1. Animals Unit Activity 5.4: Explaining How Cows Grow: Biosynthesis
Carbon: Transformations in Matter and Energy
Environmental Literacy Project Michigan State University
Animals Unit Activity 5.4: Explaining How Cows Grow: Biosynthesis
(Optional) Have students read about digestion and complete part of the graphic organizer.
Pass out 5.4 How do Animals Grow? Reading. Higher level students may not need the review of content provided in this reading, but you may want them to add to the graphic organizer started in Activity 4.2.
The reading provides a summary explanation of biosynthesis and additional information about of metabolic pathways (students can refer to the Metabolic Pathways 11 x 17 Poster to see some of the other pathways).
Students can complete the reading individually or in pairs.
After reading, students can complete the biosynthesis section of the Matter and Energy in Animals Graphic Organizer that they started completing in Activity 4.2.
Have students connect their atomic-molecular explanations to the macroscopic scale by referring to the cow poster.
Show slide 16. Have students look at the Cow 11 x 17 Poster and discuss with a partner the parts of a cow involved in digestion and biosynthesis on a macroscopic scale.
Tell students that all parts (all cells) of a cow’s body undergo biosynthesis.

2. Unit Map
You are here
Use the instructional model to show students where they are in the course of the unit.
Show slide 2 of the 5.4 Explaining How Cows Grow: Biosynthesis PPT.

3. Revisit your arguments
Think about what you know now that you didn’t know before. What have you learned?
Remind students of their unanswered questions.
Using slide 3 of the PPT have students revisit their arguments and unanswered questions from the Mealworm Investigation by looking at 3.3 Evidence-Based Arguments for Mealworms Eating.
Remind students that after explaining cellular respiration in Lesson 4.2 and digestion in Lesson 5.3, there were still unanswered questions about how animals grow.
In today’s lesson, students will use what they learned in Lesson 5.1 (and 5.2) to explain how cows use food for growth.

4. How do animals use food as materials for growth?
Image Credit: Craig Douglas, Michigan State University
Discuss what happens to the small organic molecules after digestion.
Show slide 4-5 of the PPT. Remind students that the products of digestion (small organic molecules or monomers) can be used by cells for either growth or energy.
Allow students to explain the processes of digestion and cellular respiration as a review.

5. Step 2: Biosynthesis Materials for growth: Biosynthesis Food Digestion
Energy: Cellular respiration
Image Credit: Craig Douglas, Michigan State University
Discuss what happens to the small organic molecules after digestion.
Show slide 4-5 of the PPT. Remind students that the products of digestion (small organic molecules or monomers) can be used by cells for either growth or energy.
Allow students to explain the processes of digestion and cellular respiration as a review.

6. Constructing explanations
Consider the following as you construct your explanation:
Evidence from the investigation
What you learned from the molecular modeling or tracing activity
Three Questions Handout
Have students complete their Explanations Process Tool for Biosynthesis.
Show slide 6 of the 5.4 Explaining How Cows Grow: Biosynthesis PPT. Give each student one copy of 5.4 Explanations Tool for Cow Biosynthesis.
Tell students that in this part of the investigation, they will combine everything they learned about how cows use food to grow into an explanation.
Remind them to consider both their evidence from the investigation as well as what they learned in the molecular modeling (or tracing) activity to construct their explanations.
Give students about 10 minutes to complete the Explanations process tool.

7. Comparing Ideas with a Partner
Compare your explanations for each of the Three Questions.
How are they alike?
How are they different?
Check your explanation with the middle- and right-hand columns of the Three Questions handout.
Consider making revisions to your explanation based on your conversation with your partner.
Have students share explanations with each other.
Show slide 7 of the 5.4 Explaining How Cows Grow: Digestion and Biosynthesis PPT. Divide students into pairs and have them compare explanations for the Three Questions and the final explanation on the process tool.
Have students use the Three Questions 11 x 17 Poster (or Handout) as a reference. Have students check their explanations with the middle and right-hand columns of the poster or handout to make sure they are following the “rules.”

8. The Matter Movement Question
Small organic molecules (monomers: amino acids, glucose, fatty acids, glycerol)
Large organic molecules (polymers: proteins, carbs, fats)
Image Credit: Craig Douglas, Michigan State University
Have students think about how biosynthesis answers the Matter Movement question.
Use slides 8-10 in the PPT to have the students discuss what is happening to matter during biosynthesis and to have them check their answers to the Matter Movement Question on their 5.4 Explanations Tool for Cow Biosynthesis.
Show students slide 8 to have them think about where atoms are moving from and moving to during biosynthesis.
Display slides 9-10 to have students compare their answers to the Matter Movement Question with the answers on the slide. Students only need to have arrows showing the movement of molecules into and out of the cell. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.
How do animal cells use small organic molecules to grow and divide?

9. Matter Movement Do you have:
an arrow showing small organic molecules or monomers going into the cow’s skin cell?
Small Organic Molecules or Monomers
Image Credit: Craig Douglas, Michigan State University
Display slides 9-10 to have students compare their answers to the Matter Movement Question with the answers on the slide. Students only need to have arrows showing the movement of molecules into and out of the cell. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

10. Matter Movement Do you have:
large organic molecules (or polymers) staying in the cow’s skin cell?
Small organic molecules or monomers
Large organic molecules or polymers
Image Credit: Craig Douglas, Michigan State University
Display slides 9-10 to have students compare their answers to the Matter Movement Question with the answers on the slide. Students only need to have arrows showing the movement of molecules into and out of the cell. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

11. The Carbon and Energy Questions:
What happens to small organic molecules during biosynthesis?
The Matter Change Question
Chemical change
Image Credit: Craig Douglas, Michigan State University
Have students think about how biosynthesis answers the Matter Change Question.
Show slide 11 to begin discussing the Matter Change Question.
Display slides to have students compare their answers to the Matter Change Question on the 5.4 Explanations Tool for Cow Biosynthesis with the answers on the slide. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.
Refer to the Digestion and Biosynthesis 11 x 17 Posters in your classroom to help students visualize the biosynthesis of monomers to polymers.
Small organic molecules (monomers)
go into cells, but don’t come out. What happens inside the cells?

