How It Is Affected By Temperature. Essay, Research Paper
Harry Fox 11ST Biology
Science 1 – Strand 1: Planning Aim??????????? In my experiment, my aim is to find out any correlation
between rate of respiration? of glucose
by yeast and the mixture?s temperature. I shall do this by conducting an
experiment which will involve the timing of the yeast, water and glucose which
has been mixed with a little methylene blue. I shall time how long it takes to
revert to the original colour using a control. This shall be done at various
temperatures. To obtain the best range of values to use in my final experiment,
I shall conduct a preliminary experiment. This will also aid accuracy of the
final experiment by uncovering potential flaws in the method.Hypothesis
and Theory ??????????? There are many ideas to suggest that the change in
temperature will cause an increase of respiration in yeast. Yeast is a single
celled fungus made up mostly of protein which has been used for its
applications in fermentation. Yeast, after activation creates the ferments
carbon dioxide and ethyl alcohol by secreting the enzyme zymase (a complex of
12 enzymes) in the yeast which acts on simple sugars such as glucose. The
alcohol produced has been used in making wines and beers and the carbon dioxide
produced has been used in baking as it gets trapped in the dough and causes it
to rise. ??????????? Enzymes are catalysts which speed up reactions, they are
made from protein and are specific as to which substrate they work on. Enzymes
basically work due to the ?lock and key? theory, where the substrate substance
(the ?key?) ?fits? into the active site on the enzyme and they bind together,
the reaction takes place and the substrate unlocks to form one or more new
substances leaving the enzyme ready to perform the binding again. An enzyme can
only bind with a substrate that fits the shape of the active site unique to
that kind of enzyme. A zymase-complex enzyme will only bind with a glucose
molecule to produce the ferments carbon dioxide and alcohol which brings about
the fermentation in my experiment. This ties in with the Induced Fit theory
which states that the substrate cannot bring about catalysis and the reaction
itself, but the active site, when it comes in to contact with the substrate
slightly changes its shape to form an effective fit and arrangement of
catalytic groups on its surface which brings about the catalysis reaction. To
display this, think of a hand in a glove where the hand acts as the key and
substrate, inducing a change? in the
shape of the glove which acts as the enzyme. When some substrate substances
induce a fit with the enzyme, the enzyme may not be able to ?accept? some other
substrate(s). These ideas tie in with my experiment to explain the formation of
the products of respiration of yeast. ??????????? Yeast have to make energy, stored as ATP to carry out all
cellular functions. To do this they can respire both aerobically when there is
plenty of oxygen, but where oxygen is short, they respire anaerobically; by
this, they are called partial anaerobes. This produces less energy, but keeps
the yeast alive. Pyruvic acid has to be broken down in respiration when formed
by breaking down of glucose molecules, this can?t be done in the same way as it
is aerobically when respiring anaerobically which is how the carbon dioxide and
ethanol is formed through the zymase. Here is the equation for anaerobic
respiration:??????????? ????? enzymes in
cytoplasm ??????????????? ?????????
(zymase complex) glucose???? —————–>??? ethanol???? +??? carbon dioxide??? +energy C6H12O6???????? ?????
????????????????? 2C2H5OH?????? ????????
