Unit 3: Cellular Respiration

(The Lab Formerly Known as Cereal-ular Respiration)

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Learning Objectives

  • • Develop an understanding of how the food that we consume is converted into energy through cellular respiration
  • • See how changing the amount of different reactants can change the rate of cellular respiration
  • • Practice using a proxy as a method of measurement when designing an experiment

Observation

Dr. Nystrom
Dr. Nystrom
Lead Scientist

I was training for a marathon last year! What a crazy idea. Anyway, as I trained, I learned that a really important aspect of training for a marathon is learning how to eat while you are running and figuring out the right foods to fuel you for multiple hours of running. The foods I ate ranged from ramen noodles to peanut butter and jelly to candy to energy gels.

I was baffled by the bursts of energy that I would get after eating a handful of gummi bears vs. the slightly slower release of energy that a peanut butter and jelly sandwich would give me. Of course, this got me thinking about how our bodies metabolize food and convert it into energy.

I went searching around in my brain library, and I found something about how cellular respiration is one way that our body produces energy from the sugars that we consume. Then I began to wonder how the foods I eat during running affect me. How could they change the rate of cellular respiration and therefore my rate of energy production?

Background

A deeper dive into cellular respiration can be found in Cellular Respiration (AP Bio - Unit 3.5)

Cellular respiration is the process by which cells convert the energy found within the simple carbohydrate, glucose, into the energy currency of our cells called ATP (adenosine triphosphate). The equation for cellular respiration is as follows:

Glucose + Oxygen → Carbon Dioxide + Water + ATP

One can change the rate of cellular respiration by changing the amount of available glucose to be used in the reaction.

Research Question

How do foods with different sugar content affect the rate of cellular respiration?

Hypothesis

Write your hypothesis below:

Materials and Methods

Experimental Design Note

Although we don't have the tools at home to measure the amount of ATP produced, we can measure the rate of reaction by measuring another product of the cellular respiration reaction → carbon dioxide. In this experiment, we will capture carbon dioxide by using disposable gloves.

Materials

Warm Water
Active Dry Yeast
3 types of cereal with different sugar contents
9 disposable gloves
3 glasses (mason jars or a glass with a lip on it is ideal)
3 plastic bags
Timer

Protocol

  1. Record the sugar content of each cereal in the data table below
  2. Choose a glass for each cereal, and label them accordingly
  3. In separate plastic bags - Mash up each cereal into a coarse dust
    Note - It doesn't matter how fine the cereal dust is, as long as all 3 cereals are mushed up to the same consistency
  4. In each glove place the following things:
    • 2 tsp yeast
    • ¼ cup respective cereal
  5. Add ½ cup warm water to each glass
    6. NOTE - As you do the next step, make sure that the disposable glove remains "flopped over" so that none of the contents go into the water
  6. Stretch each disposable glove filled with cereal over the top of the correctly labeled glass. If you are using mason jars, you can stretch the glove over the ridges at the top of the glass to make it stay. If you are using a smooth glass, secure the glove with tape.
  7. As quickly as possible, lift each glove up so as to empty the contents of the glove into the glass
  8. Swirl each glass so that the water, yeast, and cereal mix
  9. Record which glove stands up 1st, 2nd, and 3rd
  10. Repeat this experiment 3 times, using a new glove and a clean glass each time. You can use the same plastic bag to mush up the cereal

Data

Record results in the data table below.

Cereal Sugar Content Order of glove standup - trial 1 Order of glove standup - trial 2 Order of glove standup - trial 3

Discussion

  1. What is the general trend of the relationship between rate of cellular respiration and sugar content?
  2. This experiment does not have a negative control - what could be added as a negative control?
  3. Did your results support your hypothesis?
  4. What are the limitations of this experiment?
  5. What else do you think could affect the rate of cellular respiration?
  6. How do you think artificial sweeteners would affect the rate of cellular respiration?
    • What experiments could you do to answer the above question?
  7. What are some other questions that you could ask using a similar experimental set up?