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Lab report - vessel size and bacterial growth

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I hate lab reports. I just can't figure out how they are supposed to be structured and how you find perfect explanations and solutions to the problems encountered. I hate lab reports. I know you can get 6 points on each of the three criteria. My best score is 4-3-2. That's crap, because I'm quite good at biology otherwise.

So, however, now we've just done this wonderful practical where we investigated the effect of vessel size on bacterial growth of E.Coli. Of course there's a report on this. Have anyone here done the same practical and feel like they can explain what happens? And does anyone know a site or something where you can find reports that have received great grades? Because I have no example to look at, just my own old, crappy ones - and that doesn't help. At all.

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Guest Lily Bean
Isn't this it? But you have to be VIP
[url="http://www.ibsurvival.com/forum/index.php?showtopic=100"]http://www.ibsurvival.com/forum/index.php?showtopic=100[/url]

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[quote name='Lily Bean' post='16598' date='May 14 2008, 05:00 PM']Isn't this it? But you have to be VIP
[url="http://www.ibsurvival.com/forum/index.php?showtopic=100"]http://www.ibsurvival.com/forum/index.php?showtopic=100[/url][/quote]

Yeah, of course it is! Ha, how clumsy, I did not notice. However, I'm not VIP so I guess I must try to figure it out myself. Thanks anyway!

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Maybe you could explain further on what the lab was about and the problem? I haven't done a lab like that but if you could describe, we could try to explain if we know it.

Regarding the lab criteras and structure - I don't have any advice there and it could be a bit hard to find a good example. When the syllabus changed, they also changed the assessment and critera of the lab reports. How this affects the structure is beyond me but as far as I know, if a person is a 2009 candidate, they should not put up their lab reports until they have finished the IB due to risk of plagirism.

The common 'structure' though with lab reports is basically --> intro, aim, hypothesis, variables, materials, procedure, results, analysis of results, discussion, evaluation.

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[quote name='Afterglow' post='16602' date='May 14 2008, 06:52 PM']Maybe you could explain further on what the lab was about and the problem? I haven't done a lab like that but if you could describe, we could try to explain if we know it.

Regarding the lab criteras and structure - I don't have any advice there and it could be a bit hard to find a good example. When the syllabus changed, they also changed the assessment and critera of the lab reports. How this affects the structure is beyond me but as far as I know, if a person is a 2009 candidate, they should not put up their lab reports until they have finished the IB due to risk of plagirism.

The common 'structure' though with lab reports is basically --> intro, aim, hypothesis, variables, materials, procedure, results, analysis of results, discussion, evaluation.[/quote]


Oh, yeah, I forgot that you 08'ers have another syllabus. However your common structure advice was great info :D Thanks.

Okey, so the practical dealt with bacterial growth and how different factors affect the bacterial growth of E.coli, being a facultative anaerobic bacteria. I did an experiment on how the size of the vessel affects the bacterial growth, and my results were not very 'accurate', I guess (but I don't KNOW) that the bigger the vessel, the faster the bacterial growth, due to more oxygen or something, but this was not the case in my particular practical (my results did not confirm this).

So, what I wonder is if anyone here knows what results are expected in this practical and what outside factors that might have affected my result, (I think, but then again don't KNOW, that one reason can be that when we tempered the solution the temperature was not held as a constant, because we had to use two different water baths.)

Okey, I know this might be hard to grasp if you haven't done the particular practical yourself, but maybe someone has a hum about it? :) Just tell me if I need to add any further information. Edited by QueenSara

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[quote name='QueenSara' post='16607' date='May 14 2008, 09:22 PM']Oh, yeah, I forgot that you 08'ers have another syllabus. However your common structure advice was great info :) Thanks.

Okey, so the practical dealt with bacterial growth and how different factors affect the bacterial growth of E.coli, being a facultative anaerobic bacteria. I did an experiment on how the size of the vessel affects the bacterial growth, and my results were not very 'accurate', I guess (but I don't KNOW) that the bigger the vessel, the faster the bacterial growth, due to more oxygen or something, but this was not the case in my particular practical (my results did not confirm this).