CO2??????????? 210
Kj/mole210Kj/mole in anaerobic
respiration as aposed to 2890Kj/mole in aerobic respiration There is 2ATP from each
respired glucose molecule – in aerobic there is 38ATP.??????????? 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. Faster particles will bring about more particle collisions and so the
reaction will take lace faster. Enzymes are sensitive to temperature changes up
until a certain temperature and will increase in their activity also. The
reactions that take place in the enzymes will be quicker and so will create
more of their products. As a general rule of thumb, it has been said that there
is a doubling of the rate of reaction for every 10?C rise this is called the
?Q10=2? theory. This should be evident when the concentration of the enzyme and
substrate are kept the same also. ??????????? Enzymes are sensitive to temperature up untill a certain
temperature where the shape of the active site is altered drastically, so much
so that binding hardly ever takes place. This is called denaturisation. Prediction ??????????? With reference to my theory, I predict that the rate and
speed of respiration of glucose by yeast will increase with temperature rise up
until a certain point where the enzyme used and secreted by the yeast will
become denatured and cease to function, reducing the rate significantly. This
is explained through Kinetic theory, yeast respiration and the nature of
enzymes. Initial
Investigation??????????? In my initial investigation, I simply counted the number
of bubbles released by the yeast in a 2 minute period. I did his because I only
wanted to uncover the general trend and temperatures where there was or wasn?t
notable activity so I could use this information when conducting my final
experiment. I used 1g of glucose and 1g of yeast, creating a 50:50 split, I
also used 10cm3 of distilled water. I mixed the three in a boiling
tube, warmed it a little and shook it to activate the yeast. I then left it for
one minute to let the mixture acclimatise to the temperature and then assembled
the apparatus as shown and counted how many bubbles were formed during 2
minutes. My independent variable was the temperature; the dependant being the
number of bubbles. I increased the temperature by 10?C each time. I took three
readings at each temp took their mean. I timed from the first bubble. Initial Investigation
Diagram
See Attatched Document Initial Investigation
Results
See Attatched Document
See Attatched Document
??????????? 0????????????????????????????????? 0????????????????????? 0????????????????????? 0????????????????????? 0
See Attatched Document
??????????? 10??????????????????????????????? 0????????????????????? 0????????????????????? 0????????????????????? 0?????????
See Attatched Document
??????????? 20??????????????????????????????? 4????????????????????? 6????????????????????? 4????????????????????? 4.7 ??????????? ??????????? 30??????????????????????????????? 11??????????????????? 9????????????????????? 10??????????????????? 10 ??????????? 40??????????????????????????????? 18??????????????????? 16??????????????????? 14??????????????????? 16 ??????????? 50??????????????????????????????? 22??????????????????? 20??????????????????? 19??????????????????? 20.3
See Attatched Document
??????????? 60??????????????????????????????? 4????????????????????? 10??????????????????? 6????????????????????? 5
See Attatched Document
At this last temperature, I
think the 10 bubbles at 60?C was an anomalous result. This may be due to
improper heating and will be discussed in my evaluation. It was not included in
my mean number of bubbles.
See Attatched Document
Graph Variables??????????? In my main experiment, I shall use the time taken for
methylene blue test tube with yeast and glucose solution to turn the colour of
the control as my dependant variable and the temperature as my independent
variable. ??????????? Here is a list of variables that can have an affect on my
experiment and also how I will control them if possible.Temperature Amount of methylene blue Amount of yeast Amount of glucose Volume of water Amount of shaking and
acclimatisation Light and atmospheric
conditionsTEMPERATURE??????????? Temperature of the experiment will have a great affect on
the results as explained by kinetic theory. Temperature will affect the rate of
yeast respiration. I shall keep the temperature of he mixture and water bath
under control by using a thermometer and checking it constantly. I shall also
keep swirling the thermometer to keep the heat distributed. Also, as it will
take longer for the temperature inside the test tube the same as the water
bath, I shall leave the apparatus for two minutes, keeping the temperature
constant.AMOUNT OF METHYLENE BLUE??????????? Methylene blue is sensitive to oxygen and will go blue
with contact with oxygen and colourless with the production of NADH during
glycolysis as the glucose is broken down. The amount of this would affect the
accuracy of the readings as the rate of NADH production affects the methylene
blue and a differing amount of methylene blue would not give fair and reliable
results. I shall keep the amount of drops of methylene blue the same at each
timing. AMOUNT OF YEAST??????????? The amount of yeast is crucial, more yeast means more
