• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

The Effect Of Glucose Concentration On The Activity Of Various Yeasts

Extracts from this document...

Introduction

The Effect Of Glucose Concentration On The Activity Of Various Yeasts Aim / Prediction - I intend to investigate what effect, if any, varying concentrations of a glucose solution has on the activity of two different types of yeasts. I predict that yeast activity will continue to rise as the concentration of the glucose solution increases, but will maybe have an optimum point at which the yeast can no longer withstand the high concentration in glucose. This applies to both of the yeasts, although I think that bread-making yeast will be more tolerant of glucose than brewers yeast. There will be a positive correlation between glucose concentration and yeast activity. Null Hypothesis (HO) - Varying glucose concentrations will have no effect on yeast activity. Alternative Hypothesis (H1) - Varying glucose concentrations will have no effect on yeast activity. Background - Yeast is any of a number of microscopic, unicellular fungi important for their ability to ferment carbohydrates in various substances. Most cultivated yeasts belong to the genus Saccharomyces; those known as brewer's yeasts are strains of Saccharomyces cerevisiae. Yeasts are used generally in the making of bread and alcohol, but their cultivation and use in large quantities are used industrially in a wide range of fermentation processes. Glucose Carbon Dioxide + Ethanol The yeast metabolises the sugar and produces carbon dioxide and ethanol, which takes place either aerobically or anaerobically. According to the theory of natural selection, changes take place in populations because individuals with the most favourable characteristics are most likely to survive and produce young. ...read more.

Middle

This has given the 5% solution (5% glucose). ii) Stir thoroughly with a glass rod. 6. 0% solutions should be 100% pure deionised water. 100% solutions should be 100% 1.00M glucose. As it is a 100ml measuring cylinder, translations into a percentage are fairly simple. For example, a 55% solution would need 55ml of the 1.00M glucose solution diluted to 100ml with deionised water, so this would mean adding 55ml glucose : 45ml water, for the 55% solution. NB: the above is the easiest method, though if this becomes a wasteful technique, a simple sum can be used to reduce the volumes of liquids used. For example, rather than using a 100ml measuring cylinder, use a 50ml measuring cylinder, therefore, halving the volumes of deionised water and glucose solution required. The 55% solutions would now need 27.5ml of the 1.0M glucose solution diluted up to 50ml with deionised water (22.5ml) and this would still be a 55% glucose solution. 7. Transfer the 100ml of the measuring cylinder to a 100ml beaker and label it appropriately. 8. Place it in the water bath. 9. Repeat the above procedure, increasing the amount of glucose each time accordingly (usually 5ml). Do this until all 21 concentrations have been made up. (0% 100%) Stand all labeled beakers in the water bath at 30o c. 10. Firstly, using the bakers yeast, weigh out 5 separate lots of 0.5g into weigh boats. Transfer each of the weigh boats contents into each of the 5 side armed test tubes, ensuring not to disturb the displacement measuring cylinders. ...read more.

Conclusion

Also, the addition of oxygen may have improved the results obtained as well. Yeast prefer to work aerobically, therefore, different results may have been obtained if oxygen was passed through the solution and subtracted from the final volume of gas collected. Obviously, the available apparatus was a problem here. When yeast respires anaerobically, they may produce different volumes of CO2 - a lower yield to when they respire aerobically. Although the water baths did keep the temperature steady within a few degrees Celsius, which was easier than using a Bunsen burner, they could never really keep the temperature constant which would have produced a much fairer test. One big improvement that could have been made to the experiment would have been to replicate each test, on each concentration of the glucose 3 times. If the mean result of these three tests were taken, it would have produced much more accurate results. Obviously the time it would have taken to do this would have made it virtually impossible to carry out. Finally, another problem, which may have accounted for anomalous results, is the idea that the mass of the yeast used each time (0.5g), may not have actually reflected the size of the population as some of the 0.5g of yeast may have in fact been dead to start with, making each test unfair. Anomalous results - These are highlighted on the graphs. All of the above factors may have accounted for the production of these freak results. Unless several repetitions were carried out to attempt to 'iron' out these results, it would be almost impossible to avoid them. Andrew Muir 01/05/07 1 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Exchange, Transport & Reproduction section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Exchange, Transport & Reproduction essays

  1. Marked by a teacher

    Biology coursework planning - the effect of lead chloride on the growth of cress ...

    5 star(s)

    the roots were very entangled and sometimes caused the shoots to break when trying to remove them from the medium. The growth of the shoots in the cotton wool may also have been inhibited if the shoots could not grow out and beyond the cotton wool.

  2. Marked by a teacher

    What is Type 1 diabetes

    3 star(s)

    Controlling diabetes and its possible complications Diabetes can be controlled through routine check-ups by your doctor or annual check-ups at the hospital on an outpatient basis, or both. The purpose of the controls is to check that treatment is progressing satisfactorily (routine check-ups)

  1. Peer reviewed

    The comparison of antibacterial properties of herbal products and standard antibiotics

    5 star(s)

    Thus meaning penicillin has minimal effect against gram negative bacteria, but more successful when in contact with gram positive, and by looking at the M.luteus results you can see this.

  2. Peer reviewed

    "An investigation into the Respiration of Carbohydrate Substrates by Yeast."

    5 star(s)

    There can be more than 3000 repeating units in a chain, joined by glycosidic bonds, forming many complicated structures, one being starch. Starch is a polymer of alpha glucose, where the hydroxyl group is below the ring, and is made up of 30% amylose and 70% amylopectin.

  1. The Effect of Different Substrates on the Rate of Respiration on Yeast (Saccharomyces cerevisiae).

    Fig 4 outlines the two processes. Aerobic When the yeast is mixed with sugar or glucose solution, it soon starts to respire. The yeast uses sugar and oxygen dissolved in the water to produce carbon dioxide, water and energy by aerobic respiration. Glucose is phosphorylated, eventually producing two molecules of pyruvate.

  2. Investigate the effect different concentrations of glucose in a yeast & Glucose solution has ...

    INPUT OUTPUT CONTROL VARIABLE Glucose Volume of CO2 Concentration of Yeast Stirring Temp Time pH How will each affect the experiment? In the next few lines I will explain each. pH - The pH will have to stay close to neutral (7)

  1. Rate of respiration in Yeast.

    Therefore I am confident that the experiment I conducted was a fair and accurate one. Graphs: Analysis of graph: The graphs show that the glucose had the greater number of bubbles formed. The averages for the two sugars also show that the glucose has a greater number of bubbles of formed.

  2. To find out the factors affecting the refractive index of liquid by using different ...

    Direct the laser pointer pointing towards the table. Put the container on a rack, with an A4 paper underneath the container. Draw a straight line of symmetry on the paper. Then adjust the light beam to make it shone on the line. Shone the beam and make a mark on the other side of the paper since I cannot move the container.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work