Here is an overview video I use to summarize the purpose of biomolecules, specifically carbohydrates and its connections to cellular respiration. Its important for students to understand that “We Eat because we need Energy”. This way, students can connect their food analysis lab with future and past concepts.
This lab uses a variety of food items. You can absolutely buy them if you like, but it’s cheaper and more convenient to ask students to bring specific food items to test. I used the following food items: Apple slices, American cheese, Oreo cookies, grapes, cereal, Gatorade, milk, vegetable cooking oil, apple juice and water (as a control variable).
Biomolecules Review Table
I wanted to share this Biomolecules Review Table since I find many of my scholars struggling with this concept. I find it easy for students to organize their ideas in one table and then use it as a review or notes as they move into enzymes.
You will need to buy Sandwich bags and prepare the following. You will repeat this process for as many groups as you like.
8 Test Tubes
Students will need to rinse after each test
24 Disposable Pipettes
(Tip: Students should be wearing their personal protective equipment PPE for all labs. Lugol’s Iodine Reagents will stain hands and clothing and cause skin rash. If ingested it can cause abdominal problems.)
Brown Paper Napkins
Ziplock Bags (Pre-filled) with different food items
Add enough samples for all your classes
Let your students know to only grab what is necessary since you will be using this for all your classes.
Cups (Pre-filled) with different liquid items
Have 1 Water Bath for the whole class so you can monitor or 1 per group *** At teacher discretion
Overall, I made 6 sets (6 groups) of food baggies and it was more than enough to last me 3 class periods. I gave students the option to test their own items as well. (Tip: add the food items in different baggies and let students know these will be used by your other classes).
You will need to place brown paper or newspaper (approx. 4 precut pieces), Biuret Reagent, Benedict’s reagent, Iodine-Lugol’s Reagent, and 8 test tubes with disposable pipettes and it’s rack in each group. (Tip: prepare your stations before students arrive into your classroom)
Students will begin to test their items. Students will analyze the presence and absence of biomolecules in different food samples using chemical indicators and then jot down their observations. (Tip: Go over each reaction and its meaning with your students or provide them with a cheat sheet so they can have a guide as they complete their activity.)
(Tip: Please note you will need a water bath for the glucose test. You will need to heat the test tubes once the benedict’s solution is added. Therefore, I recommend you only have 1 water bath for the whole class.)
After students finished their hypothesis, data table, analysis and conclusions, they were allowed to eat certain food items. By the end of the lab, students had an understanding of the different biomolecules that are present in the most common types of food items they consume.
They had to answer questions regarding “which substances had either carbs, proteins or lipids present in them?” and determine the variables of this experiment.
Overall, students had a really fun time, were engaged and learned the learned about proteins, carbohydrates and lipids. If you would like to check out the lab worksheet and cheat sheet I used for this lesson, you can find it on my TPT Store.
