Biology HL
Biology HL
Sample Internal Assessment
Sample Internal Assessment
6/7
6/7
18 mins Read
18 mins Read
3,584 Words
3,584 Words
English
English
Free
Free

Effect of type of sugar on rate of cellular respiration in yeast

Table of content

Rationale

Being passionate about cooking and especially baking, I know the process of using yeast mixed with flour and sugar to make breads and cakes. Yeast are used in the process as they ferment complex carbohydrate units and release carbon dioxide which causes the bread to rise up. This process is aerobic in nature as oxygen is utilized in the process where yeast undergoes cellular respiration. During such process, yeast releases carbon dioxide and energy. The type of sugar used in such process plays a major role as the type of sugar is not same everywhere. From the industrial aspect, it is that the process is fast enough. The purpose of this investigation is to understand whether the type of sugar used has any effect on the rate of cellular respiration or not. The rate of such process can be monitored by quantitative measurement of the carbon dioxide evolved during the process. Thus, I decided to narrow down my Internal Assessment in Biology on the research question phrased below-

 

Does the rate of cellular respiration (measured in terms of amount of carbon dioxide evolved per min over an interval of 30 minutes) in yeast (Saccharomyces cerevisiae) depends on the type of sugar (sucrose, fructose and glucose) used?

Background information

Respiration in yeast

Yeasts are unicellular globular shaped fungi. They have the ability to produce energy on fermentation of carbohydrates through respiration. This can happen both is presence and absence of oxygen. The respiration that happens in presence of oxygen is aerobic respiration and the chemical equation is for that is as follows:

 

Glucose + Oxygen\(\rightarrow\) Carbon dioxide + Water + ATP (energy)

 

The same process is recognized as an anaerobic respiration when it happens in absence of oxygen and the equation is as follows:

 

Glucose\(\rightarrow\) Ethanol + Carbon dioxide + ATP (energy)

 

It must be noted that carbon dioxide is evolved as a by product in both aerobic and anaerobic respiration. Anaerobic respiration is also known as fermentation. As alcohol (ethanol) are produced during fermentation, this is also known as alcoholic fermentation. In both cases, energy is produced as ATP molecules. The amount of energy produced during aerobic respiration is much higher than that in anaerobic respiration.

 

The current investigation is focused on aerobic respiration which is a cellular process happening in yeast.

  • Nail IB Video
    Dr. Angela Jebailey

    Experienced IB Bio teacher with a 6.18 student avg, ready to help you nail that 7!

    Video Course

  • Stages of aerobic respiration in yeast

    Aerobic respiration in yeast follows a catabolic pathway comprising mainly of four different steps- Glycolysis, Link Reaction, Kreb’s cycle and chemiosmosis. The release of carbon dioxide from the cell wall happens during the last stage which is chemiosmosis. Due to combustion process happening inside the cell, the osmotic pressure is higher inside the cell which causes the carbon dioxide to be released out of the cell. The release of carbon dioxide from the cell wall during cellular respiration results in the formation of foam. Hence, the rate of respiration can be monitored by both measuring the rate at which carbon dioxide is evolved as well as the amount of foam produced.

     

    Yeast secretes a lot of enzyme during each and every step of the aerobic respiration. As enzymes gets denatured (loses their shape and cannot bind to the substrate) at high temperature, controlling temperature during this process is essential. The process is carried out at 40.0oC as that has been reported to be the optimum temperature of fermentation.

    Determination of rate of cellular respiration

    The amount of foam produced can be measured in terms of amount of Carbon dioxide at regular intervals of time and the values can be plotted against the time. The rate of the reaction can be determined from the gradient of such plots.

    Figure 1 - Determination Of Rate Of Cellular Respiration

    Literature review

    A literature review of a research article on the title1 - The effect of different sugars in the medium on carbon dioxide production in Saccharomyces cerevisiae by Jason Angustia, Maggie Chan, Deirdre Dinneen, Shamim Hortamani, Diane Mutabaruka reveals that the rate of cellular respiration is higher for glucose and fructose in comparison to sucrose. The level of CO2 produced was recorded as a function of time for four different types of sugars – glucose, maltose, fructose and sucrose. The image below2 is a snap shot of the data table of that research article in support of the statement written above.

