enzyme liver catalase hydrogen peroxide

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The Results Part C of Enzyme Experiment

Carmen Muir | AISHK | 2012

The Results Carmen Muir

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Results

Table 1: Results Table of bubble height (mL) with dif ferent percentages (%)

Height in mL Trial 1 Trial 2 Trial 3 Average Control

(No Liver)

S.D (mLs-

1)

Reaction Rate (mLs-1)

1% 0 0 0 0 0 0 0 2% 15 35 \ 25 0 10 0.5 3% 0 0 0 0 0 0 0 5% 0.1 0.1 0.1 0.1 0 0 0 7% 20 30 25 25 0 4.08 0.5


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Table 2: Observation Table of Trials with Liver and Hydrogen Peroxide (mL) Observations Photos Control No reaction occurred when detergent

was added to the Hydrogen Peroxide and swirled. Note: This experiment was done without the addition of liver.

1% No reaction occurred when liver was

added to the Hydrogen Peroxide and detergent. The small amount of foam seen in the picture was already present prior to adding the liver.

2% A large reaction occurred when the

liver was added to the 2% Hydrogen Peroxide and detergent. The picture to the right dictates that the reaction was on such a large scale that a different sized measuring cylinder was required. Note: The level of reaction was declared abnormal due to the extreme reaction despite its low concentration. Make comparisons with the 7 % trials.


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3 % No reaction occurred when the liver was added to the Hydrogen Peroxide and detergent. Note: Hydrogen Peroxide used was found to be older and therefore, less reaction

5% No reaction occurred when the liver

was added to the Hydrogen Peroxide and detergent. Note: Hydrogen Peroxide used was found to be older and therefore, resulted with less of a reaction.

7% A reaction occurred when the liver

was added to the Hydrogen Peroxide and detergent.


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Table 3: Validity and Reliabi l i ty Assessment Issues – Validity – Reliabi l i ty

Issues Validity Reliabi l i ty Liver Size Extreme care is to be taken

when cutting the liver cubes with the scalpel. Each cube should be weighed to keep the size consistent. Continue this process of weighing and cutting until each cube is roughly the same as each other.

The liver sizes affect the reaction of catalysing in the experiment, as a large difference of surface areas between each individual cube would affect the reaction rate. For example, a larger surface area would have more active sites and therefore, result with a bigger reaction and vice-versa with

0

0.1

0.2

0.3

0.4

0.5

0.6

0% 2% 4% 6% 8%

Rate of Reaction (mLs

-‐1)

Concentration of Hydrogen Peroxide (%)

Graph 1: Rate of Reaction of Liver (mLs-‐1) in Hydrogen Peroxide (%)

Linear (Linear Line of Best Fit)

0

2

4

6

8

10

12

0% 2% 4% 6% 8%

Rate of Reaction (%

)

Hydroen Peroxide Concentrations (%)

Graph 2: Standard Deviation of Liver (mLs-‐1) in Hydrogen Peroxide (%)

Linear (Linear Line of Best Fit)


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a smaller sized slice of liver. Measurement of liquids The substrate, which is the

Hydrogen Peroxide, would be measured in a measuring cylinder to try and use a similar amount of liquid for each trial. Distilled water that is being used to dilute the Hydrogen Peroxide will also be used to measure out the amount for each trial.

Getting accurate measurement in regards to diluting the Hydrogen Peroxide could affect the experiment where the amount of substrates for the enzymes to react to would be dissimilar to other trials.

Cleanliness of glass Glass is to be cleaned thoroughly so optimum vision can be obtained. This is to be achieved by only using clear glasses (unmarked) and being sure that all grime is removed from the glass surface.

An error can be made if it is unclear what the measurement is. This can lead to a compromise of the experiment as the readings are inaccurate and should be disregarded if this issue occurs.

Contamination of liver Liver should be handled with two sets of forceps. One to come in contact with the untouched liver, and one to be used when removing liver from the measuring cylinder.

To minimise the risk of cross contaminating the liver samples should residue of Hydrogen Peroxide transfer to another trial and compromise it.

Timing When timing for the reaction rate, attention must be paid to prevent recording data that is over or under time.

Time period must be kept uniform so there is consistency for all trials.

Discussion Aim, Hypothesis and Method The aim of the experiment was to investigate the effect of different concentrations (1%, 2%, 3%, 5% and 7%) of Hydrogen Peroxide on the height of bubbles produced when fresh liver is added through a chemical reaction process called catalysing. It was hypothesised that the highest concentration, in this case, 7%, would result with the quickest rate of reaction as it provided more substrates for the enzymes in the liver to react with. In relation to this, it was hypothesised that the lowest concentration (1%) would result with the slowest rate of reaction. The experiment was carried out through a process where each concentration was trialled three times to maximised validity and gain an average. 10 mL of Hydrogen Peroxide was added to three measuring cylinders, followed by two drops of detergent. Finally, the liver was added and a thirty seconds timer was started. At the end of the thirty seconds period, the height of the bubbles was measured and