So, what I wonder is if anyone here knows what results are expected in this practical and what outside factors that might have affected my result, (I think, but then again don't KNOW, that one reason can be that when we tempered the solution the temperature was not held as a constant, because we had to use two different water baths.)

Okey, I know this might be hard to grasp if you haven't done the particular practical yourself, but maybe someone has a hum about it? :) Just tell me if I need to add any further information.[/quote]

Although it might be helpful if you had included some more detail, but I think I might have a grasp of the big picture. I don't know why you had included the fact that Oxygen concentration increases in the flask of ANAEROBIC bacteria? These bacteria do NOT use Oxygen, they ferment glucose/lactose or any other organic compound into ethanol and carbon dioxide. I don't think that Oxygen is a direct factor here.

Here are some things that you may take into consideration; have you kept the substrate concentration constant? (BTW what is the substrate you were using, i.e the bacterial 'food'?) The amount of bacteria? The temperature fluctuation you mentioned must be taken into consideration. Remember that bacteria favour dormant conditions with low temperature, thus a high temperature may kill the bacteria or reduce its activity. Also, how did you measure the bacterial growth? (Change in mass? Evolution of carbon dioxide gas?)

Finally, do NOT worry if your results come out completely different from what you had in mind. As some people say, "not having any result at all is a conclusion by itself." If you need any further assisstance, post back and try to make your methodology and questions more specific. (If you wish, pm me and I'll try and help :) ).

Hope this has helped. Have a nice day. :)

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[quote name='BIO-AQUA' post='17040' date='May 22 2008, 09:29 PM']Although it might be helpful if you had included some more detail, but I think I might have a grasp of the big picture. I don't know why you had included the fact that Oxygen concentration increases in the flask of ANAEROBIC bacteria? These bacteria do NOT use Oxygen, they ferment glucose/lactose or any other organic compound into ethanol and carbon dioxide. I don't think that Oxygen is a direct factor here.

Here are some things that you may take into consideration; have you kept the substrate concentration constant? (BTW what is the substrate you were using, i.e the bacterial 'food'?) The amount of bacteria? The temperature fluctuation you mentioned must be taken into consideration. Remember that bacteria favour dormant conditions with low temperature, thus a high temperature may kill the bacteria or reduce its activity. Also, how did you measure the bacterial growth? (Change in mass? Evolution of carbon dioxide gas?)

Finally, do NOT worry if your results come out completely different from what you had in mind. As some people say, "not having any result at all is a conclusion by itself." If you need any further assisstance, post back and try to make your methodology and questions more specific. (If you wish, pm me and I'll try and help :) ).

Hope this has helped. Have a nice day. :) [/quote]

Thanks, thanks, thanks! Exactly in time too; the lab report is due to tomorrow, I'm currently writing it :) Okey, I don't know about the oxygen, but our teacher said something about E.Coli not using oxygen in the first place, but that it could still affect (?) Okey, we used NB solution as the substrate, and, the amount of bacteria used was unfortunately not held constant.. The bacterial growth was measured through absorbance observation, we put test tubes with bacterial solution in a absorbance measuring machine.

Once again, thanks for the very detailed and informative answer, you really helped me out!

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[quote name='QueenSara' post='16597' date='May 15 2008, 12:40 AM']No one having a great example of a great lab report? :) I just need to see how a good lab report is structured.[/quote]


Hey there,

I was going through similar difficulties until i looked a some other people's reports just to get some ideas on how to structure them better.

Hope these are useful to you:

[url="http://startup.curtin.edu.au/study/writing/report.cfm"]http://startup.curtin.edu.au/study/writing/report.cfm[/url]

[url="http://www.writing.engr.psu.edu/workbooks/laboratory.html#results"]http://www.writing.engr.psu.edu/workbooks/...ry.html#results[/url]

[url="http://www.lboro.ac.uk/library/skills/Advice/Example%20report.pdf"]http://www.lboro.ac.uk/library/skills/Advi...le%20report.pdf[/url]


Should you need additional information, feel free to drop me a message.

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