    Figure 2 - Literature Review

    Hypothesis

  • Nail IB Video
    Dr. Angela Jebailey

    Experienced IB Bio teacher with a 6.18 student avg, ready to help you nail that 7!

    Video Course

  • Null hypothesis

    There is no correlation between the type of sugar used and the rate of cellular respiration.

    Alternate hypothesis

    There is a correlation between the type of sugar used and the rate of cellular respiration.

    Type of variable
    Variable
    Method of measure/ variation
    Independent
    Type of sugar used – Glucose, fructose and sucrose
    The same amount (in moles) of these sugars will be weighed and aqueous solution will be prepared.
    Dependent
    Rate of cellular respiration
    The amount of foam produced will be measured at regular intervals of time and the height of foam will be plotted against time. Rate of the reaction will be calculated from the gradient of the curves.
    Figure 3 - Table On Variables
    Controlled variable
    Why is it controlled?
    How is it controlled?
    Amount of sugar
    The rate of any reaction depends on the quantity of the reactant used. As sugar is the reactant in the process, the amount of sugar plays a role.
    Same amount of sugar (in terms of mole, 0.1 mole) will be used in all trials.
    Temperature
    Cellular respiration is an enzyme controlled process and thus the temperature at which the process is carried out is important. Moreover, it must be noted that at high temperature enzymes gets denatured and also reaction rate increases.
    The temperature was kept constant at 40.0oC as the enzyme involved in the process are reported to have optimum values at that temperature.
    Time interval
    The rate of cellular respiration is measured in terms of the amount of foam produced. This will depend on the time for which the sugar solution was in contact with the yeast.
    In all trials, the data was collected over an interval of 30 minutes at an interval of every 5 minutes.
    Surface area
    Cellular respiration is a biochemical process and thus surface area plays a role to control the rate of the reaction.
    All trials were performed in the same glass beaker of capacity 250cc.
    Amount of yeast
    The rate of respiration will depend on the number of cells in which it is occurring and thus will vary with the mass of the yeast taken.
    5.00 g of yeast was used in all trials.
    Figure 4 - Table On List Of Controlled Variables

    Materials required

    • Yeast
    • Glucose – 10.00 g
    • Sucrsoe – 10.00 g
    • Fructose – 10.00 g
    • Distilled water – 1000cc
    Apparatus
    Capacity
    Quantity
    Glass beaker
    250 cc
    1
    Glass rod
    NA
    1
    Digital mass balance
    Max:500.00 g
    1

    CO2

    gas sensor
    Max:1000 ppm
    1
    Watch glass
    NA
    1
    Volumetric flask
    100 cc
    3
    Spatula
    NA
    1
    Graduated measuring cylinder
    100 cc
    1
    Figure 5 - Table On Apparatus Required

    Safety precautions

    • Yeast is not a harmful organism but inhalation or direct ingestion is not recommended. Thus a physical barrier with the microorganism is essential to avoid any sort of cross contamination. Protective clothings like safety gloves, lab coats were used.
    • None of the materials used were ingested or exposed to skin. Eatables were not allowed inside the laboratory as the microorganism used might infect them.

    Ethical considerations

    The methodology adopted or the issue at which the investigation is focused on does not have any ethical issues.

    Procedure

  • Nail IB Video
    Dr. Angela Jebailey

    Experienced IB Bio teacher with a 6.18 student avg, ready to help you nail that 7!

    Video Course

  • Preparation of solutions

    18.00 ± 0.01 g (0.1 moles) of glucose was weighed on a watch glass using a digital mass balance. The weighed solid was transferred to a neat and dry 100 cc volumetric flask and dissolved in 100 cc distilled water.

     

    Similarly, aqueous solutions of sucrose and fructose were prepared by dissolving 34.2 g of sucrose and 18.0 g of fructose in 100 cc of distilled water.

    Determination of rate of cellular respiration

    • A 250 cc glass beaker was taken and filled with 50 cc of the glucose solution.
    • 5.00 ± 0.01 g of yeast was weighed on a watch glass using a digital mass balance and added to it.
    • The stop-watch was started.
    • The amount of CO2 produced was then measured after 5 minutes using a CO2 gas sensor.
    • The gas sensor was calibrated before use.
    • The measurement of CO2 produced was continued till 30 minutes at an interval of 5 minutes.
    • Steps 1-5 were repeated for four more times to collect data in five sets.
    • Steps 1-6 were repeated for other two solutions – sucrose and fructose.

