need more information

[dhara]

HELLO,
AS YOU KNOW I AM DOING THIS EXPT ON YEAST, HOW CAN I PUT CONTROL BECAUSE MY TEACHER WANT US TO HAVE CONTROL.ALSO CAN I DO THIS EXPT LIKE 15 MINUTES OF AERATION, 30MINUTES OF AERATION AND 60 MINUTES OF AERATION BECAUSE WE REALLY NEED
THREE OR MORE VARIABLES FOR EXPT. CAN YOU GUIDE ME IN THERE?
THANK YOU.

[MelissaB]

First, do you know what a control is? If not, take a look at our project guide site.

You should also post all your questions to the same thread rather than making new ones. It makes it easier for us to remember who you are and what you're doing.

There are several controls that come to mind for this experiment: two extra bottles, one with just warm water in it and one with just cold water in it, two extra bottles with just yeast but no sugar, and two extra bottles with no yeast but sugar. Can you see how each of these would control for something?

You could certainly vary the amount of time you collect the gas and see if it has an effect on the amount of gas collected.

[dhara]

HELLO MS, MELLISA,
THANK YOU FOR ANSWER I LEARNED A LOT OF THING TALKING WITH YOU ON E MAIL.I KNOW THAT I CAN GET AMOUNT OF GAS COLLECTED ,COULD BE TIMED BUT I WANTED TO KNOW IN "+AIR" BOTTLE CAN WE PUT DIFFERENT VARIATION OF AIR IN DISSOLVED FORM , THAT IS IF I PUMP AIR AND SWIRLE FOR 5 MINUTES AND COLLECT THE CO2. THEN I PUMP AIR FOR 10 MINUTES AND GET THE CO2 READING.AND FINALLY WITH 15 MINUTES. I DONOT KNOW IF THAT CAN BE DONE OR WHERE CAN I GET RESEARCH ABOUT DISSOLVED OXYGEN .
THANK YOU.

[MelissaB]

Rather than pumping the air more, I would suggest using cooler water--but yes, you could certainly do that (assuming you are talking about adding more variables and not about the control).

If you put something like 'dissolved oxygen content of water' into a search engine like google, you will find hits to a lot of websites that have information about dissolved oxygen. Can you tell us what grade you are in? If you are in high school, you can put the same thing into google scholar and will get scientific research papers about the topic.

[dhara]

HELLO,
I AM IN 6TH GRADE AND I DO NEED CONTROL BUT AS I TOLD I NEED THREE VARIABLES WE HAVE LIKE AEROBIC AND ANAEROBIC BUT I WAS THINKING IF I CAN DO KIND A PARTIAL AERATION THATS WHY I WAS ASKING YOU ALL THAT QUESTION AND WHERE CAN I FIND PHYSICS PART OF THIS EXPT'S RESEARCH, I MEAN WHAT I SHOULD PUT FOR SEARCH ? YOUR HELP GIVES ME BIG SUPPORT FOR THIS EXPT AND MY MOM AND ME REALLY APPRICIATED THIS.
THANK YOU VERY MUCH.

[deleted-71447]

Hi dhara,
The level of aeration (or dissolved oxygen concentration) is one variable. By varying the amount of oxygen in the water, you would be testing the effects of that single variable.

Did they ask you to identify three variables in your project? I would guess that they do not want you change three variables. Usually, you try to keep all variables constant, except for the variable that you are testing, which, in this case, is oxygen concentration. Other variables would be anything that could possibly affect the outcome of your experiment. Do you need more help with that?

Also, would it be possible for you to type in lower case letters? The all-upper case is a bit difficult to read. Thanks.

Chris

[geoffbruton]

Hi dhara!

I agree with Melissa's post, and would be especially interested to see how the yeast metabolism is affected by temperature. Perhaps that could be one of your variables?

Also, in your experiment, will the flasks be agitated? It might be interesting to see how the amount of agitation of the flasks affects the amount of metabolism, especially since you are also investigating the yeast metabolism with and without aeration.

