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Red Cabbage pH Indicator in Respiration Labs

A new twist on using cabbage juice?

Most every science teacher is aware that the juice extracted from red cabbage makes an excellent acid/base indicator.  But at our school, we recently used it for a different (but related) purpose.  Our biology classes do a cellular respiration lab in which the students observe the production of carbon dioxide during respiration.  Normally we use phenol red as an indicator.  Our supply of phenol red was running low and we looked for an alternative.  The answer was cabbage juice indicator!!

How was red cabbage used as an indicator of carbon dioxide?  I'll come back to that in a minute.  First, here is a little background about red cabbage......

Background:   Red cabbage contains a natural pH indicator in the form of the pigment, anthocyanin.  It is a water soluble pigment that is commonly found in nature in red cabbage, of course, as well as purple plums, grapes, and apples.  Red cabbage juice will turn a wide variety of colors in the presence of acids and bases.  In a neutral solution, the cabbage is a fairly dark purple color.  In the presence of acids, the cabbage juice will turn red/pink, and in the presence of bases, the cabbage juice turns a greenish-yellow color.

How to Make Cabbage Juice Indicator:  This process is so simple that I usually allow my students to make their own indicator.  Simply chop up a head of red cabbage.  Place a small handful of cabbage leaves into a beaker.  Cover the leaves with water and boil for about 15 minutes.  As the cabbage boils, the pigment will be extracted from the leaves and the water will turn a dark purple color.  Use a slotted spoon to remove the cabbage, or pore the solution through filter paper.  Your indicator is now ready to use!

Our Cellular Respiration Lab:  In order to complete the chemical reactions of cellular respiration, oxygen is required.  Carbon dioxide is released during the reactions and is given off as a waste product.    Although it is very difficult for us to observe the conversion of glucose to ATP, it is possible to observe the gas exchange that must take place in order for respiration to be carried out.   The lab that we do at our school has three objectives:
1.   To observe the release of carbon dioxide during cellular respiration in animals.
2.   To determine if plants carry out the same gas exchange as animals.
3.   To observe, record, and analyze the results of an acid-base indicator.

In the first part of our lab, the student will learn how to use the cabbage juice to indicate the presence of carbon dioxide.  (See above photo.)  Carbon dioxide and water will react to form carbonic acid.  Since our breath and carbonated beverages contain carbon dioxide, the color change from dark purple to pinkish/red indicates the formation of carbonic acid.

In the second part of the lab, we want the student to determine if plants also give off carbon dioxide during cellular respiration.  As you can see in the above photo, the first tube serves as a control, the second tube contains germinating seeds, which have a high rate of respiration, and the third tube contains dry seeds, which are alive, but dormant.  The photo clearly shows that the germinating peas are releasing carbon dioxide.  (Since the peas are not photosynthetic, they are not consuming carbon dioxide.)  In the tube containing the dry peas, there is a very slight color change that does not show clearly in this photo.  The dry seeds do carry out cellular respiration, but at a very slow rate.  The results seen in the above photo were obtained after allowing the tubes to sit for just 24 hours.

This lab is easy to set up, easy to clean up, and best of all, our students really enjoy doing it.

Happy Teaching!

Click image to view product on TpT.

Grizzly Bears

Well, my Spring Break is almost to an end.  I am rested and looking forward to returning to school on Monday.  My students and I will spend the remainder of the school year on a mad dash toward May 14..... the date of the AP Biology exam!   I will end this week with the last of the photos from our zoo trip.  Next week, I will be back to posting about what is going on in the biology/chemistry classroom.

One of the newest areas in our zoo is called "Northwest Passage."  This area houses the polar bears, elk, wolves, etc.  But one of the most amazing sections is the Grizzly Bear enclosure.  First of the all, the area in which they can run and play is huge.  It starts with a huge waterfall at one end, and a stream/river runs the entire length.  The stream is stocked with live fish!  The bears spend much of their time playing in the water and fishing!  It is amazing to watch as they stalk and catch a fish.  I hope you enjoy these pictures.


This week is "zoo picture" week on  Science Stuff.  Today is Reptile Day!

We arrived at the Komodo Dragon enclosure
just at feeding time.

They receive a different food each day.
 This day it was a large rat and duck eggs.
The rat disappeared immediately!  

This python is about 20 feet long!


This week is "zoo picture" week on Science Stuff!

As you read yesterday, I am on Spring Break this week.   We made a wonderful trip to the zoo early in the week, and each day I am posting pictures from that trip.

Today is for the birds!

