• 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)

    A table to show the average length of shoot of cress seeds grown in different arrangements. Arrangement of cress seeds Average length of shoot of cress seeds (mm) Grid 1 47.3 Scatter 38.3 Grid 2 44.4 Note: All figures in the table are correct to 3 significant figures as per the Institute of Biology guidelines.

  2. Marked by a teacher

    What is Type 1 diabetes

    3 star(s)

    Some of the common traits in Type 2 diabetic patients are: family history of diabetes obesity increased blood pressure premature vascular problems such as heart attacks and stroke abnormal triglycerides (lipid or neutral fats) in the blood. How is diabetes treated?

  1. Peer reviewed

    The comparison of antibacterial properties of herbal products and standard antibiotics

    5 star(s)

    The gram staining procedure involves the use of crystal violet and gram's iodine solution to identify the difference in cell structure. In gram positive bacteria the cell wall consists mainly of polymer layers composed of peptidoglycan, which are all connected via amino acid bridges.

  2. 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.

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

    Height (h) (cm) Refractive index (�) (5 s.f.) 30 8.6 2.5 7.6 27.8 30.5 1.3207 40 8.6 2.5 7.6 27.8 30.5 1.3207 50 8.6 2.5 7.6 27.8 30.5 1.3207 This result is very close to the standard refractive index of pure water, which is 1.3333.

  2. Rate of respiration in Yeast.

    The line graph has a similar pattern for both the sugars on the first trial it goes up significantly and up to the fourth it dips down and on the fifth rises back up again. Conclusion: From my experiment I can conclude that that the glucose sugar made the yeast respire at a much faster rate.

  1. Investigation into the effects of different

    .This will be done in order to investigate if it was only the nutrients (glucose, maltose and starch) are the ones affecting the yeast growth, And it is to ensure that it is only the independent variable affecting the dependant variable.

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

    Heavy metals such as Zinc * Stirring * Volume of yeast + Concentration * Volume of glucose Some of these factors will be controlled while others will be changed, or measured. Underneath you will see a table of what will be done.

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