12. Matter Change
Name the chemical change that cow cells use to build large organic molecules: Biosynthesis
Display slides to have students compare their answers to the Matter Change Question on the 5.4 Explanations Tool for Cow Biosynthesis with the answers on the slide. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.
Refer to the Digestion and Biosynthesis 11 x 17 Posters in your classroom to help students visualize the biosynthesis of monomers to polymers.

13. Matter Change
What molecules are carbon atoms in after the chemical change? Large organic molecules (or fats/lipids, and proteins) What other molecules are produced? Water
What molecules are carbon atoms in before the chemical change? Small organic molecules (or monomers such as amino acids, sugars, and fatty acids) What other molecules are needed? None
Chemical Change
Display slides to have students compare their answers to the Matter Change Question on the 5.4 Explanations Tool for Cow Biosynthesis with the answers on the slide. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.
Refer to the Digestion and Biosynthesis 11 x 17 Posters in your classroom to help students visualize the biosynthesis of monomers to polymers.

14. Energy Change
What forms of energy go into this chemical change? Chemical Energy
What forms of energy come out of this chemical change? Chemical Energy
Energy Transformation
Discuss how biosynthesis helps answer the Energy Change questions.
Display slide 14 to have students compare their answers to the Energy Change Question on the 5.4 Explanations Tool for Cow Biosynthesis with the answers on the slide. Have students use a different colored writing utensil to make any needed changes to their answers. Allow students to ask questions if they do not understand why their ideas are incorrect.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

15. Telling the Whole Story
Question: How does a skin cell in the leg of a cow use food to grow and divide?
Does your story include these parts? (Check the back of the Three Questions Handout.)
Matter movement: Small organic molecules (or monomers, such as amino acids, sugars, fatty acids, and glycerol) enter the cow’s skin cell.
Matter change: The small organic molecules are combined to make large organic molecules ( or polymers, such as carbohydrates, fats/lipids, and proteins).
Energy change: The chemical energy stored in the C-C and C-H bonds in the small organic molecules (monomers) stays in these bonds when they are combined into large organic molecules (polymers).
Matter movement: The cell grows bigger and may eventually divide as more large organic molecules (polymers) are made.
(Optional) Have students critique example explanations.
Display slide 15 of the PPT for the full story of digestion. Have students look at two handouts: (a) The Three Questions Handout, and (b) the Animals Example Explanations Handout.
Ask students to evaluate the two example explanations of cow biosynthesis on the Animals Example Explanations Handout: Which explanation is better? Why?
Have students use the Three Questions Explanation Checklist on the back of the Three Questions Handout to justify their critiques of the explanations.
Have students critique and improve their full explanations.
Display slide 15 of the PPT for the full explanation. Have students use the Three Questions Explanation Checklist on the back of the Three Questions Handout to check that their story includes each of the parts (matter movement, matter change, energy change, and matter movement).
If students don’t have all four parts in their explanation, instruct them to add to their explanation using a different colored writing utensil.
If students have model explanations to share, display student work and discuss. If students have common areas of weakness in their explanations, ask for a volunteer to share, display student work, and discuss ways of strengthening the response.

16. Discuss with a partner
Have students connect their atomic-molecular explanations to the macroscopic scale by referring to the cow poster.
Show slide 17. Have students look at the Cow 11 x 17 Poster and discuss with a partner the parts of a cow involved in digestion and biosynthesis on a macroscopic scale.
Tell students that all parts (all cells) of a cow’s body undergo biosynthesis.

17. How have your ideas changed?
Gather together your process tools for the unit (Expressing Ideas Tool, Predictions Tool, & Evidence-Based Argument Tool).
How have your ideas changed related to:
Scale?
Movement?
Carbon?
What do you know now about how cows use food to move and function that you didn’t know before the investigation?
Lead a discussion about how student ideas have changed over time.
Show slide 17 of the 5.4 Explaining How Cows Grow: Digestion and Biosynthesis PPT. Have students look back over their process tools for this unit.
Have students consider how their ideas changed with regard to scale, movement, and carbon.
What do they know now about how cows use food to move and function that they didn’t know before the investigation?

18. Revisit unanswered questions
Which unanswered questions can you now answer with what you understand about digestion and biosynthesis?
Which questions are left unanswered?
Do you have any new questions to add?
Revisit unanswered questions.
Show slide 18. Have students look at their 5.4 Explaining How Cows Grow: Digestion and Biosynthesis PPT. Display the class list of unanswered questions from Activity 3.3.
Ask students which of their unanswered questions they can now answer with their understanding of digestion and biosynthesis. Which ones are left unanswered? Do they have any new questions to add to the list?
(Optional) Have students complete the Big Idea Probe: What Happens to the Fat? for the second time.
If you decided to use the Big Idea Probe: What Happens to the Fat?, have students complete it and share their ideas for a second time. See Assessing the Big Idea Probe: What Happens to the Fat? for suggestions about how to use the Big Idea Probe.