Modeling Cellular Respiration (Part 1/2)

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Students will compare the rates of cell respiration in germinated and non-germinated seeds at various temperatures.

Big Idea

Every living thing needs cellular respiration...I mean, everything.

What Students will Learn in this Lesson

1 minutes

In this lesson, students will compare the rate of respiration between germinated and non-germinated seeds. This day 1 of a two day lessonHere is an overview of what students will learn today.

Hook/Check for Understanding

3 minutes

Revisit the germinating seeds assessment probe to remind students the difference between germinated and non-germinated seeds.  

Ask students the following questions:  

  • What raw materials might have been available to help in the germination of these seeds?
  • What products are being made by the germinated seeds that are not being made by the non-germinated seeds?

Students should record their responses in their lab notebooks.  

(Note:  When I first introduced this assessment probe, I actually assembled it.  By this time, the seeds have germinated and have form parsley plants.  As a class, we open the bell jar.  Students are able to examine the seeds in the peat moss pellets. They should notice that some have germinated and some have not germinated. I have my students consider why some seeds have not germinated.)


Student Lab: Determining Respiration Rate

30 minutes

This student lab is based on a lab from Vernier.  (Note: I use the lab with some minor modifications that are described below.)

The following equipment is needed for this lab.

  • Vernier Labquest
  • Logger Pro
  • Vernier carbon dioxide gas sensor
  • Vernier oxygen gas sensor
  • Vernier temperature probe
  • Biochamber 250
  • 25 germinating peas
  • 25 non-germinating peas (dried peas)
  • distilled water
  • tap water
  • ice cubes
  • 2 100mL beakers
  • paper towels
  • KimWipes
  • Hot plate
  • 250 mL beaker


Using germinated and non-germinated peas that have been incubated at room temperature, in a cold water bath, and a warm water bath, the amount of oxygen gas and carbon dioxide gas released will be measured.  Then the rate of respiration and rate of consumption will be determined by calculating a regression line.  

See Determining the Rate of Cell Respiration student lab worksheet for more detailed instructions. 

Putting It All Together: What Our Results Mean

15 minutes

Students should share and compare their results.  They should discuss the implication of their data by considering the differences seen between germinating and non-germinating seeds.  They should also consider the effects temperature has on the respiration rate. 

  • What evidence shows that cell respiration is occurring in peas? 

Possible student answers:  The amount of oxygen in the biochamber is going down and the amount of carbon dioxide is going up.

  • What is the effect of germination on the rate of cell respiration in peas?

Possible student answers:  As peas germinate, the rate of cell respiration goes up. 

  • What is the effect of temperature on the rate of cell respiration in peas? 

Possible student answers: As temperature increases, the rate of cell respiration goes up.

  • What do germinating peas need to undergo cell respiration?

Possible student answers: Germinating seeds needs oxygen and sugar to undergo cell respiration.

After the class discussion, students should summarize their findings in their lab notebook.  Students will need to turn in their lab notebook for evaluation at the end of the period.