    Qualitative observations

    •  The sugar solutions used were transparent and clear.
    • Addition of yeast to the sugar solution turned the solution turbid. 
    • With the progress of time, the solution turned more turbid and more foam were produced.
  • Nail IB Video
    Dr. Angela Jebailey

    Experienced IB Bio teacher with a 6.18 student avg, ready to help you nail that 7!

    Video Course

  • Data collection and processing

    Figure 6 - Table On Measurement Of Height Of Foam For Glucose

    Sample calculation

    Average amount of CO2 evolved in ppm ( for 300.00 s) =\(\frac{300+310+300+320+330}{5}\)= 312.00

     

    Standard deviation = \(\frac{(300-312)^2+(310-312)^2+(300-312)^2+(320-312)^2+(330-312)^2}{5}\) = 13.04

    Figure 7 - Amount Of CO2 In Ppm Against Time Or Glucose

    The above graph is a scattered plot of amount of CO2 evolved in ppm against time in seconds. The error bars are plotted using MS-Excel. A linear trend line has been derived using MS-Excel. The equation follows the format y=mx + c ; where y represents the amount of CO2 evolved in ppm and x represents the time in seconds.

     

    The gradient of the equation is represented as m and it represents the rate of the reaction in ppm/min. 

     

    Equation of linear trend line: y = 0.149 x + 256.61

     

    Rate of fermentation of glucose = 0.149 ppm/min

     

    It means that during the fermentation of glucose, 0.149 ppm of CO2 is evolved per minute on an average.

    Figure 8 - Table On Measurement Of Height Of Foam For Fructose
    Figure 9 - Amount Of

    CO2

    In Ppm Against Time In Seconds For Fermentation Of Fructose

    The above graph is a scattered plot of amount of CO2 evolved in ppm against time in seconds. The error bars are plotted using MS-Excel. A linear trend line has been derived using MS-Excel. The equation follows the format y=mx + c ; where y represents the amount of CO2 evolved in ppm and x represents the time in seconds.

     

    The gradient of the equation is represented as m and it represents the rate of the reaction in ppm/min.

     

    Equation of linear trend line: y = 0.073 x + 291.27

     

    Rate of fermentation of fructose = 0.073 ppm/min

     

    It means that during the fermentation of fructose, 0.073 ppm of CO2 is evolved per minute on an average.

    Figure 10 - Table On Measurement Of Height Of Foam For Sucrose
    Figure 11 - Amount Of

    CO2

    In ppm Against Time In Minutes For Fermentation Of Sucrose

    The above graph is a scattered plot of amount of CO2 evolved in ppm against time in seconds. The error bars are plotted using MS-Excel. A linear trend line has been derived using MS-Excel. The equation follows the format y=mx + c ; where y represents the amount of CO2 evolved in ppm and x represents the time in seconds.

     

    The gradient of the equation is represented as m and it represents the rate of the reaction in ppm/min.

     

    Equation of linear trend line: y = 0.034 x + 294.72

     

    Rate of fermentation of fructose = 0.034 ppm/min

     

    It means that during the fermentation of fructose, 0.034 ppm of CO2 is evolved per minute on an average.

    Analysis

    Figure 12 - Comparison Of Rates Of Cellular Respiration Of Yeast For Different Types Of Sugar

    Graph-4 is a bar graph to compare the rates of cellular respiration in yeast for different types of sugar. The height of the bars represents the rates of cellular respiration as it is plotted along the y axes while the type of sugar is plotted along the x axes. As it is clearly visible in the graph, the rate of cellular respiration is maximum for glucose – 0.149 ppm/.min and minimum for sucrose (0.034 ppm/min).

    Scientific justification

    Cellular respiration is a biochemical process where glucose undergoes combustion to produce carbon dioxide and release energy in the form of ATP molecules along with formation of H2O.

     

    Glucose + Oxygen \(\rightarrow\) Carbon dioxide + Water + ATP

     

    Experimental studies has revealed3 that the bottleneck of this process is related to uptake of sugar by the microorganism and yeast can consume the nutrient only in the form of glucose.

