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Ecosystems

Investigation 3 – Lab

 

 

 

 

 

 

 

MINDSET

This Investigation is designed to:

  • reinforce for you the connection between energy transfer and biomass transfer between the levels of an ecosystem,
  • demonstrate to you that the amount of biomass available at the producer level of an ecosystem determines the amount of biomass in each successive level of the ecosystem,
  • demonstrate that the amount of biomass in a given level of an ecosystem determines the number of animals in that level, and
  • demonstrate that the amount of biomass available at the producer level of an ecosystem determines the number of levels in an ecosystem.

 

BE PREPARED

Student Preparation for the Investigation includes gathering the following materials.

Note: The materials are listed in students’ SDRs. They are also listed below for your reference.

  • (1) meter stick
  • (1) metric ruler
  • (2) plastic straws
  • (1) 400 ml beaker containing 300 ml of pinto beans
  • (1) 400 ml beaker containing 100 ml of pinto beans
  • (4) 50 ml beakers
  • (1) weigh dish
  • (1) triple beam balance

Note: Your group will also need approximately seventy (70) gram cubes, twenty (20) small bears, ten (10) medium bears, and five (5) large bears to complete each ecosystem model. These may be distributed prior to the start of the Investigation or you may opt to obtain these items after determining the number needed for the first ecosystem.

Direct one student from each lab group to collect the materials listed in their SDRs.

INVESTIGATE

  • During this Investigation, you will investigate how the amount of energy captured by the biomass of producers influences the number of animals and levels that can exist in an ecosystem.
    • You will be exploring and evaluating two ecosystems in the same way that ecologists study ecosystems.
    • Reflect on the PreLab video as you move through the procedural steps.
    • During the Experiment, every procedural step is important. If one step is skipped, data can become invalid. To help you keep on track, read each step thoroughly, complete the step, then check it off (Read it – Do it – Check it).
    • Complete all of the procedural steps in your SDR.
  • Note: The procedural steps are listed below for your reference. Teacher “Notes” are inserted, as needed, to help facilitate the lab.

 

  • The Experiment includes the following:

1. Label the four (4) 50 ml beakers “A”, “B”, “C”, and “D”.

2. Label the beaker containing 300 ml of beans “Ecosystem ML300”. Label the beaker containing 100 ml of beans “Ecosystem ML100”.

3. Construct the first ecosystem- Ecosystem ML300:Eco 3 Lab 1st

A. Place two (2) 60 cm pieces of masking tape 100 cm apart on the table.

B. Place a mark 5 cm from each end of each piece of tape.

C. Connect the marks on the two pieces of tape with two (2) 100 cm pieces of masking tape.

4. Ecologists use a square frame to define the area to sample. Construct a square sampling frame as follows:Eco 3 Lab 2nd

A. Measure the length of two (2) plastic straws.

B. Mark the halfway point of each straw and cut the straws in half.

C. Cut four (4) 5 cm pieces of masking tape.

D. Place one end of a straw half on a piece of tape.

E. Place a second straw half at right angles to the first half so that the end of the second half is against the side of the first. Fold the tape securely around the ends.

F. Place the other end of the second straw half on another piece of tape.

G. Place a third straw half at right angles to the second half and fold the tape securely around the ends, keeping the sides of the frame as flat as possible.

H. Place the other end of the third straw half on another piece of tape.

I. Place a fourth straw half at right angles to the third half and fold the tape securely around the ends, again keeping the sides of the frame as flat as possible.

J. Arrange the free ends of the first and fourth halves on the final Eco 3 Lab 3rdpiece of tape so that the end of the first half is against the side of the fourth half. Fold the tape securely around the ends.

K. If necessary, snip the tape on the inside corners and press it flat against the sides of the frame to make the corners clean.

    • Trial 1:
      1. Pour the beans representing the plant biomass ofEco 3 Lab Trial 1 Ecosystem ML300 into the taped-off area of the lab table. Spread the beans as evenly as possible within the taped edges.
      2. Obtain 4 biomass samples from the ecosystem as follows:

    A. Randomly place the sampling frame into an area of the ecosystem.

    B. Collect the beans inside the sampling frame. Eco 3 Lab Trial 1 BDo not collect any beans covered by the sampling frame (see arrows).

