• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10

The rate ofrespiration in yeast and how it is affected by temperature.

Extracts from this document...


The rate of respiration in yeast and how it is affected by temperature Planning Introduction Yeast is a single celled, or unicellular, fungus made up mostly of protein. Once yeast is activated, it respires by secreting the enzyme zymase into the yeast, which acts on simple sugars such as glucose. This gives off carbon dioxide, energy and alcohol (such as ethanol) in anaerobic respiration or water, carbon dioxide and energy in aerobic respiration. The alcohol produced can be used to make wines and beers, and the carbon dioxide produced can be used in baking, as it gets trapped in the dough and causes it to rise. When the yeast respires, we say that respiration is occurring. Respiration is the process off getting energy from food. This occurs in every living cell. Yeast can respire both aerobically (with oxygen) and anaerobically (without oxygen). The equation for aerobic respiration is: Glucose + oxygen water + carbon dioxide + energy The equation for anaerobic respiration is: Glucose Alcohol + carbon dioxide + energy We are going to study the aerobic respiration of yeast. This is respiration with oxygen, as air containing oxygen will be present. This is an enzyme-controlled reaction. Enzymes only work up to a certain temperature, until they are denatured. This means that, in theory, the reaction will work best at certain conditions, but when the enzymes are denatured the reaction stops and is unable to go forward. Aim: The aim of my experiment is to discover if there is any correlation between rate of respiration of glucose by yeast and the temperature at which the reaction is taking place. Prediction: I predict that the rate of respiration of the yeast will increase as the temperature increases, up until a certain point where the enzyme used in this reaction is denatured. This is because at a certain temperature it becomes too hot for the enzymes to continue working, and once the temperature has reached this point the enzymes will never be able to work again - we say they have denatured. ...read more.


I placed the thin rubber tube on the end of the syringe. * I set up apparatus as shown in the diagram, making sure that no air is left in the smaller syringe - all of the air must be displaced by water or my results will be incorrect * I allowed 5 minutes for the mixture to equilibrate * Then I started the stop clock * While the experiment is taking place, I made sure that the water is kept at the desired temperature, and that all the apparatus was still in place * I stopped the stock clock after 5 minutes * I accurately measured the amount of air (carbon dioxide) that has displaced the water in the small syringe. I was careful not to measure the top of the meniscus, but the bottom. I made sure that an error of parallax is not created, by making sure that my eye was in line with the object. * I then recorded results and observations Safety Precautions When working with the higher temperatures such as 50 and 60 degrees Celsius, wear rubber gloves. This will prevent burns and pain caused by the hot water. Be careful not to drip water over any electrical appliances such as the kettle. Do not carry hot or boiling water around the classroom at any time: keep a beaker or kettle next to you if you need hot water at hand. Wear a lab-coat. Take care at all times when handling equipment. Any earlier work that helped my planning: We have studied the respiration of yeast during class, and most of this information can be found in our textbooks or else on the Internet (e.g. www.bbc.co.uk) or software programs (e.g. Microsoft Encarta) Obtaining Evidence The equipment that I will use will allow me to obtain precise results. There may be more accurate alternatives - such as using a digital thermometer. ...read more.


I do not think I have enough evidence to say the exact temperature at which enzymes denature. My results are not 100 % accurate because I know that the temp was not kept constant at all times, that the yeast suspension may have had some variance in glucose concentration (because other student may have dipped their syringes into the yeast suspension after dipping them into glucose solution). One way I could improve my method would be to redo the entire experiment again. This would minimize chance of error as well as making sure my results are correct. The more experiments I could repeat the better, although the only problem is the lack of time. Other ways to improve my experiment: I could make sure that my syringe was completely clean every time I dip it into either the glucose or yeast solution. Check that the rubber tube is completely secure on the syringe, allowing no air to escape. Check the apparatus before starting each experiment to make sure there were no mistakes in this area. Make sure I start my stop clock exactly as the experiment starts. It may be better to have an alarm on the stop clock so that it will ring at the exact time, thus it will be easier to take a reading at a correct time - as the alarm rings, instead of the slightly inaccurate method of looking at the stop clock until the correct time and then taking a reading. The temperature could be measured using a digital thermometer. This would give more precise readings. It would be easy to know when too add hot water, etc. and so will improve the reliability of the final results. Make sure no error of parallax occurs when measuring how much air was formed in the syringe. Do this by keeping the object and your eye in a straight line. Try to repeat the experiment as many times as possible, and making averages. Each time I repeat the experiment, my results will become more reliable. Luke Winter 11X Biology c/w Respiration of Yeast 2003 1/10 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Green Plants as Organisms 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 GCSE Green Plants as Organisms essays

  1. Investigating the Factors Affecting Respiration in Yeast.

    To keep the results precise, all the measurements will be measured to 3sf (three significant figures). To confirm that the findings are accurate, I will check through my biology textbooks and see if they agree with my results. My Prediction The respiration rate will go quite slowly when it is at 30 degrees.

  2. The effect temperature has on the rate of anaerobic respiration in yeast.

    even more and check if my scientific knowledge is correct This is because temperature effects the rate at which enzymes work, making them move and work faster on the substrate (in this case is sugar), because heat produces energy. Eventually when the surrounding of the enzymes get too hot the

  1. What is the effect on the rate of respiration of yeast cells with glucose ...

    (Biology Foundation 5.1.3 Enzymes). Table to show reasons for choice of apparatus Item What it is used for Reason for choice 100ml measuring cylinder To measure out appropriate volume of solution needed. It is easy to use and allows accurate measurements to be taken.

  2. Investigating respiration in aged yeast

    Risk assessment The apparatus and the method is relatively safe, but the only area of concern is that the most parts of the apparatus are made of glass, so I should be careful not to break any, or if this happens to remove the broken glasses with caution.

  1. An investigation of the factors that affect the rate of respiration in Yeast.

    After this I then came to the conclusion that I should only stay a few degrees below 37�C and a few degrees above it. I did this but there was not much difference in rate of reaction between each of these degrees and therefore the results would mostly be the same.

  2. In this experiment, I am going to investigate the effect of heat on the ...

    I will then count the number of bubbles that come out of the delivery tube per minute and I will do this for three minutes in total therefore collecting three results for each temperature. Once I collect all the results for 30�C, I will repeat exactly the same experiment with 22�C and then 40�C.

  1. Investigation into the Affect of Temperature on Yeast Activity.

    * The intensity that the glucose and yeast solution is shook at. This must remain constant at a gentle rate as a minor change in shaking intensity can significantly alter the rate at which bubbles are produced. * The independent variable in this investigation is the temperature of the glucose and yeast solution.

  2. An Investigation to Show the Effects of changing temperature in Yeast Respiration.

    This is called denaturing the enzyme, I predict that this will happen at 70 - 80 C. Plan First I will set up the apparatus as show above. I will add 1.5 grams of sugar to 25ml of water and dissolve it.

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