glucose will be respired and more products created. An imbalance will upset the
results. The amount of yeast will be weighed out on an accurate top-pan balance
each time.AMOUNT OF GLUCOSE??????????? The amount of glucose will affect the results also, as
more glucose means that there are potentially more products, which would make
the results accurate or the experiment fair. The glucose will be weighed out
each time using an accurate top-pan balance.VOL. OF WATER??????????? The volume of water may have a slight affect to the
results as it may cause less accuracy when distributing the heat in the test
tube. The volume of water will be kept constant by using a measuring cylinder
at each preparation.ACLIMATISATION AND SHAKING??????????? Acclimitisation and shaking will help to activate the
yeast and prepare the solution for timing. If it is improperly mixed,
acclimatised to temperature or activated, the results would not be fair and
inaccurate. I will shake the test tube thoroughly each time until I can see
bubbles being created well and I shall do this while it is warm to aid
activation. I shall also leave this in the water bath at the required heat for
two minutes, regulating the temperature with the Bunsen.LIGHT + ATMOSPHERIC
CONDITIONS??????????? These would not have a great deal of affect on my
experiment and are beyond my control. Some of the substances may be sensitive
to these, but I doubt they are sensitive enough to affect the results.?Diagram of final experimentApparatus Bunsen Burner Stopwatch Yeast Glucose Stand and Gauze Methylene-blue Syringe Pipette Boiling tubes (x2) Beaker Bungs Method??????????? In my final experiment, I shall use methylene blue in the
solution. I shall time how long it takes for methylene blue to go colourless in
the solution, constantly checking against a control which contains a little
methylene blue for continuity. To avoid unfair contact to Oxygen in the air, I
will? put a layer of oil over the
mixture. I shall weigh out 2g of glucose and 2g of yeast this time and 25cm3
of water to aid accuracy.? My
independent variable is the temperature and the dependant is the time taken to
change colour of control. ??????????? I shall take readings from 20?C to 60?C at 10?C
intervals. I will start from 20?C as I found out from my initial investigation
that there was no respiration activity below this temperature. I shall proceed
in this sequence as it is the easiest way of collecting results and will help
to find out other flaws at a lower temp.?
Also to aid accuracy, I shall take three readings at each interval and
take the mean.Results
headingsTime (s)????????????????????????????????? t1???????? t2???????? t3???????? T(mean)???? Rate (S-1)Temp (?C)????????????????????????????? Safety
See Attatched Document
HAZARD?????? ??????
DANGER(0-3)?? ? LIKELIHOOD(0-3)???? SCORE???? ACTION
See Attatched Document
Burn (Bunsen,??????????? 1????????????????????????????????? 2????????????????????????????????? 2????????? ?
Goggles, care hot water)?????? ?????
????????????????????????????????????????????????????????????????????????????????????????? ???when heating ?????????
See Attatched Document
Broken glass????????????? 2????????????????????????????????? 2
???????????????????????????????? 4????????? ?
Goggles, care ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ?? when hot and ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ?handling, clean ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? up
all fragments Broken ?????????????????????? 3????????????????????????????????? 1????????????????????????????????? 3????????? Care when using thermometer??? ????????????????????????????????????????????????????????????????????????????????????????????? don?t
hit hard, or ??????????????????????????????????????????????????????????????????????????????????????????????? ????????????? leave to roll off desk.Biology
Science 1 – Strand 2: Obtaining Revised
Method??????????? I have made only slight alterations to my proposed method
in the planning. I have kept everything the same, except that I shall take
multiple readings of smaller intervals around the ?plateau? of my results so as
to gain a more accurate understanding of what is happening and where the peak
in activity happens. This will also help me to analyse my hypothesis.Variables??????????? ??????????? ????? ??Time taken for solution to decolourise : Dependant Variable ??????????????????????? ???????? Temperature of solution : Independent
VariableRange: 20?C – 60?C in 10?C intervals mapping out plateau in 2?C
intervals from 42?C – 56?C. Measurements for both variables have been taken and
I have calculated the mean after taking three readings at each interval.ResultsSee Attatched Document Time(s)?????????? t1???????????????????? t2???????????????????? t3???????? ???
T(mean)?? Rate (S-1)???? x103
See Attatched Document
At 60?C the solution started to decolourise but with the last two, it
didn?t fully decolourise showing eventual denaturisation of the yeast?s
enzymes. Converting and manipulating data usually proves useful and aids
analysis and I have been able to calculate the rates for my results with my
dependant variable using 1/t. As this is inverse, and rates should
always be in seconds, the unit I shall use is?