The eagles are magnificent.
These eagles were injured in the wild
and are no longer able to survive on their own.
Eagles cannot be kept in zoos otherwise.

We went to the Zoo!

It is Spring Break in our neck of the woods.  I am enjoying a much needed break from teaching school!  I absolutely love teaching, but everyone needs a break from their job from time to time, and teachers are no exception.  I will be energized and ready to jump back into the school routine next Monday.

I am so thankful that my oldest daughter, who is in college now, has spring break this same week.  Yesterday was a gorgeous day, sunny and 82 degrees.  The entire family went on a zoo adventure, so I though I would share zoo photos with you this week.

Our first stop was a new "Dino Digs" exhibit.
It is really for the little kids, but us big kids love it, too!

I love that my grown daughters are still so playful
and still enjoy going to the zoo with their mom!
We caught the cheetahs sunbathing!

Our zoo has made remarkable progress in the 30 years
 we have lived in this area.  Most of the enclosures
are new and offer wonderful living spaces for these animals.

The hippo enclosure is one of the last areas to be updated.
This area was built in the 1950's.

A new hippo area is being built and will be ready within the next year.
 It will be called Zambizi River Camp and will offer these
magnificent animals a new state of the art home.

The meerkats are definitely a family favorite!

Our zoo was successful in obtaining a pair of pandas on loan from China.

One of the newest areas of our zoo is called Northwest Passage.  It houses the polar bears, grizzly bears, wolves, and sea lions.  The polar bear area is one big water playground for these guys!

Not a great picture because of the angle of the sun, but it was such a great pose!

Over the next few days, I will be posting on the grizzly bears, the reptiles and the birds.  Enjoy!

The Atoms Family: Teaching About Atoms and Energy With a Monster Theme

This site makes learning about atoms, molecules and energy fun!

I recently came across this site while surfing the net for some new and fun science activities.  It is called "The Atoms Family", which I found amusing.  It is a spoof on the old television show called "The Adam's Family."  Don't worry, there is nothing scary on this site.....just a lot a really, really fun science activities and experiments.  It is based on The Atoms Family exhibit at the Miami Science Museum.

The stie is divided into these five general areas:

  1. The Mummy's Tomb:  Learn about energy conservation, kinetic, and potential energy.
  2. Dracula's Library:  Learn about the properties of light, waves, and particles.
  3. Frankenstein's Lightening Laboratory:  Learn about different forms of electricity and electrical safety.
  4. The Phantom's Portrait Parlor:  Learn about the principles of atoms and matter.
  5. The Wolfman's Ghostly Graveyard:  Learn about fuel conservation and energy transfer.
Each of the above areas offers several activities to choose from based on the age of the child.  Some activities are aimed at younger elementary children, while others are more suitable for middle school children.  These activities can be carried out in a school classroom, or easily done at home.  All of the activities can be done with simple, easy to find materials.

Some of my favorite activities included:
  • Making a Christmas light shine using a lemon
  • A paper cutting activity that demonstrates the size of an atom
  • Building a marble racetrack to show the differences in potential and kinetic energy.
All in all, I found this site to be both fun and educational!

Happy Teaching!

Have you heard of The Lesson Cloud?

Check out The Lesson Cloud!

The Lesson Cloud is a collaborative blog that has 100 teacher/authors from every grade level and every subject area.  Each and every day there are so many new posts about great teaching ideas, crafts, tips, etc.  There are links to paid products, but there are just SO MANY free materials that are posted to The Lesson Cloud every day.  The Lesson Cloud has a "Free Product Archive".  It is arranged by subject area and you can always find the perfect teaching lesson in the archive of free materials.  Read below about the special week taking place on The Lesson Cloud.  Be sure to follow the blog, and follow us on facebook!

This week (March 10 - 17) is March celebration month on The Lesson Cloud!  We are celebrating St. Patrick's Day, Earth Day, Spring Breaks from school, March Madness.....well, we are just celebrating life in general this week!  So check back every day and check back often because there will be tons and tons of posts for every grade level and every subject area.  The 100 leprechauns (authors) of The Lesson Cloud will be showering you with gold in the form of a load of freebies each and every day this week, along with great articles and links to some paid items.

Help us spread the word!  We would be thrilled if you would mention us on Twitter, Facebook, Pinterest, or give us a shout out on your blog.  Tell everyone that The Lesson Cloud is going GREEN and it is not to be missed!

Happy March, everyone!

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)
10 mL graduated cylinder

Click image to view this lab in my TpT store.

Happy Teaching!