Engineering Digital Biodegraders for Biological Cleanup

Learning Objectives

After this activity, students should be able to:

• Explain how the process of natural selection leads to organisms that are well suited for the environment.
• Discuss characteristics of the environment and organisms that influence the process of natural selection.
• Develop and test a hypothesis and then use the data to draw conclusions.
• Propose a protocol for critiquing proposed solutions to the problem.

NGSS Alignment

Performance Expectations

• HS-ETS1-4. Use a computer simulation to model the impact of proposed solutions to a complex real-world problem with numerous criteria and constraints on interactions within and between systems relevant to the problem.
• HS-LS4-4. Construct an explanation based on evidence for how natural selection leads to adaptation of populations.

Science & Engineering Practices

• Use mathematical models and/or computer simulations to predict the effects of a design solution on systems and/or the interactions between systems.
• Construct an explanation based on valid and reliable evidence obtained from a variety of sources (including students' own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.

Disciplinary Core Ideas

• Both physical models and computers can be used in various ways to aid in the engineering design process. Computers are useful for a variety of purposes, such as running simulations to test different ways of solving a problem or to see which one is most efficient or economical; and in making a persuasive presentation to a client about how a given design will meet his or her needs.
• Natural selection leads to adaptation, that is, to a population dominated by organisms that are anatomically, behaviorally, and physiologically well suited to survive and reproduce in a specific environment. That is, the differential survival and reproduction of organisms in a population that have an advantageous heritable trait leads to an increase in the proportion of individuals in future generations that have the trait and to a decrease in the proportion of individuals that do not.

Crosscutting Concepts

• Models (e.g., physical, mathematical, computer models) can be used to simulate systems and interactions—including energy, matter, and information flows—within and between systems at different scales.
• Empirical evidence is required to differentiate between cause and correlation and make claims about specific causes and effects.
• Scientific knowledge is based on the assumption that natural laws operate today as they did in the past and they will continue to do so in the future.

Materials List

Each group needs:

• computer with the Avida-ED software, freely available at https://avida-ed.msu.edu/app/AvidaED.html
• paper/lab notebook and pencil (or computer and word processing software), for writing answers to questions
• Evolving TCE Biodegraders Handout, one per student

Introduction/Motivation

Your school administrators want to buy an adjacent piece of property to build new athletic facilities. The property includes a large warehouse that has been used for various industrial purposes over the last 50 years. During the site inspection it was learned that the soil and water around the warehouse are contaminated by trichloroethylene (TCE), a hazardous chemical used as a spot remover in dry cleaning and as a degreaser for metal parts. The school board has asked our class to team up with an environmental consulting company to help cleanup the TCE so that our school can move ahead with purchasing and using the land.

(Continue by having students read aloud the complete hypothetical design challenge scenario as provided in the attached Evolving TCE Biodegraders Handout.)

Pre-Req Knowledge

A basic understanding of evolution by natural selection is required. This activity should be introduced only after completing the introductory Evolution of Digital Evolution lesson and the Studying Evolution with Digital Organisms activity.

Procedure

Before the Activity

• Teacher to review the activities on in advance so that s/he can help direct students during class.
• Prepare enough computers with Avida-ED installed for each pair of students.
• Make copies of the Evolving TCE Biodegraders Handout, one per person. This handout provides the scenario, background information, and questions to guide students' experimental designs.

With the Students

1. With student pairs each at computers that have Avida-ED installed, give each student a handout.
2. As a class, read aloud the hypothetical design challenge scenario.
3. Facilitate a class discussion to explore what students know about the problem and what they need to know about the problem.
4. Read aloud the background information and the experimental design questions. Clarify any language in the questions so that the task is clearly defined—without providing any suggestions for how to solve the problem.
5. Have students complete the experimental design questions, writing out their answers. Through this process, students:
   • develop hypotheses and predictions using the "if... then..." format
   • determine how much data to collect
   • write concise descriptions of their experimental design methods (including settings, replications, data collection, etc.) that are clear enough for replication by others
   • identify dependent and independent variables and the controls
   • organize their data into tables
   • determine the graph(s) for best data presentation

6. Note: Students may choose to change one or more of the organism or environmental variables in order to influence the evolution of the "oro" function in the population. Students' protocols may go in a number of directions including changing only one variable at a time, changing multiple variables, evolving the "oro" function as quickly as possible using one set of parameters and then transplanting that organism to another environment to "clone" it, or using only one static set of parameters for the population. Permit students to pursue any of these options; as a group, discuss the pros and cons of each.
7. Next, students collect data, documenting the parameters for each run and recording observations.
8. Then students create graphs to display their results.
9. Next, students describe how their results support/refute their hypotheses.
10. Then students propose protocols for evolving bacteria to degrade TCE, including preparing short class presentations to explain their proposals.
11. As a class, watch and listen to the group proposals.
12. Facilitate a class discussion to determine which group proposal most effectively evolves efficient TCE degrading bacteria. Encourage students to critique the proposed protocols and come to a consensus about what should be presented to the environmental consulting company and why. Are there any unanswered questions? Do we feel confident submitting one of these proposals? Do we need to run more experiments? This should lead to a rich discussion about the nature of scientific inquiry and the engineering design process.

Vocabulary/Definitions

Avida-ED: An educational version of the digital evolution software, Avida. Avida-ED is an award-winning educational application developed for undergraduate biology courses to help students learn about evolution and the scientific method by enabling them to design and perform experiments to test hypotheses about evolutionary mechanisms using evolving digital organisms. evolution: The change in the genetic composition of a population from generation to generation. natural selection: A process in which organisms with certain inherited characteristics are more likely to survive and reproduce than are organisms with other characteristics; the main driving force of evolution.

Assessment

Activity Embedded Assessment

Handout Questions: Collect students' answers to the handout questions and/or the student-generated data and analysis as a source of formative assessment.

Data Summary Presentation: Grade the groups' oral class presentations, evaluating for subject matter comprehension, concise description of experimental design methodology, convincing presentation of proposed protocol to meet the design challenge, and overall clarity of communication. Alternatively, instead of oral presentations, have students create posters or other visual representations of the data.

Copyright

2013 by Regents of the University of Colorado; original © 2011 Michigan State University

Contributors

Wendy Johnson, Amy Lark, Robert Pennock, Louise Mead

Supporting Program

Bio-Inspired Technology and Systems (BITS) RET, College of Engineering, Michigan State University

Acknowledgements

The contents of this digital library curriculum were developed through the Bio-Inspired Technology and Systems (BITS) RET program under National Science Foundation RET grant no EEG 0908810. However, these contents do not necessarily represent the policies of the NSF and you should not assume endorsement by the federal government.