    C. Place the beans in beaker “A.”

    D. Randomly place the frame into an unsampled area of the ecosystem.

    E. Collect the beans inside the frame and place them in beaker “B.”

    F. Randomly place the frame into another unsampled area of the ecosystem.

    G. Collect all the beans and place them in beaker “C.”

    H. Randomly place the frame into a fourth unsampled area and place all the beans in beaker “D.”

    I. Collect the beans inside the frame.

    3. Determine the biomass in grams of each sample of beans using the triple beam balance. Refer to the Procedures, Triple Beam Balance Equilibration, Triple Beam Balance Use and Operation, and Measuring Mass Using a Weigh Dish or Beaker if necessary.

    4. Record the masses in Table A of the Student Data Record.

    5. Calculate the total and average biomass of the samples.

    6. Return all of the beans to the “Ecosystem ML300” beaker.

    7. Calculate the average amount of plant biomass in the ecosystem. To do this, the area of Ecosystem ML300 and the area of the sampling frame must first be calculated.

    8. Calculate the area of Ecosystem ML 300 in square meters.

    A. To find the area, first measure the length of the ecosystem by measuring the distance between the left and right pieces of tape.

    B. Record: Write the length of the ecosystem in Table B at the end of the Student Data Record.

    C. Next find the width of the ecosystem by measuring the distance between the top and bottom pieces of tape.

    D. Record: Write the width of the ecosystem in Table B.

    E. Convert the measurements to meters by dividing each measurement by 100. Record the converted measurements in Table B.

    F. Calculate: Find the area of the ecosystem in meters by multiplying the length of the ecosystem by the width. Use the formula below

      1. Area = Length x Width

      G. What is the area of Ecosystem ML300? Student answers may vary. Sample data is shown below.

      • Area: 0.48m x 1m = 0.48m2

        Note: Students may assume that the area of the ecosystem is 0.60 m x 1 m because the two of the pieces of tape cut were 60 cm in length. However, when constructing the ecosystem, they were to move inward 5 cm on each side. Therefore, the area INSIDE the ecosystem is at most 0.50 m x 1 m.

      9. Calculate the area of the sampling frame in square meters.

      A. To find the area, first measure the length of the sampling frame in centimeters. Record the length in Table C at the end of the Student Data Record.

      B. Measure the width of the sampling frame in centimeters. Record the width in Table C.

      C. Convert the measurements from centimeters to meters.

      D. Calculate the area of the sampling frame below. Use the formula below. Student answers may vary. Sample data is shown below.

        1. Area = Length x Width

          Area = 0 .09 m  x 0.09 m = o.0081 m2

        10. Calculate the average amount of plant biomass in Ecosystem ML 300:

        A. First, find the average amount of plant biomass per meter. To do this, divide the average biomass of the samples by the area of the sampling frame. Student answers may vary. Sample data is shown below.

          1. Eco 3 Lab Trial 1 C

            Average biomass per meter = 5.75g/0.0081 m2 = 710 g/m2

            B. Next, find the average amount of plant biomass in the ecosystem. To do this multiply the average amount of plant biomass per meter by the total area of the ecosystem. Student answers may vary. Sample data is shown below.

                Average plant biomass = Average biomass per meter x Area of ecosystem

                Average plant biomass = 710 g/m2 x 0.48 m2 = 340.8 g

                C. Record: Write the average amount of plant biomass in Ecosystem ML 300 in Table A of the Student Data Record.

                 

                • Tool: Prediction
                • Use the Prediction tool to answer the following question:
                  • How many levels of the ecosystem can the plant biomass of Ecosystem ML 300 support?  
                1. In Ecosystem ML 300 there are herbivores and three types of carnivores- Carnivore A, Carnivore B, and Carnivore C. Table D on the last page of the Student Data Record shows each consumer in Ecosystem ML 300, the biomass of each consumer, and the biomass needed by each herbivore and carnivore in order to survive.
                2. Begin to build the levels that can be supported by the plant biomass in Ecosystem ML 300. Place the beaker of beans with the total amount of plant biomass in the center of the table.
                3. Look back at Table A. What is the amount of plant biomass in Ecosystem ML 300?

