Transformations in Matter and Energy Carbon TIME is an NSF-funded partnership led by Michigan State University
Activity 5.2 - 5.2: Molecular Models for Cows Growing: Digestion and Biosynthesis (40 min)

Target Student Performance
Students use molecular models to explain how polymers are broken into monomers during the process of digestion and monomers are linked into polymers during biosynthesis.
Note: This is a 2-turtle lesson, which is appropriate for advanced middle school or high school students and classes. If you decide not to teach this lesson, you can move directly from 5.1 to 5.3
Resources You Provide
- scissors (1 per pair of students)
- removable or re-stick tape (1 dispenser per pair of students)
Resources Provided
- 5.2 Molecular Models for Cows Growing: Digestion and Biosynthesis PPT
- 5.2 Polymers for Cutting Handout (1 copy for every four students)
Recurring Resources
- Molecular Models 11 x 17 Placemat (1 per pair of students)
- Forms of Energy Cards (1 per pair of students)
- Digestion and Biosynthesis of Carbohydrates 11 x 17 Poster
- Digestion and Biosynthesis of Fat 11 x 17 Poster
- Digestion and Biosynthesis of Protein 11 x 17 Poster
- Cow 11 x 17 Poster
Setup
Prepare one Molecular Models 11 x 17 Placemat, one pair of scissors, one set of Forms of Energy Cards, and one removable tape dispenser for each pair of students. Print one copy of 5.2 Polymers for Cutting Handout for every four students. Cut each handout in half so you can give each pair one of each polymer (protein, carbohydrate, and fat) and the attached water molecules. Prepare a computer and a projector to display the PPT. Print and hang the Digestion and Biosynthesis 11 X 17 Posters, the Cow 11 x 17 Poster, and the Metabolic Pathways 11 x 17 Poster.
Assessment
- Matter tracing: note if students are able to recognize that the same atoms that were in the reactants are also in the products.
- Energy tracing: note the ways that students explain how chemical energy is conserved through both digestion and biosynthesis.
Tips
- This activity may not be appropriate for middle school students due to its emphasis on molecular details of digestion and biosynthesis.
- Laminate the Molecular Models 11 x 17 Placemat. These will be used multiple times in each unit.
- During the molecular modeling activity and animation, focus on how matter and energy are conserved through the chemical change. This is the main goal of the activity!