S-1. I have made my rate results positive by multiplying them
by 103 so making it easier for me to plot and use.To aid the final analysis and to certify precise and reliable results,
I decided to map out the top plateau of results at 2?C intervals. The values
used cover the rise, peak and fall of the plateau. The results for this are
shown below. This will allow me to form an accurate optimum temperature for the
respiration of yeast.? had taken all the
precautions that I had done previously and used the same method. I will talk
about the validity of all my results in my Evaluating.See Attatched Document
Temp(?C)?? t1(s)???? t2??????
t3????? Time(mean)????? Rate (S-1)???????? x103??????
See Attatched Document
42??????? ?????? 125????? 109???? 116????????? 117???????????????? 0.00855????????? ?
8.55
See Attatched Document
44??????? ??????? 96?????? 107????? 105???????? 102???????????????? 0.00980????????? ?
9.80
See Attatched Document
46??????? ??????? 100????? 92?????? 95?????????? 96??????????????????? 0.0104??????????? ?
10.4See Attatched Document
??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ??????????????????????????????????????????????? I have ensured that my results are accurate by controlling all the
variables stated in my Planning. I also took care when using the equipment so
as to retain continuity throughout the experiment. For this, I checked
everything was set up correctly at each reading and prepared my solution in the
same way. I did not prepare a ?batch? of solutions as this would have given
some more time to acclimatise and more time to react and respire, changing the
conditions. When weighing out glucose and yeast on the top pan balance, I
checked that the air bubble was always centered and adjusted it accordingly, if
left uncentered, this could cause biased results. When measuring out distilled
water, I carefully checked that the bottom of the water?s meniscus sat
horizontal with the required gradient on the measuring cylinder when looked at
from 90? at the side. I also kept the same water in the water bath so as to
keep fair the distribution of heat to the test tubes, I mixed this as well.To further manipulate my results I shall record logs of my results so I
can plot this in my analysis. This will also display my results in such a way
that will allow me to easily find an optimum temperature for anaerobic
respiration in yeast. It will also allow me to calculate the Q10 mean value for
my experiment. This would go some way to see the accuracy of my results, but
mostly to see whether the reaction is in line with the Q10 theory and
regularity of the rate of reaction. I will plot log temp against log rate? to generate my log graph. This is one of
many data manipulation methods I shall use in my analysis to find out as much
as I can from my data. Here are my log tables including the results taken when
plotting out the plateau:See Attatched Document
??? 20?? 1.301?????????????? ???? 2.36???
?????? 0.373????????????? ??? 30?? 1.477?????????????? ???? 3.31???
?????? 0.198 ??? 40?? 1.602?????????????? ?? ??7.41??? ?????? 0.870 ??? 42?? 1.623?????????????? ???? 8.55???
?????? 0.932 ??? 44?? 1.643?????????????? ???? 9.80???
?????? 0.991 ??? 46?? 1.663?????????????? ???? 10.4???
?????? 1.017 ??? 48?? 1.681?????????????? ???? 11.2?????????? 1.049??? ??? 50?? 1.699?????????????? ???? 11.6?????????? 1.065? ??? 52?? 1.716?????????????? ???? 12.2?????????? 1.086 ??? 54?? 1.732?????????????? ???? 10.7?????????? 1.029 ??? 56?? 1.748?????????????? ???? 10.2?????????? 1.009
See Attatched DocumentBiology Science 1 – Strand
3: Analysis Summary????????? I found that as the
temperature increased, the rate of respiration increased with it. I also found
that the rate of respiration dropped of completely after a certain point,
highlighting the denaturisation of the yeast?s enzymes.