                  14. If each herbivore requires 5 g of plant biomass to survive, how many herbivores can Ecosystem ML300 support? Use the space below to write your calculations. Record the number of Herbivores in Table E.

                  15. Place the appropriate number of Herbivores (gram cubes) next to the beaker of Plants.

                  16. Calculate: Use the information in Table D of the Student Data Record to calculate the number of animals that can live in each level of Ecosystem ML 300.

                  A. Determine the number of Carnivore A that can be supported by the Herbivores. Record your answer in Table E.

                  • Eco 3 Lab Trial 1 D

                  B. Place the appropriate number of Carnivore A next to Herbivores.

                  C. Determine the number of Carnivore B that can be supported by the Carnivore A. Record your answer in Table E.

                    D. Place the appropriate number of Carnivore B next to the Carnivore A.

                    E. Determine the number of Carnivore C that can be supported by the Carnivore B. Record your answer in Table E on of the Student Data Record.

                      F. Place the appropriate number of Carnivore B next to the Carnivore C.

                          1. What do you notice about the biomass in each level of Ecosystem ML300 as you move up in the ecosystem? 
                          1. What do you notice about the number of animals in each level of Ecosystem ML300 as you move up in the ecosystem? 

                         

                        • Trial 2:
                          1. Spread the contents of the “Ecosystem ML100” beaker evenly inside the boundaries of the ecosystem.
                          2. Obtain four (4) samples of plant biomass from the ecosystem using the same procedure with the sampling ring as for Ecosystem ML 300. Record their masses in Table A of the Student Data Record. Calculate the average amount of plant biomass of the four samples.
                          3. Transfer the area of the ecosystem from Table B and the area of the sampling frame from Table C.

                            1. Calculate the average amount of plant biomass in Ecosystem ML 100:

                          A. First, find the average amount of plant biomass per meter. To do this, divide the average biomass of the samples by the area of the sampling frame.

                            B. Next, find the average amount of plant biomass in the ecosystem. To do this multiply the average amount of plant biomass per meter by the total area of the ecosystem.

                              C. Record: Write the average amount of plant biomass in Ecosystem ML 100 in Table A of the Student Data Record.

                                  1. Use the information in Table D to determine the biomass of each consumer and the biomass needed by each herbivore and carnivore in order to survive.
                                  2. Begin to build the levels that can be supported by the plant biomass in Ecosystem ML 100. Place the beaker of beans with the total amount of plant biomass in the center of the table.
                                  3. Look at Table A. What is the amount of plant biomass in Ecosystem ML 100?
                                  1. If each herbivore requires 5 g of plant biomass to survive, how many herbivores can Ecosystem ML100 support? 
                                    1. Place the appropriate number of Herbivores next to the beaker of Plants.
                                    2. Calculate: Use the information in Table D to calculate the number of animals that can live in each level of Ecosystem ML 100.

                                  A. Determine the number of Carnivore A that can be supported by the Herbivores. Record your answer in Table E.

                                    1.  

                                      B. Place the appropriate number of Carnivore A next to the Herbivores.

                                      C. Determine the number of Carnivore B that can be supported by the Carnivore A. Record your answer in Table E.

                                        D. Place the appropriate number of Carnivore B next to the Carnivore A.

                                        E. Determine the number of Carnivore C that can be supported by the Carnivore B. Record your answer in Table E.

                                          F. Place the appropriate number of Carnivore C next to the Carnivore B.

                                              1. What do you notice about the biomass in each level of Ecosystem ML100 as you move up in the ecosystem? 

                                            12. What do you notice about the number of animals in each level of Ecosystem ML100 as you move up in the ecosystem? 

                                             

                                            CLEAN UP

                                            Let students know your expectations for clean up. Ask them to clean up.