | | |

| | | | |

|1 snail, 1 Elodea plant | | | |

| | | | |

|2 snails, 1 Elodea plant | | | |

| | | | |

Add stoppers

Place the test tube under the grow light

Analysis and Conclusion:

1. What is the relationship between snails and Elodea

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

3. What was the importance of a control in your experiment?

What would you conclude if the color of the solution in the control changed?

4. When you began the experiment, was there CO2 in the water?

In the test tubes that contained Elodea, where did the CO2 go?

5. Which gas did the snails release?

What observations support this?

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

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