Please consider how these may fit into your current experimental design and hypothesis and let us know your thoughts.

Good luck!
Geoff.

[dhara]

HELLO,
I STILL HAVE TO RESEARCH ON PHYSICS PART OF THE EXPT AND IF YOU KNOW SITE OR TITLE I SHOULD PUT IN SEARCH ENGINE WILL REALLY HELP ME. I DID MY RESEARCH ON YEAST, AEROBIC AND ANAEROBIC RESPIRATION AND DO YOU THINK BESIDES PHYSICS PART OF EXPT ANY OTHER RESEARCH I SHOULD BE DOING? YOU GUYS MADE THIS EXPT SO INTERESTING I CAN'T WAIT TO DO IT AND GIVE YOU THE OUTCOME.
THANK YOU VERY MUCH

[geoffbruton]

Hi dhara,

I'm not quite sure what you mean by "the physics part" of your experiment.

Could you please expand upon what it is that you're trying to find out? We should be able to provide more help if we know specifically what you are asking.

Thanks - and we're very pleased to hear that you're so excited about your project! We can't wait to hear your results!

Geoff.

[dhara]

HELLO,
IN MY QUESTION I SAID PHYSICS PART MEANS IN THE EXPT I HAVE TO SET UP THE MATERIAL LIKE GRADUATED CYLINDER UPSIDE DOWN AND IT HAS TO BE TOTALLY FILLED WITH WATER EVEN IT IS IN WATER TUB , SO WHAT PROPERTY OF WATER OR SOMETHING I NEED TO FIND TO EXPLAIN THAT PART OF THE EXPT ALSO WHEN CO2 COLLECTED IN THE GRADUATED CYLINDER, CO2 REPLACES WATER , I NEED TO FIND RESEACH SITE, BOOK OR SOMETHING FOR MY RESARCH LOG. I WANTED THAT PHYSICS PART TO BE RESEARCHED. THANK YOU VERY MUCH.

[geoffbruton]

Hi dhara,

Okay, I think I understand the information that you need. Basically, the principle you are using in order to determine the amount of carbon dioxide generated is a form of water displacement. The fact that you are using a graduated cylinder will allow you to actually measure the volume of the carbon dioxide (a gas) that is produced during each experiment. This is actually a very clever way of measuring the volume of a gas!

Now, as you already know, carbon dioxide is a gas. Simply put, the gas is less dense than water, which causes it to rise through the water as visible bubbles. These bubbles, once they reach the closed top of the cylinder, will collect and exert a pressure on the water already present in the container - and consequently force the water down and out of the cylinder. The more gas that is collected, the more water that is displaced - and you can read the volume simply by reading the side of the graduated cylinder.

(Incidentally, carbon dioxide is also partially soluble in water, but hopefully for the purposes of this experiment, the amount of gas that will dissolve will be unimportant when you compare the "+air" and "-air test" results.)

If you need a particular reference for this information, you may want to try searching for some of the terms I used, using your favorite search engine. Also try some alternate words and see what you can find.

Please keep us informed of your progress.

Good luck!
Geoff.

[dhara]

Hello Chris G,
I think you understood, I want to change my variable as with air, without air and inbetween air that is different dissolved oxygen content of water.Now I have almost everything clear but to put different amount of dissolved oxygen is this will be a scientific method like pumping air for 5 minutes and swirling yeast+sugar+water suspention every minute and another with pumping for ten minutes and swirling suspention liquid every minute and third will be for 15 minutes and last with no air .Will this give me a good results , please tell me so this weekend I will do my first trail?
Thank you

[deleted-71447]

Hi Dhara,
Just for reference, this is the experiment that you are doing, right?
http://www.sciencebuddies.com/mentoring ... ?from=Home

I like your idea of pumping air for different amounts of time. The online procedure calls for aerating (pumping bubbles into) the deoxygenated water for 5 minutes, so I would use this as a starting point. As you pump air into the deoxygenated water, the concentration of dissolved oxygen will eventually stop increasing, so you might not see any difference between pumping 5 minutes and pumping 15 minutes. For starters, you could pump for 2.5 minutes and 5 minutes. If you get more CO2 after 5 minutes than after 2.5 minutes, you can try 10 minutes. If you get the same amount of CO2 with 2.5 and 5 minutes of pumping, you could try 1 minute. Do you see what I mean?