See Attatched Document
??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
????????? ???????????????????????????????????????????? ?????????????????????????????????????????????????? This shows that
the temperature
See Attatched Document
??????????????????????????????????????????????????????????????????????????????????????????????????????????????? a certain point
where respiration ??????????????????????????????????????? ??????????????????????????????????????????????? stops.??????????????????????????????????????????????????????????????? Temp
(?C)To calculate the Q10 gradient of my results so I can gain information
about the nature of the reaction, I shall create a graph of my logs given in my
Obtaining. From my log graph I can give the optimum temperature for yeast
respiration and calculate the Q10 reading for my experiment.I can calculate my Q10 value as shown: ? See Attatched Document See Attatched Document
See Attatched Document Conclusion ??????? I have found that as I
increased the temperature of the yeast solution, the rate of respiration of the
yeast increased to a certain point where, as the temperature rose to a certain
level, (in my case about 58?C) the rate of respiration eventually cut off. I
have also found that my Q10 value is 1.43. Seeing as the most accurate value
for a Q10 reaction is 2 (the rate of reaction doubling for every 10?C rise)
this makes my reaction look a bit inaccurate yet with positive signs of
correlation. A Q10 reading as low as 1.43 suggests there were either faults
with the method or apparatus or that the reaction was not a true Q10=2
reaction; this reaction should be a typical Q10=2 reaction, so my method or
apparatus? probably give the
inaccuracies. I will talk further about this in strand iv to suggest reasons. ??????????? My hypothesis and
prediction can be backed up with the findings; from looking at my results and
graphs you can see the rise and fall of respiration, further displayed by the
reaction?s Q10 reading which, although quite a lot less than 2, it still gives
the presence of the reaction?s ?sensitivity? (through zymase) to temperature.
Thus my hypothesis and prediction are shown to be present and displayed to a
large extent. They are explained due to the theories of enzyme-substrate with
lock and key and kinetics. Where these meet is when kinetic theory states that
an increase in temperature means more particle collisions between reactants and
so a faster rate of reaction; and in enzyme-substrate where the enzyme is
sensitive to heat, and about a certain temperature, the active site will begin
denaturing, so slowing and eventually stopping the reaction. This will give an
area where the rate of respiration drops off and goes to nothing instead of a
precise ?cut-off? point. These both apply to my experiment and were described
in my planning. ??????????? Biology Science 1 – Strand 4: Evaluation My Method??????????? The experiment went
quite well as I was able to obtain sets of recordings and calculate means,
rates and logs, and my Q10 value from them.I did not find any results to be anomalous when looking at the results
table. This could be explained by the small spread of results at each interval
and that the reaction could not be totally accurately controlled with the
apparatus used.I think that the method I used, whilst giving results, was also quite
sensitive to changes and didn?t allow to tap the full potential of the
experiment. I would suggest using equipment which would not allow any biased
results or ignore anything that is happening in the solution. I would want to
spread out the solution in something like a pert dish to give maximum surface
area to help conduct heat and to evenly spread the methyl blue. I would
consider either not using the methyl blue colour change technique at all or use
a substance which is more precise as I felt that the method did not allow
accurate use of methyl blue because of how it was used and what it acted on.
This added to the slight ?unpredictability? of the experiment.My Results ??????????? ??????????? To make sure that the
results were as reliable as I could make them, I calculated the mean of three
results at each interval when dealing with the rate and also used these to
produce my log values. ??????????? I took all precautions
to make the apparatus used to be reliable and give good values so I think the
slight unreliability was caused by the preparation of the solution and the ?unpredictability?
of how the reaction went that came with it. To obtain more reliable results I
would want complete continuity with preparations, maybe arranging ?sets? of
substances to create multiple solutions beforehand or preparing them but not
actually activating the yeast so as to prevent any getting a ?head start? over
the others. This would ensure that all the preparations are the same and would
give continuity. I would want to be more strict and thorough with preparing
solutions and mixing them up. I would want each one to be thoroughly
acclimatised to the surroundings and had the same amount of methyl blue and
same activating and mixing time. This would help give more reliable results
throughout. ??????????? If I were to further
investigate this experiment and my results, I would probably want to calculate
the point where the enzymes begin to denature for respiration in yeast. I could
also examine the change in rate between the intervals to determine validity and
continuity, also running them through maybe more intricate calculations
involving log. At this stage, I shouldn?t think there is to be much more I
could do. I wouldn?t want to investigate any other variables or reactions at
this time.