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How to improve reliability of biology experiment?

I have done an experiment on the rate of reaction with increasing enzyme concentration ! We have to come up with reasons inaccurate results may have been obtained and how to improve the reliability of the experiment? Any Ideas? We used a syringe to measure the liquids therefore I was thinking that a glass volumetric pipette could be used in order to measure the liquids much more accurately and to improve the reliability of the results but what else could I talk about, perhaps different reaction times etc??? Thanks :smile:

Reply 1

SmegSlayer

Can you explain a bit more about the experiment? How did you measure the reaction rate?

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Reply 2

emmalav

Original post by SmegSlayer

Can you explain a bit more about the experiment? How did you measure the reaction rate?

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Sorry , we used milk protein solution and protease enzyme solution , we mixed them and recorded the time taken for the solution to turn from colourless to cloudy (i.e. for the protease to digest the milk protein)

Reply 3

SmegSlayer

Well it's possible you could have had some enzymes in the solution that were already denatured.
Also if you're increasing your enzyme concentration reaction rate will only increase up to a point (saturation). It will also depend on on how concentrated your substrate solution is. If you have a weak solution and highly concentrated enzyme solution your reaction rate will still happen at the same rate as if you had a medium enzyme solution.
Also don't forget temperature, PH etc. Google the michaelis menten curve

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Reply 4

emmalav

Original post by SmegSlayer

Thank you very much , however I wrote in my plan that I would control (keep the same) the conc of the milk protein and the temperature of the room constant (basically by staying in the same room) . I could write for example that the temperature differed as the windows or doors were open during certain times in my experiment giving me unreliable results, could I?

Reply 5

SmegSlayer

Original post by emmalav

Not unless it got very cold. You would probably need a difference of about 10ºC to affect anything and even that probably wouldn't be measurable through observation.
If your substrate is the same concentration throughout then you need to think about enzyme concentration and saturation. Does the reaction change the pH of the solution and how sensitive is your enzyme to pH?
Also human error. Anything to do with colour change is subjective. You cannot be sure that each solution reached the same level of cloudiness without measuring the amount of light passing through the solution. If you were working with other people they may see differently to you

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(edited 11 years ago)

Reply 6

ash92:)

Original post by emmalav

Repeats (I feel) always need to be mentioned where reliability is concerned. Repeating several runs of the experiment, calculating an average, identifying outliers, etc.

Reply 7

User1014865

Original post by ash92:)

Repeats (I feel) always need to be mentioned where reliability is concerned. Repeating several runs of the experiment, calculating an average, identifying outliers, etc.

This, really.

Reply 8

crh898

we have done a similar experiment, and with regards to repeats, have said that the class results could be accumulated, providing a larger results pool to help identify anomalies and provide a more concise mean.