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Monday, March 5, 2012

Lab: The Use of Glucose in Cellular Respiration




<--- This is very difficult for many students who are attempting to master the details of cellular respiration!

Make your biology class more appealing and exciting by incorporating a variety of fun and interesting labs into your weekly lesson plans! This inquiry-based lab allows students to discover how yeasts use organic molecules as a source of energy and give off carbon dioxide as a waste product.

Cellular respiration may be one of the hardest topics that a biology teacher faces in their curriculum.  For many students, the concepts are vague and abstract, making them difficult to understand.  In order to teach a successful unit on cellular respiration, many "hands-on" activities are essential.

In this lab, we will try to determine these things:
1.  Is glucose required for cell respiration?
2. Is there a correlation or relationship between the amount of sugar available and the amount of carbon dioxide produced?
3.  Can any type of sugar be used as a fuel for cellular respiration?

To answer these questions, this 2-part lab will first have the student explore how the concentration of the glucose affects the rate of respiration.  Second, the student will conduct an experiment to determine if the type of sugar is important in the respiration process.

In the first part of the lab, the students will set up a serial dilution of glucose solutions ranging in concentration from 100% glucose down to .78% glucose.



After preparing the serial dilution, students add one mL of yeast solution to each glucose solution.  Now the fun part begins!  Students will pour the glucose/yeast solution into the small fermentation tube, then flip the tube upside down into the beaker containing the remainder of the glucose/yeast solution.

I use 50 mL beakers and very small test tubes.  These test tubes (10 x 75 mL) make excellent fermentation tubes.
The small fermentation tube is completely filled
with the glucose/yeast solution.
The yeasts will give off carbon dioxide as they
convert the glucose to ATP during  fermentation.

After 24 hours, the yeasts have given off enough
carbon dioxide to produce a very large air bubble
inside the fermentation tube.


In the second part of the experiment, the student will determine if the type of sugar is important in the process of cellular respiration.  The same procedure is used, but rather than change the concentration of the glucose solution, the student uses different types of sugars.

This lab is designed for a typical high school biology class for students in grades 9 - 12. It is appropriate for both standard and honors classes, as well as for first or second year biology students. I have used this lab in both my freshman biology I class as well as my AP biology class.

The lab materials needed for this experiment are simple and are commonly found in most science labs:
Yeast suspension
12  (50-mL) beakers
1  (100-mL) beaker
12 (10 x 75 mm) fermentation tubes
 Karo corn syrup (glucose)
Maltose
Sucrose
10 mL graduated cylinder



Happy Teaching!

2 comments:

  1. I just nominated you for two awards!! :) Check it out! Thanks for being an amazing teacher!

    ReplyDelete
  2. What should the results of the experiment be?

    ReplyDelete