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

Biology AS Planning Exercise.

Extracts from this document...


AS Planning Exercise. Yeast cells anaerobically respire to produce CO2 and Ethanol. This process is referred to as fermentation. Thousands of enzymes catalyse this process. Yeast cells will die if their enzymes become denatured. High temperatures can bring about the denaturation of an enzyme. (Ref ?) Plan an investigation to find the lowest temperature that kills all the yeast cells in a suspension of either dried or fresh bakers yeast. ............................... To find the lowest temperature that will result in the yeast cells ceasing to respire I will mix glucose (C6H12O6) into a yeast suspension, add Methylene Blue and time how long it takes for the Methylene Blue to be reduced ie. go colourless (the longer it takes, the lesser respiratory activity occurring). Prediction. The temperature at which the yeast cells are killed will be 45�C. Explanation. Enzymes are globular proteins which denature (lose their tertiary structure) when exposed to a number of factors such as pH and high temperatures. ...read more.


Results. Volume of Yeast Suspension (cm3) Volume of Glucose Solution (cm3) Time taken for Methylene Blue to be reduced (s) 8 2 227 6 4 512 5 5 516 4 6 600+ I will use 8cm3 yeast suspension and 2cm3 glucose solution as my preliminary experiments showed these two volumes to be effective in achieving the shortest time in reducing the Methylene Blue. Factors Kept Constant. 1. Volume of glucose solution (2cm3) 2. Volume of yeast suspension (8cm3) 3. Concentration of glucose solution (10%) 4. Concentration of yeast suspension (10%) 5. Type of yeast Apparatus. Boiling Tubes Water Bath Thermometer Stop-Clock Yeast Suspension Glucose Solution Glass Rod Sticky Labels Tongs 5cm3 Syringe 10cm3 Syringe Methylene Blue Method. 1. Prepare the water bath at 30�C. 2. Place 8cm3 10% yeast suspension and 2cm3 10% glucose solution using a 10cm3 syringe (for the yeast suspension) and a 5cm3 syringe (for the glucose solution) into a boiling tube. 3. Add a drop of 1% Methylene Blue. 4. Stir with a glass rod. 5. ...read more.


2. Ensure that additional items of clothing & other obstructions are out of the way. 3. Take care to avoid spillage's by using tongs to place the test tubes into the water bath. After the experiment is finished leave 20 minutes before removing it. Wear gloves to protect your hands. Table of Results. Temperature (�C) Time Taken For Methylene Blue To Go Colourless (s). Average Value (s) Expt 1 Expt 2 Expt 3 30 35 40 45 50 55 60 Calculations. I will use the average time values to calculate the rate. Rate = 100/time Graph. 0 30 35 40 45 50 55 60 Temperature (�C) Interpretation of Results. After 45�C there will be a decline in the time taken for the Methylene Blue to go colourless. This will be shown on the graph by being the peak of the rate. Validity of Results. A fundamental part of this experiment is to time how long it takes for the Methylene Blue to lose its colour. However, this presents a problem as an individuals interpretation of when this occurs can vary, therefore affecting the results due to human error. ...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 temperature on the rate of respiration in yeast

    5 star(s)

    x1 Small beakers x1 Ice Not any volume suggested depending on the need. Lab coats x1 Safety goggles x1 Small syringes x1 \ 1.0ml Method: * Firstly I will put on all the safety equipment on such as lab coat and goggles.

  2. Marked by a teacher

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

    5 star(s)

    Some subjects also seemed rather confused, although the experiment was explained and even shown to them, signs of confusion and laxidasical approach could be seen. Further investigation into the factors that may influence reaction times is 'arousal' or state of attention, including muscular tension.

  1. Marked by a teacher

    Effect of nitrate concentration on the growth of Duckweeds

    5 star(s)

    The membrane of these plant cells contains scattered proteins, which in the root cells allow theuptake of nitrates and other essential nutrients. Proteins are vital components in a plants variety of metabolic pathways and processes. Proteins make up the molecular structure of DNA, RNA and host of other critical metabolic processes required for plant growth.

  2. Marked by a teacher

    'An investigation into the ability of two strains of the yeast Saccharomyces cerevisiae to ...

    4 star(s)

    This is a very significant increase, especially when it is compared against the statistics of the wine yeast, where only a comparatively marginal increase in respiration has occurred. Table 4 shows that the neutralisation requirement has changed from 6.32cm3 to 6.84cm3 of NaOH, a mere 8% increase by comparison.

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

    During the test we found that the biggest pH drop in the smallest amount of time was seen when we carried the test out at 37oC which is the body temperature. Therefore we disregarded doing our actual method with the other two temperatures of 50oC and 30oC as 37 proved

  2. An investigation into the distribution of adult and juvenile limpets on a rocky shoreline.

    Therefore l can reject the null hypothesis and determine that adult and juvenile limpets are occupying different shore heights. Only a small number of juvenile limpets choose to inhabit the upper shore in comparison to the middle and lower shore.

  1. out how different concentrations of the enzyme pectinase affect the degradation of the substrate ...

    may not vary from fruit to fruit and thus affect the volume of fruit juice obtained. * Distilled water must be used because tap water contains impurities, which could affect the permeability of the cell membrane in each different kind of fruit.

  2. Effects of exercise on tidal volume and breathing rate

    Even during forced ventilation the lungs will never be fully devoid of air this is known as the residual volume. To measure the vital capacity of the lungs the subject first breaths out to force as much air from the lungs.

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