Another issue to consider is that the online procedure instructs you to leave a small amount of air above the water in the bottle with the yeast, but the procedure is not specific about how much air to leave in the bottle. Some of the oxygen from this air will diffuse back into the water during the experiment. Suppose you have 0.9 L of water and 0.1 liter of air. Air contains about 21% oxygen, so 0.1 liter of air contains 0.021 liters of oxygen, or 21 cubic centimeters (cc) of oxygen. Aerobic water contains about 6 cc of oxygen per liter, so 0.9 liters contains only about 5-6 cc of oxygen. This 5-6 cc is the amount of oxygen that you can control by boiling and re-aerating the water, and it is much less than the amount of oxygen in 0.1 L of air. So, be careful! If you leave some air in the bottle and are not very careful about how much air is in each bottle, it is possible that your "aerobic" bottle might actually have less oxygen than an "anaerobic" bottle. I recommend filling the bottles with as much water as possible (leaving as little air in the bottle as possible ) and also being very careful to leave the same amount of air in each bottle so that it won't complicate your results.

Chris

[dhara]

Hello,
How this yeast expt can be useful in real world where i can get more research about that ?Also did anybody has done this expt before because in my research log I can put if somebody has done this expt?I did just trial of the expt with air and without air and I am getting more co2 without air than one with air, do you think that results in real world situation are compatible. And if not where can I get more information?
thank you

[dhara]

Hello,
I asked question please someone relpy please , my project is due soon and I would really appriciate if my results of trial are correct and I will finish my expt sooner.
thank you

[geoffbruton]

Hi dhara,

With regards to why this experiment is applicable to the "real world" - did you read over the information and links contained in the bibliography provided in the Science Buddies Project Ideas for this project? I would also recommend typing some keywords into your favorite search engine and see what results you get. This should give you some great ideas as to why this particular project has a "real world" application. Please let us know what you find!

As for the results you have from your initial experimental run: what did you predict would happen based on your background reading? How many times did you run this experiment, and did you get the same results every time? Your results should be reproducible.

If you can, please post your experimental design to this forum and we can look over your method and try and see what may have happened.

Well done for getting started! We're really looking forward to hearing how your project is coming along.

Keep up the good work!
Geoff.

[deleted-71588]

How this yeast expt can be useful in real world where i can get more research about that ?

One of the references in the project is http://biology.clc.uc.edu/courses/bio104/cellresp.htm is more appropriate for a higher grade level. Let me translate a bit down to the sixth grade level.

Without Glycolysis and ATP, we wouldn't be alive. It is a very important metabolic pathway, essentially metabolism is how our bodies store food energy and later make use of it. A pathway is a specific chemical reaction process (Glycolysis or Fermentation).

More specific to your yeast experiment, I'm surprised that what you thought was an anerobic process (without oxygen) yielded more CO2 than what you thought was an aerobic process (with oxygen). I suspect some other factor like temperature, sugar concentration, number of viable yeast cells, or disolved oxygen (and factors that Chris G mentioned earlier) were involved.

Note: The project difficulty rating is 8 which means it is a stretch for a 6th grader to fully understand all of what is going on without doing a LOT of reading. It is more grade appropriate for somebody who has had or is taking high school biology.

What this means is that you are going to have to do some extra reading and look up a lot of words to understand their meanings because you haven't had exposure to those words yet.

There are numerous real world uses of fermentation. The production of beer, wine, and many antibiotics use fermentation processes.

The CO2 produced by yeast is used in producing many baked goods, cake, bread, and pastries.

Understanding the metabolic processes of yeast is the starting point for understanding the metabolic processes of more complex organisms.