     

    Glucose is a simple carbohydrate or a monosaccharide to be specific. Any other carbohydrate used has to be first hydrolyzed to form glucose before cellular respiration occurs. Fructose is also a monosaccharide. It can be converted to glucose by the enzyme isomerase as glucose and fructose are isomers of each other. Thus, in case of glucose, the substrate is directly available while in case of fructose, first the raw material has to undergo isomerization to glucose and then the reaction begins. This clearly explains why the rate of cellular respiration is faster with glucose and slower with fructose.

     

    Sucrose is a disaccharide. It is formed by joining two simple sugars – glucose and fructose through glycosidic linkages. Hence, first sucrose has to undergo hydrolysis to form glucose and fructose and then the cellular respiration begins as the substrate for this process is glucose and not fructose. Thus, during the case of sucrose, there are two steps that must happen before the cellular respiration begins- hydrolysis of sucrose to glucose and fructose and then isomerization of fructose to glucose. This delays the process of cellular respiration and thus the rate is lowest in case of sucrose.

     

    Thus it is clear that the rate of cellular respiration is faster with mono-saccharides –glucose and fructose than disaccharides –sucrose.

    Statistical analysis

    The basic aim of the investigation is to compare the rates of cellular respiration for different type of sugar units. The sugar units chosen for this investigation are glucose, fructose and sucrose. Glucose and fructose are mono- saccharides while sucrose is a disaccharide. An independent T test will be performed with glucose (a mono saccharide ) and sucrose (a disaccharide). The purpose of the T test is to understand if the type of sugar – monosaccharide or disaccharide do have an effect on the rate of cellular respiration or not.

     

    Null hypothesis

    Rate of cellular respiration in yeast has no correlation with the type of sugar used-monosaccharide or disaccharide.

     

    Alternate hypothesis

    There is a significant statistical difference between the rates of cellular respiration between the two different types of sugar units used-monosaccharides or disaccharides.

  • Nail IB Video
    Dr. Angela Jebailey

    Experienced IB Bio teacher with a 6.18 student avg, ready to help you nail that 7!

    Video Course

  • Figure 13 - Table On Independent T Tests

    Degrees of freedom = (6 + 6) – 1 = 11

     

    Critical value of t = 2.201

     

    Calculated t value = \(\frac{413.13-330.50}{\sqrt({}\frac{(84.20)^2}{6}+\frac{(19.18)^2}{6}}\)= 2.343

     

    Thus it is observed that the calculated value of t (2.343) is greater than the critical value of t (2.201). Hence, the null hypothesis is rejected and the alternate hypothesis is accepted.

     

    Hence, we can conclude that the rate of cellular respiration in yeast depends on the type of sugar unit used.

    Conclusion

    The basic aim of the investigation was to answer the research question-

     

    Does the rate of cellular respiration (measured in terms of amount of carbon dioxide evolved per min over an interval of 30 minutes) in yeast (Saccharomyces cerevisiae) depends on the type of sugar (sucrose, fructose and glucose) used?

    • As indicated in Graph-4, the rate of cellular respiration in yeast depends on the type of sugar used. The rate of cellular respiration is found to be maximum for glucose (0.149 ppm/min) and least for sucrose (0.034 ppm/min). The rate for fructose is intermediate lower than glucose and higher than sucrose. In general, it can be claimed that the rate of cellular respiration is higher for monosaccharides (glucose, fructose) than disaccharides (sucrose).
    • The qualitative observations noted are also in support of the conclusion made. It was observed that the rate of formation of foam was maximum for glucose and minimum for sucrose.
    • To investigate further the dependence of rate of cellular respiration on the type of sugar, an independent T test was conducted which indicates that there is a significant difference between the rates of cellular respiration in monosaccharides and disaccharides. Thus, the null hypothesis has been rejected and the alternate hypothesis has been accepted.
    • The magnitude of correlation coefficient (R2 ) has been determined in Graph-1, Graph-2 and Graph-3 where the amount of CO2 evolved in ppm has been plotted as a function of time. The values of R2 are 0.9874 (for glucose), 0.9983 (for fructose) and 0.9944 (for sucrose). These values confirms that there is a strong positive correlation between the amount of CO2 evolved (an indicator of rate of cellular respiration) and time. It means that with the progress of time, the cellular respiration becomes faster.
  • Nail IB Video
    Dr. Angela Jebailey

    Experienced IB Bio teacher with a 6.18 student avg, ready to help you nail that 7!