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recorded. Results were averaged, and standard deviation and reaction rate was calculated. A control was used where no liver was added to the experiment for comparison with the trials where liver was added. Findings There were several inconsistencies present in the experiment that were not expected, the most prominent being the lack of a reaction with the 3% and 5% concentrations where the average was 0 (refer to Table 1). The secondary issue was the reaction of the 2% concentration where there was a considerably high average of 25mm (taken from two trials). The first trial was not measured as the level of reaction caused the bubbles to overflow (refer to Table 2: 2%). The presence of a O result was found to be related to the fact that the concentration batches for 3% and 5% were older and yielded less of a reaction than expected. The most accurate results were the 1% concentration and the 7% concentration where the 1% had an expected average result of 0mm and the 7% had a much higher average of 25mm (refer to Table 1). Mirroring this is the reaction rate where 1% had 0 mLs-1 and 7% had a reaction rate of 0.5 mLs-1. 2% shared the same reaction rate as the 7%, while 3% and 5% resulted with 0 mLs-1 (refer to Table 1). The standard deviation was a 0 for concentrations 1%, 3% (both all averaged 0) and 5% (all averaged 0.1). 2% and 7% were the only concentrations with evident deviations with 2% having a deviation of 10 and 7% having a deviation of 4.08 (refer to Table 1). Identifying apparent trends in the results were difficult as results were affected by the concentrations that were not producing expected results, primarily 3% and 5%. There was a slow increasing gradient in relation to reaction rate which was mainly a result of the 0.5 mLs-1 increase with the 7% concentration in comparison to the 0 mLs-1 with the 1% concentration (refer to Table 2: 1% and 7% and Graph 1). Standard deviation had a negative gradient as there was a large deviation with the 2% concentration but a marginally smaller deviation with the 7% (refer to Table 1 and Graph 2). The Standard Deviation was 0 for all trials except 2% and 7%. 2% had a standard deviation of 10 while 7% has a standard deviation of 4.08 (refer to Table 1). The high level of deviation for 2% was due to the 20mL difference between Trial 1 and Trial 2. 2% concentration had an unexpected high-level reaction where a Trial was exempted from the final results. This could have also affected the large standard deviation. 7% had a much smaller standard deviation as each trial had results that, numerically, were closer together. Research In relation to the research conducted prior to the experiment, the hypothesis was based on the assumption that a higher concentration would produce a higher reaction rate and average as there was more substrates to react with the enzymes. This was only evident with the highest concentration where it showed evidence of an increased average and reaction rate in comparison to the lowest concentration. In contrast, the results recorded with the 2%, 3% and 5% were unexpected as research suggested that there would be an increase of average and reaction rate parallel to the increase of concentration.


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In reference to the journal article: The Decomposition of Hydrogen Peroxide by Liver Catalase written by John Williams (1928), a conclusion is drawn from study of the effects of Hydrogen Peroxide concentrations on liver catalase. An excerpt from the journal states:

The velocity of decomposition of hydrogen peroxide is proportional to the concentration of catalase

The remark supports the hypothesis where the velocity (rate of reaction) of decomposition is affected by the concentration of catalase where a larger concentration of catalase would result in a larger reaction while a smaller concentration of catalase would result in a smaller reaction. Problems The most evident problem found with the experiment was the unexpected lack of reaction for the 3% and 5% concentrations. In reference to the research, and observations of other experiments that repeated the experiment with a different batch of the same concentrations, it was established that a reaction should have occurred with these two concentrations. An appropriate solution for this issue would be to repeat the experiment with a different batch of the same concentrations in order to gain accurate results. This was not done because there was the assumption that there would be enough data to support the hypothesis. The results that were affected was found to be the reaction rate where there was ‘0’ results (refer to Table 1 and Graph 1). It affected the experiment overall as there was no clear gradient found that could assist in making a concise, concluding remark of whether or not the experiment supported or disproved the hypothesis. Another problem identified was the obvious overreaction of the 2% concentration. One trial was botched as the unexpectedly strong reaction caused the bubbles to overflow, rendering the trial unusable. The solution to this problem was to use a bigger measuring cylinder, and furthermore, to repeat the trial in order to gain the third trial result.

Conclusion The aim of the experiment was to investigate the effect of different Hydrogen Peroxide concentrations when fresh liver was added, results based on the height of the bubbles produced. It was hypothesised that the highest concentration would generate the highest average while the lowest concentration would result with the lowest average. The results are considerably controversial due to the unexpected lack of reaction with the 3% and the 5% concentrations that would have further supported the hypothesis as it was predicted that there would be a positive reaction rate gradient. However, the results did loosely support the hypothesis should the 1% and 7% concentrations be taken into account discretely as there was a significant increase in both average and a clear increase in reaction rate.


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Bibliography BBC, G. B. (2011). Enzymes. Retrieved from: http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/enzymes/enzymes1.shtml Biology Online. (2005, December 17). Questions about catalase. Retrieved from http://www.biology-online.org/biology-forum/about3820.html Daily Mail. (2011, November 1). Hope of a breakthrough cure for high blood pressure that could save millions of lives every year . Retrieved from http://www.dailymail.co.uk/health/article-2055969/Cure-high-blood-pressure-save-millions-lives-year.html Hill, E. (2003). What are metabolic enzymes?. Retrieved from http://www.wisegeek.com/what-are-metabolic-enzymes.htm Takano, J. (n.d.). Importance of enzymes. Retrieved from http://www.pyroenergen.com/articles/enzymes.htm Williams, J. (1927). The decomposition of hydrogen peroxide by liver catalase. The Journal of General Physiology, 310-337. Retrieved from www.sciencegeek.net/Biology/biopdfs/Lab_Catalase.pdf

enzyme liver catalase hydrogen peroxide

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