[dhara]

Hello,
As I said my trial with the procedure exactly as in science buddy expt shows me more CO2 production in anaerobic condition than aerobic condition is not it should be ? If it is not then I have to see where I am making mistake.I had maintained the temperature for dissolved oxygen constant,also I boiled the water to take out all O2 and I didnot agitated the bottle also. So what else I should be careful and that means in reality aerobic condition shoul give more CO2.Please let me know,as always this is very good learnig experience and thank millions for all your help.

[deleted-71447]

Hi Dhara,
Without seeing your experiment with our own eyes, it is difficult to know why you got those results. The procedure on the Science Buddies website is not specific about some things (for example, the exact volume of airspace above the liquid), and, as Craig mentioned, there are lots of factors that could affect your results. There could be a small leak in one of the tubes. If the boiled water was exposed to the atmosphere while cooling, the dissolved O2 may have partly or fully re-equilibrated with the atmosphere. If the bottles were not exactly the same shape and size, you may have had different amounts of O2 in the airspace above the liquid. Probably, the difference that you see between aerobic and anaerobic trials is a result of some uncontrolled experimental errors. You can find out by running the experiment several times and seeing if you get the same result every time.

How much of a difference did you see between the aerobic and anaerobic trials? Please post your data if you can.

Thanks,
Chris

[dhara]

Hello,
I asked question please someone relpy please , my project is due soon and I would really appriciate if my results of trial are correct and I will finish my expt sooner.
thank you

[deleted-71447]

Dhara,
Do you have a new question? That is the same post that you made on Oct 8, so I am not sure if you are looking for more help, or if you just made a mistake.

[dhara]

Hello,
I did my trial two more times and I am still geting same more co2 production with anerobic condition than aerobic condition, so that shows that co2 production is more in anaerobic condition.Is this results look good?As I couldnot find real facts about the what should be the more favorable condition for co2 production in my research.
THANK YOU.

[deleted-71447]

Dhara,
Good work following up on your results.
I have been digging around for more information and I am finding that this experimental topic is more complicated than I originally thought. Here are a few key points to consider when you are interpreting your results.

(1) Aerobic respiration by yeast is a more "energy efficient" process than anaerobic fermentation.

(2) For each molecule of sugar consumed, anaerobic fermentation generates less CO2 than aerobic respiration. Fermentation has this general formula:

C6H12O6 → 2 C2H5OH + 2 CO2

C6H12O6 is a sugar molecule,
C2H5OH is alcohol
CO2 is carbon dioxide

Aerobic respiration has this general formula:

C6H12O6 + 6O2 → 6CO2 + 6H2O

From these equations, you can see that 1 sugar molecule will produce 2 CO2 by fermentation or 6 CO2 by aerobic respiration.

(3) Not all of the carbon from the consumed sugar goes to waste products like CO2 and alcohol. Some of the carbon is incorporated into the yeast cell as it grows and reproduces. The ratio of the increased cell mass to the mass of consumed sugar is known as the "biomass yield." For "bakers yeast" and other species of yeast, the biomass yield drops very quickly as the oxygen concentration drops. The change in biomass yield is so steep that a decrease in O2 consumption rate can actually cause an increase in CO2 production rate. These results are from a recent journal article: Lars Hanl, Peter Sommer, Nils Arneborg. The effect of decreasing oxygen feed rates on growth and metabolism of Torulaspora delbrueckii. Appl Microbiol Biotechnol (2005) 67: 113–118. I can provide a copy if you think it would be helpful.

(4) Your boiled water is not strictly anaerobic, because boiling water does not remove all of the oxygen...
http://www.science.edu.sg/ssc/detailed. ... t=4&cat=48
...and because some oxygen diffuses back into the water after it has boiled. Depending on your setup and how long you run the experiment, you might not ever have anaerobic conditions in either of your bottles.

Don't worry about a "good" or correct result. This isn't like solving a math problem. The best that you can do is to design and conduct your experiment with care, present your results with as much clarity and detail as possible, and provide reasonable interpretations of your results.

I hope that helps. Please let us know if you have more questions.
Chris