    Video Course

  • Evaluation

    Strengths

    • The values of standard deviation has been calculated in each data tables and the values indicates a close agreement between all the trial values collected which means that there is a huge precision in the data collection.
    • To support the claims made, the processed data was used in inferential statistics. An independent T test has been conducted to evaluate the hypothesis instead of simply relying on data processing.
    • The procedure adopted does not require any complex setting and can be easily performed in a school laboratory set up.
    • The focus of the investigation conducted has an industrial point of view as the choice of right sugar in making of breads or alcohol is important to fasten the process.

    Limitations

  • Nail IB Video
    Dr. Angela Jebailey

    Experienced IB Bio teacher with a 6.18 student avg, ready to help you nail that 7!

    Video Course

  • Random error

    There are multiple sources of random error in the experiment. These includes – uncertainty of apparatus used, lose of mass while preparing the solutions as the solid may not have been transferred completely. Adequate measures were taken to minimize the random error incurred because of these. Precise apparatus was used wherever possible like using a volumetric flask instead of a glass beaker to prepare the solutions. The solid was transferred using a funnel instead of adding it simply to the volumetric flask.

    Methodological limitations

    Although a CO2 gas sensor has been used to measure the CO2 levels in ppm, it must be noted that here sensors cannot be used to measure the amount of dissolved CO2. Some of the CO2 produced out of cellular respiration might get dissolved in the water and would thus not get detected or measured by the sensor. Moreover, the sensor will also take into account the level of CO2 in the atmosphere. To correct this, the amount of CO2 in the reaction site must be determined using the sensor prior to the investigation and this value must be subtracted from all the readings taken so that we measure only the CO2 produced out of cellular respiration.

    Systematic error

    Two electronic measuring devices have been used in the investigation- digital mass balance and the gas sensor. Both of these instruments can have zero error. To compensate this, the instruments must be calibrated before use using standard methods. If we observe Graph-1, Graph-2 and Graph-3, the linear trend line in anyone of them do not pass through the origin which confirms that this systematic error has interfered with the data collected and has thus reduced the accuracy of the results concluded.

  • Nail IB Video
    Dr. Angela Jebailey

    Experienced IB Bio teacher with a 6.18 student avg, ready to help you nail that 7!

    Video Course

  • Extension

    I would like to repeat the same investigation by changing two other conditions – temperature and amount of yeast. I would like to perform the experiment using a water bath and vary the temperature. At each temperature, I would measure the amount of CO2 evolved in ppm using the gas sensor at regular intervals of time. Then, the amount of CO2 evolved can be plotted against time to find the rate from the gradient of the curve. Thus, we can determine the rate of the process at various levels of temperature. This can enable us to understand the correlation between temperature and the rate of cellular respiration in yeast.

    References

    Cason, D. T., and Reid, G. C. 1987. On the differing rates of fructose and glucose utilization in Saccharomyces cerevisiae. Journal of the institute of brewing, 93 (1): 23-25.

     

    D’Amore, T., Russell, I., and Stewart, G. 1989. Sugar utilization by yeast during fermentation. Journal of Industrial Microbiology, 4 (4): 315-324.

     

    De La Fuente, G., and Sols, A. 1962. Transport of sugars in yeasts: II. Mechanisms of utilization of disaccharides and related glycosides. Biochimica et Biophysica Acta, 56: 49-62.

     

    Fugelsang, K. C. 2007. Wine microbiology: Practical applications and procedures.

     

    Chapter 8: Fermentation and post-fermentation processing. pp. 115-138. New York, NY: Springer.

     

    Jiang, H., Medintz, I., Zhang, B., and Michels, C. A. 2000. Metabolic Signals Trigger Glucose-Induced Inactivation of Maltose Permease in Saccharomyces. Journal of Bacteriology, 182 (3): 647-654.

     

    Lagunas, R. 1993. Sugar transport in Saccharomyces cerevisiae. FEMS Microbiology Letters, 104 (3): 229-242.

     

    Oliver, S. G. 1997. Yeast as a navigational aid in genome analysis. Microbiology, 143: 1483-1487.

     

    Pronk, J., Steensmays, Y. and Van Dijkent, J. 1996. Pyruvate metabolism in Saccharomyces cerevisiae. Yeast, 12: 1607-1633.

  • Nail IB Video
    Dr. Angela Jebailey

    Experienced IB Bio teacher with a 6.18 student avg, ready to help you nail that 7!

    Video Course