Model Photosynthesis and Respiration with Berries

 

Students can model photosynthesis and respiration by making molecules out of strawberries, blueberries, grapes, and toothpicks. I wanted to create a healthier option to the gumdrops that are often used to model molecules, so I experimented with berries, and it worked nicely! 

You can use this activity when teaching Next Generation Science Standard (NGSS) MS-LS1-6: Construct a scientific explanation based on evidence for the role of photosynthesis in the cycling of matter and flow of energy into and out of organisms. It can also be used to teach MS-LS2-3: Develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem.

Students should prepare for this activity by first creating structural formulas for the reactants and products of photosynthesis and respiration. In a previous class, I provided a handout for students to draw structural formulas of all reactants and products of each process, referring students to this video (start at 6:10 for photosynthesis and 5:33 for respiration):

Chemistry Tutorial: Chemical Equations & Photosynthesis

As students draw their structural formulas, they begin to see that photosynthesis and respiration are opposite processes. 

On the day of the activity, students get directions for creating their berry models. Because carbon atoms are the largest of these atoms, I asked students to represent them using strawberries, the largest berries. The smallest atom, hydrogen, is represented by the smallest berry. Toothpicks are used as bonds.

Strawberries = Carbon Atoms

Grapes = Oxygen Atoms

Blueberries = Hydrogen Atoms

With the structural formulas they created previously in hand, students begin by creating molecules of water and carbon dioxide, the reactants of photosynthesis. You could allow students to work with a partner though you may want students to handle their own berries to prevent the spread of germs. The photo below shows students who successfully completed this first step (one water molecule not shown in the frame).

After building the reactants of photosynthesis, the next step is to model photosynthesis by breaking the bonds in water and carbon dioxide molecules and rearranging the atoms to form glucose, the product of photosynthesis.

The last step is to model respiration by breaking apart the glucose molecule to form the products of respiration, carbon dioxide and water. Students end with the same molecules they started with.

Once students have their hands-on work checked by a teacher and write about the relationship between photosynthesis and respiration, they can eat all the berries. One student told me afterward that she had never really “gotten photosynthesis and respiration” before but understood it now!

If you are interested in another activity that involves playing around with food in the name of science, follow this link to my previous blogpost on making models of cells using pasta and toppings:

Edible Cell Model Made of Pasta

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Edible Cell Model Made of Pasta

Students have fun learning about cell organelles with a buffet-style cell biology lesson! After studying the functions of different cell parts, students create an edible model of a cell using different kinds of pasta and toppings. You can use the activity when teaching Next Generation Science Standard (NGSS) MS-LS-1-2. Develop and use a model to describe the function of a cell as a whole and ways parts of cells contribute to the function.

This activity is best done after students have learned the basics about cell parts and their functions. In my classes, students first completed a cell model on paper and did some written work describing what each cell organelle does. They also studied how different cell parts work together. Before eating their model, students needed to be prepared to tell me some of this information using the model. It was my experience that making pasta cell models was something they looked forward to and served as a nice reward.

If you are leading this activity with a class, requesting parent donations of items needed for making the cell models, if possible, can save you some time and money. I emailed parents a Google doc where they could sign up to donate ingredients. 

Below is a list of items I have used for classes of about 25-28 students. This list seemed to serve the requirements of many different students I had, but you may want to adjust this according to the dietary needs and preferences of your particular group.

2 packages spaghetti

1 package spaghetti- gluten free

2 packages regular lasagna noodles

1 package lasagna noodles- gluten free 

1 package mini wheels pasta

4 jars red pasta sauce- no meat or dairy and gluten free

3 cans black olives

Dried oregano and/or basil

1 package frozen peas

1 can cannellini beans

1 can kidney beans

7 small, thin zucchini (slice into circles and fry)

2 packages cherry/grape tomatoes

4 boxes toothpicks

Be prepared with small bowls and/or plates for students to use when creating their models as well as forks for eating it. We always had leftover items, so having empty food containers on hand is useful.

If you plan to do this activity, it is best to have some extra hands to help you. I always had an assistant and/or a parent volunteer or two help with food preparation before the lesson and clean-up afterward. They helped prepare for the activity by boiling the pasta, cutting and frying the zucchini, warming the frozen peas, and putting ingredients into bowls with spoons to serve. 

If you are unable to arrange an extended class period to make the cell models, it’s a good idea to have students make little toothpick flags as labels for the cell parts the day before. 

Once students have made their flags and all the food is prepared and set out, students can get into the buffet line and use the ingredients as they like to create their cell model. Giving suggestions can help get them started. Students should decide whether they will create an animal or a plant cell, and this will determine whether they will need to create a border of one layer- just a cell membrane- or two- a cell membrane and a cell wall. These parts could be made using lasagna noodles or spaghetti. The green peas work well as chloroplasts for those students making plant cells. Zucchini slices are a nice size for the cell nucleus. Because ribosomes are very tiny, sprinkling dried herbs on the top works well as a model for ribosomes. Spaghetti with red sauce works well as a model of cytosol.

After creating and labeling the cell model, students show it to the teacher or assistant, naming and explaining the jobs of a few cell parts, and giving an example of how two cell parts work together. Then they can eat it!

If you would like to see other blogposts related to cell biology, follow these links:

Personality Quiz with Plant Cell Parts

Cell City: Cell Organelles Project

Illustrating Science Vocabulary: Plant Cell Organelles

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