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

the effect of ethanol on the rate of anaerobic respiration

Extracts from this document...


The effect of ethanol on the rate of anaerobic respiration of glucose by yeast Aim: This is an experiment to investigate the six different ethanol concentrations on the time for the mixture containing glucose, yeast, ethanol an alkaline phenolphthalein to decolourise. Background theory: Saccharomyces cerevisiae is a species of budding yeast. It is perhaps the most useful yeast owing to its use since ancient times in baking and brewing. It is believed that it was originally isolated from the skins of grapes (one can see the yeast as a component of the thin white film on the skins of some dark-colored fruits such as plums; it exists among the waxes of the cuticle). Glucose molecules contain energy. The energy in glucose originally came from sunlight which was captured by chlorophyll molecules and used to make glucose in photosynthesis. If glucose is placed in oxygen and set alight, it burns vigorously. Large amounts of heat energy are released as the glucose molecules combine with oxygen to form carbon dioxide and water, and the energy from the glucose is rapidly transferred to heat energy. As this oxygen comes from the air, the process is called aerobic respiration. When oxygen isn't available, oxidative phosphorylation and the Krebs cycle cannot take place. This is also true in organisms or cells which do not contain the machinery to carry these out. In these circumstances, respiration takes place without oxygen- anaerobic respiration. ...read more.


sugar-yeast mixture when dropping out of the end of the capillary tube Accurate Stop clock To time the start of the reaction and the time intervals Accurate and easy to handle Goggles For eye protection The only way to protect the eyes Water bath To warm up the test tubes and increase the rate of respiration Easy to handle and low hazard Absolute ethanol It is the substrate It is easily available Alkaline phenolphthalein indicator To see the colour change Easily produced and harmless Distilled water To dilute the concentration of ethanol It is harmless and easily available Beaker Contains solutions Easy to use and is able to contain large amount of solution Fair test: All of these variables (including the controlled variables) will need to be controlled by me, and to be kept the same throughout the experiment in order to keep it fair and to get as accurate results as possible. The independent variable, in this experiment the concentration of ethanol, has to be changed other than that all the factors have to stay the same throughout the whole experiment. Variables: - Independent variable: the different concentrations of ethanol - Dependent variable will be the time taken for the mixture to decolourise Table to show the variables that must be controlled: Variable Why it must be controlled How it will be controlled Temperature of yeast and sugar and sugar-yeast-ethanol-phenolphthalein mixture If you increase the temperature you increase the rate of reaction. ...read more.


They could be a result of putting the yeast into the mixture not into the test tube last and the reaction would have started already. We could not put the yeast into all test tubes, which were in the water bath, at the same time and as a result our time in minutes is not as accurate as it could be. Further we had to make sure that the phenolphthalein was mixed throughout the whole test tube. A table to show some possible effects of limitations on the method limitation Error that may have resulted from the limitation Rank order of limitation with qualification Suggested improvement Justification for improvement Reading off the syringe falsely Incorrect results 4 Ask partner to have a look as well and read off at eye level The results would be more accurate Not stirring the yeast and sugar-ethanol-phenolphthalein-yeast mixture before using it Different enzyme concentrations in the yeast resulting in unreliable measurements 2 Make a list, ticking that you stirred the mixture every time before using There would be one enzyme concentration of yeast only No constant temperature Incorrect results 3 Keep temperature constant with using an electric radiator Temperature is a controlled variable and has to stay constant otherwise the rates of reaction will be faster Not being able to put the yeast into the sugar-ethanol-phenolphthalein mixtures at the same time Incorrect results 1 Doing on test tube at a time Yeast is the source of the enzyme. When it is put at different times into the test tube the time taken to decolourise will be different. ...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 Energy, Respiration & the Environment 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 Energy, Respiration & the Environment essays

  1. Marked by a teacher

    Effect of Anaerobic Respiration On Yeast

    5 star(s)

    There are many factors in which enzymes can be effected by environment however, such factors which can inhibit and in fact stop the enzyme catalyzed reactions from occurring. These factors therefore have an effect on the metabolic pathways involved in anaerobic respiration.

  2. Marked by a teacher

    effect of temperature on the rate of respiration in yeast

    5 star(s)

    This prevents the enzyme from reacting with its normal substrate. Therefore no product made. Competitive inhibition is reversible and can be overcome by increasing the amount of substrate on which the enzyme works. Non competitive inhibitors: Competitive Inhibition interferes with enzyme activity by "binding" permanently to the enzyme therefore it

  1. Marked by a teacher

    An investigation into the effect of different sugars on respiration in yeast.

    5 star(s)

    Only a small percent result in a reaction. This is due to the energy barrier to overcome. Only particles with enough energy to overcome the barrier will react after colliding. The minimum energy that a particle must have to overcome the barrier is called the activation energy.

  2. Marked by a teacher

    Effect of nitrate concentration on the growth of Duckweeds

    5 star(s)

    Nitrogen also stimulates the growth of roots, which enables efficient uptake of all other nutrients. Amino acids are made in the root tips and carried to growing areas in the plant to make proteins. From the table that contains all the results pooled from my class, I will use the results to consider the hypothesis made earlier on.

  1. Marked by a teacher

    Fighter Pilot A Statistical Analysis of Reaction time and its Correlation with Dominant ...

    5 star(s)

    Subject Dropping Distances (cm) Attempt 1 Attempt 2 Attempt 3 Attempt 1 Attempt 2 Attempt 3 1 29 45 31 31 46 41 40 2 51 35 33 32 66 30 19 3 61 32 26 33 26 28 34 4 29 25 46 34 47 34 31 5 50 21 20 35 31

  2. What effect does substrate have on respiration in yeast?

    Glycolysis happens in the cytoplasm where the monosaccharide is first phosphorylated to triose phosphate (TP), which also known as GALP. It is then oxidised to GP and then finally converted to pyruvate. GALP, GP and pyruvate are all three carbon compounds so for each monosaccharide two of these compounds are formed.

  1. the effect of bile concentration on the activity of the enzyme lipase during the ...

    because it increases the kinetic energy of the molecules therefore they will be more successful collision between the enzyme and the substrate I will carry all the experiments in a water bath so to keep the temperature constant and monitor it with a thermometer Volume and concentration of lipase The

  2. An investigation into the effects of temperature on the rate of anaerobic respiration of ...

    Glucose --> ethanol + carbon dioxide +energy C6H12O6 + 6O2--> 6CO2 + 6H2O The Kinetic theory states that, with an increase in temperature, the rate of reactions will increase. This is due to the increase of speed of the particles, brought about by the extra energy given to them by heat.

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