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

The Effect of Substrate Concentrationon the Rate of Yeast Fermentation

Extracts from this document...


GCSE Assessment - The Effect of Substrate Concentration on the Rate of Yeast Fermentation The aim of this investigation is to discover how the concentration of sugar affects the rate of fermentation by yeast cells. Fermentation is an anaerobic process and can be represented by the following equation. (enzymes in yeast) glucose � ethanol + carbon dioxide + a little energy C6H12O6 � C2H5OH + CO2 + a little energy Results These are the results gained for my experiment: Sugar Concentration 0% 2.5% 5% 7.5% 10% Initial Gas (mm) 8 8 9 9 11 Increase 3 mins 8 9 10 9 13 Increase 6 mins 8 9 10 10 16 Increase 9 mins 8 9 11 11 21 Increase 12 mins 8 9 11 11 27 Increase 15 mins 8 9 11 12 32 Increase 18 mins 8 9 11 12 41 Increase 21 mins 8 9 11 12 55 Rate mm of gas per min 0 0.1 0.2 0.2 2.1 These are the results gained from the whole class: NAME 5Z2 - PHR 0% 2.50% 5% 7.50% 10% Clark 0.24 0.38 0.52 1 3.42 Cooper 0.14 0.2 0.24 0.29 2.14 Dagnell 0.19 0.38 0.33 0.48 2.62 Davies 0.38 ...read more.


Molecules are in a state of a motion and therefore collide. The more collisions that take place the faster the rate of fermentation. If the concentration is high, the number of glucose molecules is abundant, therefore the probability that the enzymes (in yeast) come into contact with these molecules is high. This in turn increases the rate of fermentation. If the concentration is low, however, the number of glucose molecules is less and therefore the rate of fermentation decreases. The conversion of glucose to carbon dioxide and ethanol takes place in the active site of the enzyme. Enzymes are protein chains of amino acids. Their molecules are very precise three-dimensional shapes. The shape includes a 'dent' which is exactly the right size and shape for a molecule of the enzyme's substrate (in this case glucose) to fit into. This 'dent' is called the active site. When the glucose molecule slots into the active site, the enzyme changes it, pulling it out of shape and making it split into product molecules. The product molecules (in this case carbon dioxide and ethanol) ...read more.


When carbon dioxide is produced some of it may dissolve into the solution and does not appear as gas, this again may cause errors. Human error also adds to the problem of inaccurate readings. As one of the products is ethanol, it can intoxicate some of the yeast cells which would die. Also, as fermentation takes place the sugar and yeast gets less and results produced may not be reliable. Therefore the procedure could have been altered in order to produce accurate results. During the experiment, there was a lack of control of other variables, such as temperature. Also, the yeast solution (before it is given to us) may not be well shaken, which leaves an unbalanced number of yeast cells. The experiment could be improved in several ways. In order to control temperature, a water bath could be used to keep a constant temperature. The test tubes could be substituted for ones which have a scale down the side, in order to improve readings of carbon dioxide. Also, more sugar concentrations could be used to give a wider range of results. For example, the following concentration could be used instead: 0%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18% and 20%. This would produce more accurate results. Abdul Raja 5L ...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 Molecules & Cells 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 Molecules & Cells essays

  1. Marked by a teacher

    The Effect Of Temperature on the Respiration Of Yeast.

    5 star(s)

    Once I have done this I will add an enzyme inhibitor called Urethane or Cyanide to my TTC-Yeast mixture to denature all of the enzymes. Once I have done this I will put it in a separate test tube and dilute it with a constant amount of distilled water to

  2. Investigation to find the effect of glucose concentration on fermentation of yeast.

    Concentrations using ratios This enables me to easily gain highly accurate dilutions of my glucose solution because it to eliminates human error due to taking measurements beyond the accuracy of the measuring vessels or the human eye or using several measuring vessels.

  1. The investigation to find the effect of glucose concentration on fermentation of yeast.

    produced I used phenolphthalein to see the color change as an alternative. This was found to be more accurate as I could see the colour change-taking place, and practically it was easier to set up. * It was found that the predictions on the rate at which the substrates were respired were correct.

  2. The aim of this investigation is to find out how concentration of glucose affects ...

    very simple to set up and perform and is therefore feasible in the timeframe that I have. It is easily repeatable so I can gain a lot of data that is close to a hypothesis. This method is also very safe and has been known to produce good results in the past.

  1. Affect of sucrose concentration on the rate of respiration.

    I have chosen to repeat the experiment 3 times because it therefore allows me to calculate an average time. This will ensure that there are no abnormal results and it will increase accuracy. The amount of yeast is crucial, more yeast means more sucrose will be respired and more products created.

  2. Investigating the Effect of Temperature on the Fermentation of Yeast

    (this will be covered in more depth in the prediction) The increase in temperature will also increase the pressure. Variables Variable Effect Control Temperature Cells will respire quicker in a warm environment than those in a cold one. Independent variable - heated water at different temperatures Volume of water in

  1. Investigation into the Effect of Temperature on the Rate of Fermentation by Yeast.

    Also, the temperatures that the fermentation takes place at will have to be the same, because temperature, as shown above, has a very important affect on the rate of reaction. The test tubes and equipment will need to be clean, so that no microbes are present to interfere with the experiment.

  2. Investigating the Effect of Temperature on Rate of Respiration in Yeast

    [Biology 2 book]} Enzymes are also present in respiration. They are in the form of dehydrogenase enzymes, decarboxylase enzymes and ATP synthetase enzymes. ATP synthetase enzymes are used in the synthesis of ATP from ADP. ATP synthetase is a protein that spans the phospholipids bi-layer.

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